WO1991017995A1

WO1991017995A1 - New penem dithiocarbamates, their use and production methods

Info

Publication number: WO1991017995A1
Application number: PCT/IT1991/000041
Authority: WO
Inventors: Maria Altamura; Federico Arcamone; Danilo Giannotti; Vittorio Pestellini; Piero Sbraci
Original assignee: A Menarini Industrie Farmaceutiche Riunite SRL
Current assignee: A Menarini Industrie Farmaceutiche Riunite SRL
Priority date: 1990-05-16
Filing date: 1991-05-14
Publication date: 1991-11-28
Anticipated expiration: 1992-11-16
Also published as: IT1239275B; AU7853591A; IT9009393A0; PT97676A; IT9009393A1

Abstract

A compound of general formula (I), wherein R1 is a hydrogen atom, C1-C6 alkyl, C1-C6 alkoxy, cycloakyl or hydroxyalkyl, the alcoholic function of the hydroxyalkyl being free or protected; R2 is a free or esterified carboxy group or a carboxylate anion; R3 and R4 are each independently either hydrogen or C1-C6 alkyl, C1-C6 hydroxyalkyl or mercaptoalkyl, aminoalkyl or alkyl substituted with a quaternary ammonium group; cycloalkyl, arylalkyl or heterocyclyl-alkyl; a 5-6 membered, saturated or unsaturated heterocyclic ring, which can contain supplementary heteroatoms, such as oxygen, sulfur and nitrogen; an aryl group, or R3 and R4 form together a 3-7 membered, saturated or unsaturated heterocyclic ring, which can contain supplementary heteroatoms, such as oxygen, sulfur or nitrogen.

Description

NEW PENEM DITHIQCARBAMATES. THEIR USE AND PRODUCTION METHODS

Technical field

The invention relates to penem compounds of general formula

to processes for their preparation and to pharmaceutical and veterinary compositions containing such compounds as active principles, for use as antibiotics and antibacterial agents.

Background al

Penem derivatives are well known in the art as antibacterial agents.

UK-A-2 097 786 discloses for example the process for the production of

(5R)-2-carbamoyloxymethyl-6-(1 R-hydroxyethyl)-2-penem-3-carboxylic acid and salts thereof, as antibacterial agents.

It is well known in the art (Alpegiani et al., Heterocycles 23, 2255 (1985) and

Heterocycles 27, 49 (1988)) that 2-thiomethyl penem derivatives having a general formula (VII) in acqueous solution undergo equilibration to thiometylene penams isomers of formula (VIII).

(VI I) (VIII) The thiomethylene penam is the major product particularly in the case of the alkyl derivatives (i.e. with R=alkyl). This is a real problem because of the very low antibacterial activity of the penam isomers (VIII).

Known penem derivatives have poor chemical stability. This instability is one of the most frequent limitations to the pharmaceutical use of penem derivatives (vide R.B.Morin, M.Gorman "Chemistry and Biology of β-Lactam Antibiotics" Academic Press, 1982, vol.2, page 323).

Disclosure of the invention

Starting from this prior art, it is an object of the invention to provide new penem derivatives suitable as antibiotics and antibacterial agents as well as pharmaceutical and veterinary compositions containing said new penem derivatives.

It is a further object of the invention to provide penem derivatives which are chemically more stable than currently known penem derivatives.

It is a further object of the invention to provide new penem derivatives which can be prepared in a particularly favorable proportion between the penem and penam isomers.

It is a further object of the invention to provide a new process for the preparation of new penem derivatives.

Accordingly, the invention firstly refers to new penem derivatives of the general formula (I)

0) wherein:

- Ri is a hydrogen atom, lower alkyl, lower alkoxy, cycloalkyl or hydroxyalkyl , the alcoholic function of the hydroxyalkyl being free or protected. The substituent in the 6 position has the -configuration as well as the β-configuration.

- R2 is a free or esterified carboxy group or a carboxylate anion. When R2 is an esterified carboxy group it is a group COO- linked through the oxygen atom to a organic radical, such as a C1-C6 alkyl group, for example methyl or ethyl; a halo-substituted C-i-Cβ alkyl group, for example 2,2,2-trichloroethyl; a C2-C6 alkenyl group, for example allyl; an optionally substituted aryl group, for example phenyl and p-nitrophenyl; an optionally substituted aryl-C-|-C6 alkyl group, for example benzyl, p-nitrobenzyl and p-methoxybenzyl; or groups such as benzhydryl, o-nitrobenzhydryl, acetonyl, trimethylsilyl, t-butyldimethylsilyl and t-butyldiphenylsilyl. The definition of R₂ as an esterified carboxy group includes also a carboxy group esterified with any residue which is known to undergo metabolic activation in vivo and having favorable pharmacokinetic properties, including acetoxymethyl, pivaloyloxymethyl or any group of the general formula

-COO-CH(R₅)-OCOOR₆ or -COO-CH2-NHCOR7

wherein R5, Re, R7 are alkyl having from 1 to 6 carbon atoms or aryl.

- R₃ and R₄ are each independently either hydrogen or: a) a C1-C6 alkyl group, optionally substituted without limiting the present invention with halogen, CF₃, CN, CONRsRg, OR10, SRn, wherein Rs, R9, R .o, F.11 represent hydrogen atom, Ci-Cβ alkyl, aryl, arylalkyl b) an optionally substituted C-₁-C₆ hydroxyalkyl or mercaptoalkyl c) an optionally substituted aminoalkyl group or an alkyl group substituted with a quaternary ammonium group _{+ /} ^R12

-N - R.3

wherein R12, R13, R14 are each independently a hydrogen atom or an optionally substituted alkyl, arylalkyl or aryl radical d) an optionally substituted cycloalkyl, arylalkyl or heterocyclyl-alkyl group e) a heterocyclyl group, wherein the heterocycle has a 5-6 membered, saturated or unsaturated ring and can contain supplementary heteroatoms, such as oxygen, sulfur and nitrogen f) an aryl group.either unsubstituted or substituted with OH, OCH3, NH2, COOH, CONH2 or similar groups or g) R3 and R4 can together form an optionally substituted, 3-7 membered, saturated or unsaturated heterocyclic ring, which can contain supplementary heteroatoms, such as oxygen, sulfur or nitrogen, the nitrogen atom of the heterocyclic ring being optionally substituted with a Ci-Cβ alkyl , formyl, arylalkyl, aryl or heterocyclyl group or forming a quaternary ammonium salt.

The present invention includes all the possible geometrical and optical isomers of the compounds of formula (I) either in the form of isomeric mixture or in the form of the individual separated isomers.

Preferably, the compounds of formula (I) have a (5R.6S) configuration.

The preferred R1 group is a lower hydroxyalkyl such as an (α-hydroxy)ethyl radical.

The (α-hydroxy)ethyl radical has preferably the (1 R) configuration, i.e. a

R configuration at the α-carbon atom of the ethyl group. When the hydroxyalkyl group is protected, the protecting group is preferably p-nitrobenzyloxycarbonyl, allyloxycarbonyl, t- butyldimethylsilyl or trimethylsilyl.

When R2 is an esterified carboxy group, it is preferably allyl, although other known protecting groups such as p-nitrobenzyl can also be included, or it is an ester residue which is known to be hydrolized in vivo , such as acetoxy methyl, α-acetoxyethyl or pivaloyloxymethyl and equivalent groups. R3 and R4 are preferably hydrogen, optionally substituted C-i-Cβ alkyl, hydroxyalkyl, optionally substituted aryl, arylalkyl, such as benzyl, or heterocyclyl-alkyl, or are linked together in a saturated heterocyclic ring or in a heteroaromatic five or six atom ring system, also containing one or more additional heteroatoms, including N, O, S, such as for example 1 -pyrrolidyl, 4-morpholyl or 1-piperazinyl, wherein the nitrogen atom in the position 4 of the piperazine ring can be optionally substituted with a C-i-Cβ alkyl, aryl, arylalkyl or heterocyclyl group.

As already said also the pharmaceutically acceptable salts of the compounds of formula (I) wherein R2 is COOH are included within the scope of the invention. The said salts may be salts with inorganic bases such as for example alkali or alkaline- earth metal hydroxides, preferably sodium and potassium hydroxides, and salts with organic bases, including aminoacids such as for example lysine and like salts usually formed with penicillins and cephalosporins. The invention includes also internal salts, i.e. zwitterions.

Pharmaceutically acceptable compositions containing the compounds of formula (I), wherein R2 is preferably a carboxy group or a salt thereof or a metabolically activable ester group, in admixture with the usual carriers for oral and parenteral administration are also included in the present invention.

The compounds of the present invention possess a wide spectrum of antibacterial activity and also have β-lactamase inhibiting activity.

Compounds of formula (I) can be prepared from the corresponding hydroxymethyl compounds (II) (Scheme 1 ), wherein R1 is as defined above (usually α-hydroxyethyl) and Y is an ester residue, such as for example allyl or p-nitrobenzyl. Compounds of formula (II) are well known intermediates which can be prepared (Scheme 1 ) from the azetidinone compounds (III) or from the natural penicillin derivatives (IV) following published procedures (see for example W.J.Leanza et al., Tetrahedron, 15, 2505 (1983); E.Fontana et al., J.Lab.Comp.Radiopharm., 24, 41 (1986)).

The following scheme (already cited) illustrates the preparation of the compounds of formula (I) according to the invention. SCHEME 1

The penem alcohols (II) are activated as their sulfonyl derivatives (V), wherein R1 and Y are as defined above, and Z is an alkyl or aryl residue (usually methyl or p-tolyl), by reacting compounds (II) with the suitable sulfonyl chloride and an organic base, such as for example triethylamine or N.N-diisopropylamine, in an inert organic solvent, such as for example methylene dichloride or chloroform, at a temperature ranging from -70 to +20°C. The sulfonyl derivatives (V) are allowed to react with an inorganic (usually sodium or ammonium) salt of an optionally substituted carbamodithioic acid in an organic solvent such as for example methyl sulfoxide, dimethyl formamide, dioxane or tetrahydrofuran, usually at a temperature of -20°/+20°C; the reaction can be carried out on the crude or isolated sulfonyl derivatives (V). At the end of the reaction, the dithiocarbamoyl penems (VI) are recovered by conventional work-up. When Ri is hydroxyalkyl, the reaction sequence is carried out with the alcoholic function protected with the conventional protecting groups, such as p-nitrobenzyloxycarbonyl, allyloxycarbonyl, t- butyldimethylsilyl or trimethylsilyl. Alternatively, the reaction can be carried out on the free dialcohol derivative (II) (Rι-=CH3CHOH-). The protecting group is then removed at the end of the reaction sequence.

Compounds of formula (I) useful as antibacterial agents are finally obtained from the corresponding ester derivatives (VI), by hydrolysis or hydrogenolysis or by other known methods.

We have now found that the 2-dithiocarbamoyl penems (I) can be prepared in a particularly favorable proportion between the penem and penam isomers; the final products thus obtained are provided with a high level of antibacterial activity, compared with standard β-lactam antibiotics, particularly against gram positive strains, such as Sarcina lutea, Bacillus subtilis, Staphylococcus aureus.

Detailed description of preferred modes for carrying out the invention

The following examples are illustrative but should not be regarded as limiting the invention.

EXAMPLE 1

Ally! (5R.6S .-2-M -pyrrolidinethiocarbonylthiomethyl .-6-[(1 R .-1 -tert-butyldimethyl- silyloxy-ethyl]-penem-3-carboxvlate

4 g (10 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were dissolved in dry methylene dichioride (100 mL) and the solution cooled, under nitrogen, to 0°C. Triethylamine (2.1 mL, 15 mmol) and methanesulfonyl chloride (1.2 mL, 15 mmol) were added dropwise at the same temperature. At the end of the addition the mixture was stirred at 5°C for 30 min. The solution was then washed with cold water , 5% aqueous NaHCθ3 and water, dried over Na2S04 and evaporated to give a yellow solid. The crude product was dissolved in methyl sulfoxide (100 mL). 2 g (12.2 mmol) of ammonium 1 -pyrrolidinedithiocarbamate were added and the mixture stirred at room temperature for 2 h. The solution was poured into cold water and the white crystalline product collected by filtration, washed with water and dried under vacuum.

Yield: 4 g (76%). m.p. : 117-120°C

IR : 1767, 1700 cm-^"1 ¹ H-NMR (CDCI3) : δ (ppm) : 0.05 (6H,s,Si(CH₃)2); 0.85 (9H,s,C(CH₃)3); 1.15

(3H,d,£U3-CH); 1.9-2.1 (4H,m,β-CH2); 3.6-3.7 (3H; α-CH₂ and H-6); 3.9-4.0 (2H, t, α-CH₂); 4.15-4.25 (1 H,m,H-8); 4.65-4.75 (2H,m,COOCU2-CH=); 4.90 (2H, ABq,

CH2S-CS); 5.15-5.45 (2H,m,=CH2); 5.5 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH).

EXAMPLE 2

AIM (5R.6S)-2-(N .N-dimethylamino-thiocarbonvlthiomethvn-6-r(1 R)-1 -tert- butyldimethylsilyloxy-ethyl]-penem-3-carboxvlate

8 g (20 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1-tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were dissolved in dry methylene dichloride (200 mL) and the solution cooled, under nitrogen, to 0°C. N,N-diisopropylethyIamine (5.2 mL, 30 mmol) and methanesulfonyl chloride (2.4 mL, 30 mmol) were added dropwise at the same temperature. At the end of the addition the mixture was stirred at 5°C for 30 min. The solution was then washed with cold water , 5% aqueous NaHC03 and water, dried over Na2Sθ4 and evaporated to give a yellow solid. ^* The crude product was dissolved in methyl sulfoxide (200 mL). 5 g (28 mmol) of sodium dimethyldithiocarbamate dihydrate were added and the mixture stirred at room temperature for 1 h. The solution was poured into cold water and extracted twice with ethyl acetate. The organic extract was washed with water, dried over Na2S04 and evaporated under vacuum. The crude product was crystallized by adding cold petroleum ether. Yield: 8.8 g (85%). m.p. : 113-115°C IR : 1789, 1692 cm^"1

1 H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.84 (9H,s,C(CH₃)3); 1.17 (3H,d,£!±3-CH); 3.36 and 3.55 (2x3H;s;N(CH₃)₂); 3.66 (1 H,dd,H-6); 4.15-4.25 (1 H,m,H-8); 4.65-4.75 (2H,m,COOCJ_j2-CH=); 4.90 (2H, ABq, £H₂S-CS); 5.15-5.45 (2H,m,=CH2); 5.49 (1 H,d,H-5); 5.8-6.0 (1 H,m.=CH).

EXAMPLE 3

AIM (5R.6S)-2-(4-morpholinethiocarbonvlthiomethyl .-6-[M R .-1 -tert-butyldimethyl- silvloxv-ethvll-penem-3-carboxvlate

The title product was obtained as described in Example 2 by substituting sodium

4-morpholinedithiocarbamate for sodium dimethyldithiocarbamate.

Yield : 68%. White solid. m.p. 136-8°C

IR : 1785, 1691 cm^"1

1 H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)3); 1 -18

(3H,d,£Ji3-CH); 3.65 (1 H,dd,H-6); 3.7-3.8 and 3.9-4.3 (8H,morpholine-CH₂); 4.2

(1 H,m,H-8); 4.65-4.70 (2H,m,COOCU2-CH=); 4.8-5.15 (2H,ABq,CH₂S-CS); 5.15-5.45

(2H,m,=CH2); 5.50 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH).

EXAMPLE 4

Ailyl .5R.6S)-2-(aminothiocarbonylthiomethvn-6-[M R .-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxvlate

2 g (5 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyioxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ). The crude product was dissolved in methyl sulfoxide (50 mL). 0.72 g (6.5 mmol) of ammonium dithiocarbamate were added and the mixture stirred at room temperature for 30 min. The solution was poured into cold water and extracted with diethyl ether. The organic extract was washed with water, dried over Na2Sθ4 and evaporated under vacuum. The crude product was purified by column chromatography on silica gel (diethyl ether-petroleum ether 40:60 v/v) Yield: 1.10 g (46%). Yellow oil.

¹ H-NMR (CDCI₃) : δ (ppm) : 0.05 (6H,s,Si(CH₃)2); 0.85 (9H,s,C(CH₃)3); 1.18 (3H,d-£U3-CH); 3.68 (1 H.dd.H-6); 4.2 (1 H,m,H-8).4.65 (2H, ABq, CJ bS-CS); 4.65- 4.70 (2H,m,COOCJH2-CH=); 5.2-5.45 (2H,m,-=CH2); 5.55 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH); 7.2-7.4.(1 H,br,NH₂).

EXAMPLE 5

AIM (5R.6S)-2-(N-benzylamino-thiocarbonvlthiomethyl .-6-[(1 R)-1 -tert-butylriimfithyl- silvloxv-ethvl]-penem-3-carboxvlate

2 g (5 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ).

The crude product was dissolved in methyl sulfoxide (50 mL). 1.3 g (6.5 mmol) of sodium N-benzyldithiocarbamate were added and the mixture stirred at room temperature for 40 min. The solution was poured into cold water and extracted with ethyl acetate. The organic extract was washed with water, dried over Na2Sθ4 and evaporated under vacuum. The crude product was purified by column chromatography on silica gel (diethyl ether/n-hexane 20:80 v/v). Yield: 1.12 g (40%). Yellow oil.

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)3); 1.18 (3H,d,£Jd3-CH); 3.68 (1 H,dd,H-6); 4.2 (1 H,m,H-8); 4.65-4.70 (2H,m,COOCJH2-CH=); 4.85 (2H,£H₂Ph); 5.2-5.45 (2H,m,=CH₂); 5.55 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH); 7.2- 7.4.(5H,m,Ar-H).

EXAMPLE 6

AIM (5R.6S)-2-(N-methyl-N-benzylamino-thiocarbonylthiomethvn-6-[(1 R.-1 -tert- butyldimethylsilyloxy-ethyll-penem-3-carboxylate

The title product was obtained as described in Example 5 by substituting sodium

N-methyl-N-benzyldithiocarbamate for sodium N-benzyldithiocarbamate.

Yield: 77% after column chromatography on silica gel (ethyl ether/petroleum ether

30:70 v/v) and crystallization from cold petroleum ether.

White solid, m.p. 86-88°C

IR : 1776, 1698 cιτrl

¹ H-NMR (CDCI₃) : δ (ppm) : 0.05 (6H,s,Si(CH₃)₂); 0.85 (9H,s,C(CH₃)₃); 1.18

(3H,d,£J±3-CH) ;3.22 (3H,N-CH₃); 3.67 (1 H,dd,H-6); 4.20 (1 H,m,H-8); 4.67

(2H_Im,COOCU2-CH=); 4.95 (2H,ABq,CH₂S-CS); 5.15-5.45 (2H,m,=CH2); 5.51

(1 H,d,H-5); 5.8-6.0 (1 H,m,=CH); 7.15-7.4 (10H,m,Ar-H).

EXAMPLE 7

Allyl (5R.6S.-2-((4-methyl-piperazin-t -yl .-thiocarbonylthiomethyl .-6-[M R .-1 -tert- butyldimethylsilyloxy-ethyl]-penem-3-carboxylate

The crude product was dissolved in methyl sulfoxide (50 mL). 1 .2 g (6 mmol) of sodium N-(4-methyl-piperazin-1 -yl)-dithiocarbamate were added and the mixture stirred at room temperature for 1 h. The solution was poured into cold water and the separated product solified by treating with a saturated aqueous NaCI solution. The white crystalline product was collected, washed with water and dried under vacuum.

Yield: 2.2 g (79%). m.p. 157-9°C

IR (KBr): 1785, 1690 cm-¹

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)₃); 1.18

(3H,d.£Ji3-CH);2.3 (3H,s,N-CH₃); 2.47 (4H,t,N-CH of the piperazine ring); 3.65

(1 H,dd,H-6); 4.18 (1 H,m,H-8); 3.92 and 4.32 (2x2H,br,N-CH₂ of the piperazine ring);

4.67 (2H,m,COOC_H2-CH=); 4.90 (2H,ABq,QJl2S-CS); 5.15-5.42 (2H,m,=CH₂); 5.48

(1H,d,H-5); 5.8-6.0 (1 H,m,=CH).

EXAMPLE 8

AIM (5R.6S ■-2-(N.N-dibenzvlammo-thiocarbonylthiomethyl .-6-[M R .-1 -tert- butyldimethylsilyloxy-ethvl]-penem-3-carboxvlate

The title product was obtained as described in Example 5 by substituting sodium N,N- dibenzyldithiocarbamate for sodium N-benzyldithiocarbamate. Yield: 57% after column chromatography on silica gel. Yellow oil.

¹ H-NMR (CDCI₃) : δ (ppm) : 0.05 (6H,s,Si(CH₃)2); 0.85 (9H,s,C(CH₃)3); 1.22 (3H,d,£H3-CH); 3.68 (1 H,dd,H-6); 4.22 (1 H,m,H-8); 4.65-4.70 .2H.m.COOCH-_-CH=): 4.87 (4H.s.CHoPh : 5.0 (2H,ABq,CH₂S-CS); 5.15-5.45 (2H,m,=CH₂); 5.50 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH); 7.15-7.4 (10H,m,Ar-H). EXAMPLE 9

AIM (5 R.6S . -2-(N-phenylami no-thiocarbonylthiomethyl . -6-f M R . -1 -tert- butyldimethylsilyloxy-ethyll-penem-3-carboxylate

2 g (5 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see

Example 1 ).

The crude product was dissolved in dioxane (60 mL). 1.12 g (6 mmol) of ammonium

N-phenyldithiocarbamate were added and the mixture stirred at room temperature for

1 h. The solution was poured, under stirring, into cold water and treated with sodium chloride. The separated yellow solid was filtered under vacuum and dissolved again in ethyl ether. The ethereal solution was washed with water, dried over Na2S04 and evaporated.

The crude product was purified by column chromatography on silica gel

(cyclohexane/ethyl acetate 75:25 v/v)

Yield: 0.62 g (22%).

(3H ,d,CH₃-CH); 3.65 (1 H,dd,H-6); 4.2 (1 H,m,H-8); 4.6 (2H,m,COOC± -CH=) ;

5.15-5.40 (2H,m,=CH2); 5.51 (1 H,d,H-5); 5.75-5.95 (1 H,m,-=CH); 7.2-7.5.(5H,m,Ar-H).

EXAMPLE 10

Ally! (5R.6S .-2-(N-methyl-N-phenylamino-thiocarbonylthiomethvn-6-[M R .-1 -tert- butyldimethylsilyloxy-ethyl]-penem-3-carboxvlate

4 g (10 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ). The crude product was dissolved in methyl sulfoxide (80 mL). 2.5 g (12 mmol) of sodium N-methyl-N-phenyldithiocarbamate were added and the mixture stirred at room temperature for 90 min. The solution was poured into cold water and extracted with ethyl ether. The organic extract was washed with water, dried over Na2Sθ4 and evaporated under vacuum. The crude oily product was crystallized by treating with a mixture of ethyl ether and petroleum ether (20:80 v/v). Yield: 2.9 g (51%). m.p. : 107-110°C

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)3); 1.18 (3H,d,£J±3-CH); 3.64 (1 H,dd,H-6);3.75 (3H,s,N-CH₃); 4.18 (1 H,m,H-8); 4.6 (2H,m,COOCJ±2-CH=); 4.78 (2H,ABq.£Ji2S-CS); 5.15-5.40 (2H,m.=CH2); 5.46 (1 H,d,H-5); 5.75-5.95 (1 H,m,=CH); 7.2-7.3.(2H,m,Ar-H); 7.4-7.5 (3H,m,Ar-H)..

EXAMPLE 11

Allyl (5R.6S)-2-[N-methyl-N-(2-(2-pyridvnethyl)amino-thiocarbonylthiomethyl]-6-[(1 R -

1-tert-butvldimethvlsilvloxv-ethvl]-penem-3-carboxvlate

4 g (10 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1-tert-butyIdimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ).

The crude product was dissolved in methyl sulfoxide (80 mL). 2.8 g (12 mmol) of sodium N-methyl-N-(2-(2-pyridyl)ethyl)dithiocarbamate were added and the mixture ' stirred at room temperature for 90 min. The solution was poured into cold water and extracted with ethyl ether. The organic extract was washed with water, dried over Na2S04 and evaporated under vacuum. The crude product was purified by column chromatography on silica gel (hexane/ethyl ether 20:80 v/v) Yield: 5.2 g (73%). Yellow oil. IR(KBr): 1790, 1705 cm-¹ ¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)3); 1.2 (3H,m,OJl3-CH); 3.1-3.5 (5H,m,N-ChV_; and CH ); 3,66 (1 H.dd.H-6); 4.18 (1 H,m,H-8); 4.38 (2H,m,N-CH₂); 4.68 (2H,m,COC_JiiH2-CH=); 4.92 (2H,ABq,£t__2S-CS); 5.18-5.45 (2H,m,=CH₂); 5.49 (1 H,d,H-5); 5.82-6.03 (1 H,m,=CH); 7.08-7.22.(2H,m,Py-H); 7.60 (1 H,t,Py-H); 8.52 (1 H,d,Py-H).

EXAMPLE 12

Allyl(5R.6S)-2-[N-methyl-N-(2-pyridvhthiocarbonylthiomethyl1-6-f(1 R)-1-tert- butyldimethylsilyloxy-ethvl]-penem-3-carboxvlate

4 g (10 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ).

The crude product was dissolved in methyl sulfoxide (80 mL). 2.5 g (12 mmol) of sodium N-methyl-N-(2-pyridyl)dithiocarbamate were added and the mixture stirred at room temperature for 90 min. The solution was poured into cold water and extracted with ethyl acetate. The organic extract was washed with water, dried over Na2S04 and evaporated under vacuum. The crude product was purified by column chromatography on silica gel (hexane/ethyl ether 50:50 v/v). Yield: 2.4 g (42%). Yellow oil. IR(KBr): 1790, 1650 cm^"1

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)₃); 1 .18 (3H, m,£H.3-CH); ; 3.65 (1 H,dd,H-6); 3.77 (3H,d,N-CH₃) 4.20 (1 H,m,H-8); 4.63 (2H , m,C00C_H2-CH=); 4.85 (2H,ABq,£H_2S-CS); 5.15-5.4 (2H,m,=CH2); 5.48 (1 H,d,H-5); 5.78-6 (1 H,m,=CH); 7.28-7.40.(2H,m,Py-H); 7.77-7.88 (1 H,mPy-H); 8.58 (1 H,d,Py-H). EXAMPLE 13

AIM .5R.6S.-2-r(4(te-t-butoxvcarbonvl .Diperazin-1 -vl.-thiocarbonvlthiornethvl]-6-[M R .-

1-tert-butyldimethvlsilvloxv-ethvl1-penem-3-carboxvlate

The crude product was dissolved in methyl sulfoxide (50 mL). 1.7 g (6 mmol) of sodium N-(4(tert-butoxycarbonyl)piperazin-1-yl)-dithiocarbamate were added and the mixture stirred at room temperature for 2 h. The solution was poured into cold water and extracted with ethyl ether. The organic extract was washed with water, dried over Na2S04 and evaporated under vacuum. The crude oily product was crystallized by treating with petroleum ether. Yield: 2.5 g (77%). Yellow oil. m.p. 126-128°C IR (KBr)): 1767, 1698 cm"¹

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)₂); 0.87 (9H,s,C(CH₃)₃); 1.2 (3H,d,CU3-CH); 1.48 (9H,s,COO-C(CH₃)₃); 3.55 (4H,t,N-CH₂ of the piperazine ring); 3.68 (1 H,dd,H-6); 3.85-4.45 (4H,br,N-CH₂ of the piperazine ring; 1 H,m,H-8); 4.7 (2H, m,COOCJ±2-CH=); 4.95 (2H,ABq,£H2S-CS); 5.2-5.98 (2H,m,=CH₂); 5.2 (1 H,d,H-5); 5.82-6.05 (1 H,m,=CH).

^•EXAMPLE 14

AIM (5R.6S -2-[N-methyl-N-⁽2-N'.N'-dimethylaminoethvn-thiocarbonylthiomethyl]-6-

[(1 R)-1 -tert-butyldimethylsilyloxy-ethyl]-penem-3-carboxylate

2 g (5 mmol) of allyl (5R,6S)-2-hydroxymethyl-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (se Example 1 ).

The crude product was dissolved in methyl sulfoxide (50 mL). 1.2 g (6 mmol) sodium N-methyl-N-(2-N',N'-dimethylaminoethyl)dithiocarbamate were added and th mixture stirred at room temperature for 2 h. The solution was poured into cold wate and extracted with ethyl acetate. The organic extract was washed with water, drie over Na2Sθ4 and evaporated under vacuum. The crude product was purified b column chromatography on silica gel (ethyl acetate). Yield: 0.6 g (21 %). Yellow oil.

¹ H-NMR (CDCI₃) : δ (ppm) : 0.07 (6H,s,Si(CH₃)₂); 0.88 (9H,s,C(CH₃)3); 1.2 (3H,d,£H3-CH); ; 2.29 (6H,s,N-CH₃); 2.63 (2H,m,N-CH₂); 3.35- 3.56 (3H,m,N-CH₃) 3.7 (1 H.dd.H-6); 3.8-4.3 (3H,m,N-CH₂ and H-8); 4.7 (2H,m,COOCϋ₂-CH-=); 4.9 (2H,ABq,£H₂S-CS); 5.2-5.48 (2H,m,-=CH₂); 5.02 (1 H,d,H-5); 5.85-6.05 (1 H,m,=CH).

EXAMPLE 15

AIM f5R.6S.-2-(N.N-bis-(2-hydroxyethyl)amino-thiocarbonylthiomethyl.-6-fn R)-1 -tert butyldimethylsilyloxy-ethyl]-penem-3-carboxylate

The title product was obtained as described in Example 5 by substituting sodium N,N-bis-(2-hydroxyethyl)dithiocarbamate for sodium N-benzyldithiocarbamate. Yield: 55% after column chromatography on silica gel (ethyl acetate/n-hexane 50:50 v/v) and crystallization from cold petroleum ether. White solid, m.p. 115-117°C

¹ H-NMR (CDCI₃) : δ (ppm) : 0.02 (6H,s,Si(CH₃)2); 0.82 (9H,s,C(CH₃)₃); 1.19 (3H,d,£Ud₃-CH); 3.66 (1 H,dd,H-6); 3.9-4.2 (br.OH); 3.8-4.4 (br m,CH₂ of 2-hydroxyethyl group); 4.65 (2H,m,COOC±l2-CH-=); 4.87 (2H,ABq,CH₂S-CS); 5.15-5.45 (2H,m,=CH₂); 5.49 (1 H,d.H-5); 5.8-6.0 (1 H,m,=CH). EXAMPLE 16

Allyl (5R.6S)-2-(N.N-biR- 2-acetvloxv-ethvnamino-thiocarbonylthiomethvn-fi-rπ R.-1 - tert-butyldimethylsilyloxv-ethvll-Denem-3-carboxvlate

A solution of allyl (5R,6S)-2-(N,N-bis-(2-hydroxyethyl)amino-thiocarbonylthiomethyl)- 6-[(1 R)-1-tert-butyldimethylsilyloxy-ethyl]-penem-3-carboxylate (Example 15) (1.84 g, 3.28 mmol) in methylene dichloride (100 mL) was cooled to -10°C. Pyridine (0.92 mL, 11.4 mmol) and acetyl chloride (0.8 mL, 11.3 mmol) were added in sequence under nitrogen atmosphere. After stirring for 30 min at the same temperature, the solution was washed with water, dried over Na2S04 and evaporated.

Yield: 1.64 g (77%) after column chromatography on silica gel (ethyl ether/petroleum ether 70:30 v/v).

¹ H-NMR (CDCI₃) : δ (ppm) : 0.03 (6H,s,Si(CH₃)2); 0.85 (9H,s,C(CH₃)₃); 1.21 (3H,d,£J±3-CH); 2.08 (6H,s,OCOCH₃); 3.69 (1 H,dd,H-6); 4.0-4.5 (9H,br m,CH₂ of 2-acetyloxyethyl group and H-8); 4.70 (2H,m,COOC_H_2-CH-=) ; 4.91 (2H,ABq,CH₂S-CS); 5.20-5.45 (2H,m,=CH₂); 5.53 (1 H,d,H-5); 5.85-6.1 (1 H,m,=CH).

EXAMPLE 17

AIM (5R.6S -2-(N-methyl-N-benzyloxy)amino-thiocarbonylthiomethvh-6-[(1 R)-1 -tert- butyldimethylsilyloxy-ethyl]-penem-3-carboxylate

2 g (5 mmol) of allyl (5R,6S)-2-hydroxymethyI-6-[(1 R)-1 -tert-butyldimethylsilyloxy- ethyl]-penem-3-carboxylate were allowed to react with triethylamine and methanesulfonyl chloride in dry methylene dichloride as described above (see Example 1 ).

The crude product was dissolved in methyl sulfoxide (50 mL). 1.8 g (7.5 mmol) of sodium N-methyl-N-benzyloxydithiocarbamate were added and the mixture stirred at room temperature for 2 h. The solution was poured into cold water, extracted with ethyl acetate, dried over Na2S04 and evaporated. Yield: 2.32 g (89%).

¹ H-NMR (CDCI₃) : δ (ppm) : 0.01 (6H,s,Si(CH₃)2); 0.88 (9H,s,C(CH₃)₃); 1.2 (SH.d.SJ±s-CH); 3.67 (1 H,dd,H-6); 3.72 (3H,N-CH₃); 4.22 (1 H.rn.H-8); 4.7 (2H,m,COOCU2-CH=); 4.83 (2H,ABq,CH₂S-CS); 5.02 (2H,s,£H2P ); 5.20-5.4 (2H,m,=CH2); 5.52 (1 H,d,H-5); 5.85-6.05 (1 H,m,=CH); 7.35-7.55 (5H,m,Ar-H).

EXAMPLE S

AIM .5R.6S -2-(4-morpholinethiocarbonvlthiomethvl .-6-[(1 R .-1 -hvdroxvethvlj-penem

3-ςa Qxylate

To a stirred solution of allyl (5R,6S)-2-(4-morpholinethiocarbonylthiomethyl)-6-[(1 R)-1 - tert-butyldimethylsilyloxyethyl]-penem-3-carboxylate (7.2 g ; 13.2 mmol) in tetrahydrofuran (200 mL) were added in sequence acetic acid (4.5 mL; 78.7 mmol) and tetrabutylammonium fluoride trihydrate (12.5 g; 39.6 mmol).

After stirring at room temperature for 24 h, the mixture was diluted with ethyl ether, washed with water and 5% aqueous NaHC0₃, dried over Na2Sθ4 and evaporated.

The crude residue was purified by column chromatography on sislca gel (ethyl acetate/n-hexane 50:50 v/v), giving a white solid, m.p. 112-4°C

Yield : 4.3 g (76%).

No penam isomer was detected by NMR spectroscopy.

¹ H-NMR (CDCI₃) : δ (ppm) : 1.28 (3H,d,£H3-CH); 2.05 (1 H.br.OH); 3.65 (1 H,dd,H-6);

3.7-3.8 and 3.8-4.4 (8H,morpholine-CH₂); 4.55-4.75 (2H,m,COOC_H₂-CH-=); 4.9

(2H,ABq,£H₂S-CS); 5.15-5.45 (2H,m,=CH2); 5.52 (1 H,d,H-5); 5.856.05 (1 H,m,=CH).

IR :3435, 1778, 1701 cm^"1 EXAMPLE 19

AIM (5R.6S .-2-f N.N-dimethylaminothiocarbonylthiomethyl .-6-fM R .-1 -hvdroxyethyl]- penem-3-carboxvlate

To a stirred solution of allyl (5R,6S)-2-(N,N-dimethylaminothiocarbonylthiomethyl)-6-

[(1 R)-1 -tert-butyldimethylsilyloxyethyI]-penem-3-carboxylate (4 g; 8 mmol) in tetrahydrofuran (80 mL) were added in sequence acetic acid (2.75 mL; 48 mmol) and tetrabutylammonium fluoride (1 M solution in tetrahydrofuran: 24 mL, 24 mmol).

After stirring at room temperature for 24 h, the mixture was diluted with ethyl acetate, washed with water and 5% aqueous NaHC0₃, dried over Na2S04 and evaporated.

The crude residue was purified by column chromatography on silica gel (ethyl ether/n- hexane 80:20 v/v), giving a yellow oil.

Yield : 2.2 g (71 %).

¹ H-NMR (CDCI₃) : δ (ppm) : 1.22 (SH.d.^hb-CH); 2.5 (1 H,br,OH); 3.32 and 3.51

( 3 H e ach , s , N (C H ₃ )₂ ); 3.68 (1 H,dd,H-6) ; 4.18 (1 H,m, H-8); 4.6-4.8

(2H,m,COOC±L2-CH=); 4.83 (2H,ABq,£fcL2S-CS); 5.15-5.45 (2H,m,=CH2); 5.52

(1 H,d,H-5); 5.80-6.05 (1 H,m,=CH).

The presence of the 2-methyienepenam isomer (25%) could be detected in the

¹H-NMR spectrum (δ=7.1 ppm).

EXAMPLE 20

Allyl (5R.6S .-2-(4-pyrrolidinethiocarbonylthiomethvn-6-[M RV-1 -hvdroxyethylj-penem-

3-carboxvlate

The title product was obtained as previously described for the morpholine derivative

(see Example 18).

Yield : 90% after column chromatography on silica gel (ethyl ether/petroleum ether

80:20 v/v).

IR : 3470, 1786 cm^"1 ¹ H-NMR (CDCI₃) : δ (ppm) : 1.22 (3H,d,£tl3-CH);i .85-2.15 (4H,br,β-CH₂ of the pyrrolidine ring); 2.8 (1 H.br.OH); 3.62 and 3.88 (3H each,m,N-CH2); 4.15 (1 H,m,H-8) 4.55-4.75 (2H,m,COOCU2-CH=); 4.82 (2H.ABq,£t_2S-CS); 5.15-5.40 (2H,m,=CH2) 5.50 (1 H,d,H-5); 5.806.0 (1 H,m,=CH); 7.15 (s, =CH of the 2-methylene penam isomer 30%).

EXAMPLE 21

AIM (5R.6S)-2-(N-methyl-N-benzylamino-thiocarbonylthiomethvh-6-[M R .-1 - hydroxyethyl]-penem-3-carboxylate

The title product was obtained as previously described for the N.N-dimethylamino derivative (see Example 19).

Yield: 86% after comlumn chromatography on silica gel (ethyl acetate/cyclohexane

50:50 v/v).

¹ H-NMR (CDCI3) : δ (ppm) : 1.30 (3H,d,£HL3-CH); 2.05 (1 H.br.OH); 3.22 and 3.45

(3H,N-CH₃); 3.72 (1 H,dd,H-6); 4.22 (1 H,m,H-8); 4.68 (2H,m,COOC_H₂-CH=); 4.92

(2H,ABq,CH₂S-CS); 5.15-5.45 (2H,m,=CH₂); 5.52 (1 H,d,H-5); 5.8-6.05 (1 H,m,=CH);

7.1 -7.4 (10H,m,Ar-H).

The presence of the 2-methylenepenam isomer (10%) could be detected by the presence in the ¹³C-NMR spectrum of the methylenic =CH signal (δ=115 ppm).

EXAMPLE 22

AIM (5R.6S)-2-((4-methyl-piperazin-1 -yl .-thiocarbonylthiomethvn-6-[M R)-l - hvdroxyethyl]-penem-3-carboxylate

The title product was obtained as previously described for the N.N-dimethylamino derivative (see Example 19). ¹ H-NMR (CDCI3) : δ (ppm) :1.29 (3H,d,C±i3-CH);2.28 (3H,s,N-CH₃); 4.18 (1 H,m,H-8); 3.90 and 4.30 (2x2H,br,N-CH₂ of the piperidine ring); 4.7 (2H,m,COOCU2-CH=); 4.88 (2H,ABq,£t_2S-CS); 5.2-5.45 (2H.m,=CH2); 5.52 (1 H,d,H-5); 5.8-6.05 (1 H,m,=CH). The presence of the 2-methylenepenam isomer (30%) could be detected in the ¹ H- NMR spectrum (δ=7.1 ppm).

EXAMPLE 23

AIM (5R.6S.-2-(N.N-dibenzvlamino-thiocarbonvlthiomethvl )-6-[M R .-1 -hvdroxyethyl]- penem-3-carboxvlate

Yield : 65% after column chromatography on silica gel (ethyl acetate/n-hexane 50:50 v/v). H-NMR (CDCI3) : δ (ppm) : 1.28 (3H,d,£tL3-CH); 1.95 (i H.br.OH); 3.7 (1 H,dd,H-6);

4.22 (1 H,m,H-8); 4.55-4.8 (2H,m,COOCJ±2-CH=);4.85 (4H, s, £J±2Ph); 4.95

(2H,ABq,£H2S-CS); 5.20-5.45 (2H,m,-=CH₂); 5.55 (1 H,d,H-5); 5.856.05 (1 H,m,=CH);

7.1-7.4 (10H,m, Ar-H). The presence of the 2-methylenepenam isomer (30%) could be detected by the H-3 signal (δ=5.4 ppm in the ¹H-NMR spectrum) .

EXAMPLE 24

AIM (5R.6S .-2-(N-methyl-N-phenylamino-thiocarbonylthiomethyl ,-6-f. 1 R .-1 - hvdroxyethyl]-penem-3-carboxylate

The title product was obtained as previously described for the N.N-dimethyiamino derivative (see Example 19).

Yield : 75% after column chromatography on silica gel (ethyl ether/n-hexane 70:30 v/v). IR : 3450, 1785, 1703 cm^"1 H-NMR (CDCI₃) : δ (ppm) : 1.28 {3 ,ό,Q 3-CH); 2.0 (1 H.br.OH); 3.68 (1 H,dd,H-6); 3.72 (3H,s,N-CH₃); 4.18 (1 H.rn.H-8); 4.6-4.7 (2H,m,COOCJ±2-CH=); 4.75 (2H,ABq,£M2S-CS); 5.15-5.45 (2H,m,=CH2); 5.45 (1 H,d,H-5); 5.756.0 (1 H,m,=CH); 7.15-7.25 (2H, m, Ar-H); 7.35-7.5 (3H,m,Ar-H); 7.05 (s, =CH of the 2-methylene penam isomer : 20%).

EXAMPLE 25

Allyl (5R.6S .-2-[N-methyl-N-(2-f2-pvridvl .ethvlamino-thiocarbonylthiomethyl]-6-[M R)-

1 -hvdroxyethyl]-penem-3-carboxvlate

Yield : 65% after column chromatography on silica gel (ethyl ether/ethyl acetate

50:50 v/v).

IR : 3390, 1790, 1705 cm"¹ ¹ H-NMR (CDCI3) : δ (ppm) : 1.3 (3H,m.£tl3-CH); 1.83 (1 H.br.OH); 3.1 -3.45(5H,m,N-

CH₃ and CH₂); 3.7 (1 H,dd,H-6); 4.02-4.42 (3H,m,N-CH₃ and H-8); 4.58-4.77

(2H,m,COOCJ±2-CH=); 4.88 (2H,ABq,£ii2S-CS); 5.19-5.45 (2H,m,=CH₂); 5.51

(1 H,d,H-5); 5.82-6.04 (1 H,m,=CH); 7.08-7.26 (2H, m, Py-H); 7.6 (1 H,t,Py-H); 8.52

(1 H,d,Py-H). The presence of the 2-methylenepenam isomer (30%) could be detected by the H-5 signal (δ=5.48 ppm in the ¹H-NMR spectrum).

EXAMPLE 26

AllyU5R.6S)-2-[N-methyl-N-(2-pyridyl)thiocarbonylthiomathyll-6-fM R⁾-1 -hvdroxyethyl]- penem-3-carboxylate

Yield : 45% after column chromatography on silica gel (ethyl ether). H-NMR (CDCI₃) : δ (ppm) : 1.3 (SH.m.Gbb-CH); 1.82 (1 H.br.OH); 3.69 (1 H.dd.H-6); 3.77 (3H,d,N-CH₃); 4.20 (1 H.rn.H-8); 4.6-4.7 (2H,m,COOCJ±2-CH=); 4.82 (2H,ABq,£il2S-CS); 5.2-5.4 (2H,m,=CH₂); 5.5 (1 H,d,H-5); 5.79-6.02 (1 H,m,=CH); 7.28-7.40 (2H,m,Py-H); 7.77-7.88 (1 H.rn.Py-H); 8.58 (1 H,d,Py-H);7.06 (s, =CH of the 2-methylene penam isomer : 30%).

EXAMPLE 27

Allyl (5R.6S)-2-[(4-ftert-butoxycarbonvl .piperazln-1 -vlVthiocaι^*bonvlthiomβthyl]6-[(1 R)-

1-hvdroxyethyl]-penem-3-carboxvlate

Yield : 90% after column chromatography on silica gel (ethyl ether/n-hexane

80:20 v/v).

¹ H-NMR (CDCI3) : δ (ppm) : 1.32 (SH.d.GHs-CH); 1.48 (9H,s,COO-C(CH₃)₃); 3.55

(4H,t,N-CH₂ of the piperazine ring); 3.73 (1H,dd,H-6); 3.85-4.4 (4H,br,N-CH₂ of the piperazine ring; 1 H,m,H-8); 4.7 (2H,m,COOC±L2-CH=); 4.93 (2H,ABq,£H2S-CS); 5.23-

5.48 (2H,m,=CH₂); 5.5 (1 H,d,H-5); 5.83-6.07 (1 H,m,=CH); 7.12 (s =CH of the

2-methylene penam isomer : 30%).

EXAMPLE 28

AIM (5R.6S)-2-[(piperazin-1 -vl)-thiocarbonvlthiomethvl]-6-[ 1 R .-1 -hvdroxyethyl]- penem-3-carboxylate

Trifluoroacetic acid (4 mL) was added to a stirred solution of allyl (5R,6S)-2-[(4-(tert- butoxycarbonyl)piperazin-1 -yl)-thiocarbonylthiomethyl]-6-[(1 R)-1 -hydroxyethyl]- penem3-carboxylate (1.1 g; 2.08 mmol) in dichloromethane (20 mL). After stirring at room temperature for 10 min, the mixture was treated with NaHC0₃ (10 g), diluted with water and extracted with chloroform. The organic extract was washed with water, dried over MgSθ4 and evaporated under vacuum. The crude residue was purified b column chromatography on silica gel (chloroform/methanol 90:10 v/v).

Yield: 0.27 g (30%)

¹H-NMR (CDCI₃) : δ (ppm) : 1.33 (3H,d,CU3-CH); 1.8 (2H,br,OH and NH); 2.9

(4H,t,N-CH₂ of the piperazine ring); 3.73 (1 H,dd,H-6); 3.85-4.45 (4H,br,N-CH₂ of th piperazine ring; 1 H,m,H-8); 4.73 (2H,m,COOC±i2-CH=-); 4.95 (2H,ABq,£JH₂S-CS) 5.23-5.48 (2H,m,=CH2); 5.56 (1 H,d,H-5); 5.85-6.15 (1 H,m,=CH); 7.18 (s. =CH of the 2-methylene penam isomer : 20%).

EXAMPLE 29

Allyl (5R.6S.-2-(N.N-bis-(2-hvdroxyethyl ,amino-thiocarbonylthiomethyl .-6-[(1 R.-t - hydroxyethyl]-penem-3-carboxylate

Yield :95%.

The crude product was used in the following step without any further purification.

¹H-NMR (CDCI₃) : δ (ppm) : 1.26 (SH.d.QHs-CH); 3.68 (1 H,dd,H-6); 3.8-4.3 (br m,CH₂ of 2-hydroxyethyl group, H-8 and OH); 4.65 (2H,m,COOCJ±2-CH=); 4.82

(2H,ABq,CH₂S-CS); 5.2-5.4 (2H,m,=CH₂); 5.50 (1 H,d,H-5); 5.8-6.0 (1 H,m,=CH).

The presence of the 2-methylenepenam isomer (30%) could be detected in the

¹H-NMR spectrum (δ=7.02 ppm).

EXAMPLE 30

AIM (5R.6S)-2-(N.N-bis-(2-acetyloxyethvnamino-thiocarbonylthiomethyl)-6-[n RV1 - hydroxyethyl]-penem-3-carboxylate

Yield: 77% after column chromatography (ethyl acetate/n-hexane 50:50 v/v). ¹H-NMR (CDCI3) : δ (ppm) : 1.26 (3H,d,£hb-CH); 2.1 (6H,s,OCOCH₃); 3.72 (1 H.dd.H-

6); 4.0-4.5 (br m,CH₂ of 2-acetyloxyethyl group and H-8); 4.7 (2H,m,COOC±i2-CH=);

4.87 (2H,ABq,CH₂S-CS); 5.2-5.4 (2H,m,=CH2); 5.55 (I H.d.H-5); 5.85-6.05

(1H,m,=CH).

The presence of the 2-methylenepenam isomer (25%) could be detected in the

¹H-NMR spectrum (δ=7.01 ppm).

EXAMPLE 31

AIM (5R.6S)-2-(N-methvl-N-benzvloxv.amino-thiocarbonvtthiomethyl )-6-[M R .-1 - hvdroxvethvl]-penem-3-carboxvlate

Yield: 70% after column chromatography (ethyl acetate/n-hexane 50:50 v/v).

¹H-NMR (CDCI3) : δ (ppm) : 1.26 (3 ,d,___z_3-C ); 2.6 (1 H.br.OH); 3.68 (3H,N-CH₃);

3.70 (1 H,dd,H-6); 4.22 (1 H,m,H-8); 4.70 (2H,m,COOC±i2-CH=); 4.78 (2H,ABq, CH₂S-

CS); 5.0 (2H,s,£_H Ph); 5.20-5.45 (2H,m,=CH₂); 5.55 (1 H,d,H-5); 5.85-6.05

(1 H,m,=CH); 7.35-7.50 (5H,m,Ar-H).

The presence of the 2-methylenepenam isomer (35%) could be detected in the

¹H-NMR spectrum (δ=7.07 ppm).

EXAMPLE 32

Sodium (5R.6S .-2- . N.N-dimethylamino-thiocarbonylthiomethyl .-6-[M R .-1 - hvdroxyethyl]-penem-3-carboxylate

To a solution of allyl (5R,6S)-2-(N,N-dimethyiamino-thiocarbonylthiomethyl)-6-[(1 R)-1- hydroxyethyl]-penem-3-carboxylate (2.7 g; 7 mmol) in dry ethyl acetate (80 mL) were added in sequence, under nitrogen, sodium 2-ethyl hexanoate (2.3 g in 20 mL of ethyl acetate; 1 4 mmol), triphenylphosphine (100 mg ; 0.38 mmol) and tetrakis(triphenylphosphine)palladium(0) (400 mg; 0.35 mmol). The resulting mixture was stirred at room temperature for 30 min. Ethyl ether was added under stirring: the precipitate product was collected under nitrogen, washed with ether and dried under vacuum to give a mixture of the penem and 2-methylenepenam isomers (3:1 from ¹H-NMR spectrum; 60% overall yield). The mixture was separated by reverse phase column chromatography on Lichroprep RP18 (water/acetonitrile 97:3 v/v).

Sodium (5R,6S)-2-(N,N-dimethylamino-thiocarbonylthiomethyl)-6-[(1 R)- 1 -hydroxyethyl]-penem-3-carboxylate

White powder

¹ H-NMR (D₂0) : δ (ppm) : 1.20 (3H,d,J=6.5Hz,£J±₃-CH); 3.33 and 3.45

(2x3H,s,N(CH₃)2); 3.77 (1 H,dd,H-6); 4.14 (1 H,m,H-8); 4.73 (2H,ABq,£t_2S-CS); 5.47

(1 H,d,J=1.5Hz,H-5).

MS (FAB) : 371 (M+Na)+; 393 (M + 2Na)⁺.

Sodium (5R,6S)-2-(N,N-dimethylamino-thiocarbonylthiomethylene)-6-

[(1 R)-1 -hydroxyethyl]-penam-3-carboxylate

White powder

¹ H-NMR (D₂0) : δ (ppm) : 1 .23 (3H,d,J=6.5Hz,CJ±3-CH); 3.35 and 3.43

(2x3H,s,N(CH₃)₂); 3.47 (1 H,dd,H-6); 4.21 (1 H,m,H-8); 5.33-35 (2H, H-5 and H-3); 6.69

(1 H,d,J=1.4Hz,=£HS).

EXAMPLE 33

Sodium (5R.6S -2-(4-mnrpholinethiocarbonvlthiomethvl .-6-[(1 R .-1 -hvdroxvethvl]- penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-(4-morpholine- thiocarbonylthiomethyl)-6-[(1 R)-1 -hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see Example 32).

Yield: 57%, as a mixture of the penem and 2-methylenepenam isomers (4:1 from ¹H-

NMR spectrum)

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 97:3 v/v).

Sodium (5R-6S)-2-(4-morpholinethiocarbonylthiomethyl)-6-[(1 R)-1 - hydroxyethyl]-penem-3-carboxylate

White powder.

¹ H-NMR (D₂0) : δ (ppm) : 1.20 (3H,d,C±i3-CH); 3.7-4.4 (10H : morpholine-CH_2, H-6 and H-8); 4.8 (2H,ABq,£h_2S-CS); 5.48 (1 H,d,H-5);.

MS (FAB) : 413 (M+Na)+; 435 (M+2Na)+.

Sodium (5R,6S)-2-(4-morpholinethiocarbonylthiomethylene)-6-[(1 R)-1 - hydroxyethyl]-penam-3-carboxylate

White powder.

¹ H-NMR (D₂0) : δ (ppm) : 1.22 (SH.d.C± -CH); 3.35 (1 H.H-6) 3.7-4.4 (9H : morpholine-CH₂ and H-8); 5.30-35 (2H, H-5 and H-3);.6.74 (1 H,d,J=1.4Hz,=£LiS).

EXAMPLE 34

Sodium (5R.6S)-2-(pyrrolidinethiocarbonvlthiomethvn-6-[(1 R.-1 -hvdroxyethyl]-penem-

3-ga ^χyiatβ

To a solution of allyl (5R,6S)-2-(pyrrolidinethiocarbonylthiomethyl)-6-[(1 R)-1- hydroxyethyl]-penem-3-carboxylate (3.2 g; 7.7 mmol) in dry tetrahydrofuran (80 mL) were added in sequence, under nitrogen, triphenylphosphine (100 mg; 0.38 mmol), tetrakis(triphenylphosphine)palladium(0) (460 mg; 0.4 mmol) and a solution of sodium 2-ethyl hexanoate (1.9 g; 11.4 mmol) in THF/CH₂CI 1 :1 (30 mL). The resulting mixture was stirred at room temperature for 1 h.

Ethyl ether was added under stirring: the precipitate collected under nitrogen, washed with ether and dried under vacuum to give a mixture of the penem and

2-methylenepenam isomers (3:1 from ¹H-NMR spectrum; 45% overall yield).

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetone 95:5 v/v).

Sodium (5R, 6S)-2-(pyrr olid inethio car bony Ithio met hyl)-6-[(1 R)-1 - hydroxyethyl]-penem-3-carboxylate

White powder

¹H-NMR (D 0) : δ (ppm) : 1.20 (3H,d,J=6.5Hz,£]H₃-CH); 1.85-2.05 (4H,m,β-CH₂ of the pyrrolidine ring); 3.55-3.65 (2H,m,α-CH2 of the pyrrolidine ring); 3.7-3.85 (3H,m, -CH2 of the pyrrolidine ring and H-6); 4.14 (1 H,m,H-8); 4.79 (2H,ABq,£Ji₂S-CS); 5.48

(1 H.H-5).

UV: λ(nm): 255, 315.

Sodium (5R,6S)-2-(pyrrolidinethiocarbonylthiomethylene)-6-[(1 )-1 - hydroxyethyl]-penam-3-carboxylate

White powder

¹H-NMR (D₂0) : δ (ppm) : 1.23 {3 ,ό,.--6.5 z,Q__3-C ); 1.85-2.05 (4H,m,β-CH2 of the pyrrolidine ring); 3.47 (1 H,dd,H-6); 3.6-3.7 and 3.7-3.8 (2x2H,m,α-CH₂ of the pyrrolidine ring); 4.21 (1 H,m,H-8); 5.31 (1 H,d,H-3); 5.35 (1 H,d,H-5); 6.68 (1 H,d,=£HS). UV: λ (nm) : 275 EXAMPLE 35

Sodium (5R.6S.-2-(N-methvl-N-benzvlamino-thiocarbonylthiomethyl.-6-[M R.-1 - hvdroxyethvl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-(N-methyl-N-benzylamino- thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see Example 32).

Yield: 40%, as a mixture of the penem and 2-methylenepenam isomers (3:1 from

¹H-NMR spectrum)

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 90:10 v/v).

Sodium (5R-6S)-2-((N-methyl-N-benzyiamino)-thiocarbonylthiomethyl)-6-

[(1R)-1-hydroxyethyl]-penem-3-carboxylate

White powder.

¹H-NMR (D₂0) : δ (ppm) : 1.19 (3H,d,CH₃-CH);3.27, 3.41 (3H, N-CH₃), 3.71

(1H,m,H-6) ;4.13 (1H,m,H-8); 5.44 (1H,d,H-5);.7.15-7.4 (5H,m,Ar-H).

UV:λ(nm):315.

Sodium (5R,6S)-2-((N-methyl-N-benzylamino)-thiocarbonyl- thiomethylene)-6-[(1R)-1-hydroxyethyl]-penam-3-carboxylate

¹H-NMR (D₂0) : δ (ppm) : 1.21 (3H,d,CH₃-CH);3.3 and 3.42 (3H, N-CH₃)_;4.2 (1H,m,H-8); 5.32 (1H,d,H-5);6.72 (1H,d,=£HS);.7.15-7.4 (5H,m,Ar-H). UV:λ(nm):280.

EXAMPLE 36

Sodium ,5R.6S)-2-((4-methvl-piperazin-1-yl)-thiocarbonylthiomethyl)-6-[MR.-1- hvdroxyethyl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-((4-methyl-piperazin-1-yl)- thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see Example 32).

Yield: 42%, as a mixture of the penem and 2-methylenepenam isomers (2:1 from

¹H-NMR spectrum).

The mixture was separated by reverse phase column chromatography on

Lichroprep RP18 (water/acetonitrile 97:3 v/v).

Sodium (5R,6S)-2-((4-methyl-piperazin-1-yl)-thiocarbonylthiomethyl)-6-

[(1 R)-1 -hydroxyethyl]-penem-3-carboxylate

White powder.

¹H-NMR (D₂0) : δ (ppm) : 1.19 (SH.d.QHs-CH); 2.24 (3H,s,N-CH₃)_;2.55 (4H,m,N-CH₂ of the piperazine ring); 3.78 (1H,dd,H-6); 3.8-4.3 (4H,br,N-CH2 of the piperazine ring);

4.14 (1H,m,H-8); 4.8 (2H,ABq,£h_2S); 5.48 (1H,d,H-5).

UV:λ(nm):310.

Sodium (5R,6S)-2-((4-methyl-piperazin-1-yl)-thiocarbonyl- thiomethylene)6-[(1R)-1-hydroxyethyl]-penam-3-carboxylate

¹H-NMR (D₂0) : δ (ppm) : 1.21 (3H,d,CH₃-CH); 2.24 (3H,s,N-CH₃)_;2.55 (4H,m,N-CH₂ of the piperazine ring); 3.49 (1H,dd,H-6); 3.8-4.3 (4H,br,N-CH2 of the piperazine ring);4.2 (1 H,m,H-8); 5.30 (1 H.H-3); 5.32 (1 H.H-5); 6.72 (1 H,=C±IS). ^•UV: λ(nm): 258. EXAMPLE 37

Sodium (5R.6S .-2-(N-methyl-N-phenylamino-thiocarbonylthiomethyl .-6-fM R .-1 - hvdroxyethyl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-(N-methyl-N-phenylamino- thiocarbonylthiomethyI)-6-[(1R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see

Example 32).

Yield: 52%, as a mixture of the penem and 2-methylenepenam isomers (4:1 from

¹H-NMR spectrum).

The mixture was separated by reverse phase column chromatography on

Lichroprep RP18 (water/acetonitrile 95:5 v/v).

Sodium (5R-6S)-2-(N-methyl-N-phenylamino-thiocarbonylthiomethyl)-6-

[(1 R)-1 -hydroxyethyl]-penem-3-carboxylate

White powder.

¹H-NMR (D₂0) : δ (ppm) : 1.19 (3H,d,CU3-CH); 3.65-3.75 (4H overall, N-CH3 and

H-6);4.14 (1H,m,H-8); 5.40 (1H,d,H-5); 7.2-7.5 (5H,m,Ar-H).

Sodium (5R,6S)-2-(N-methyl-N-phenylamino-thiocarbonyl- thiomethylene)-6-[(1 R)-1 -hydroxyethyl]-penam-3-carboxylate

White powder.

¹H-NMR (D₂0) : δ (ppm) : 1.21(3H,d, i±3-CH); 3.4 (1H,dd,H-6); 3.7 (3H.S.N-CH3); 4.14

(1H,m,H-8); 5.28 (1H,m,H-5 and 1H,m,H-3); 6.68 (1H,d,=CHS); 7.2-7.5 (5H,m,Ar-H)

^' EXAMPLE 38 (5R.6S.-2-((4-methyl-piperazin-1 -yl .-thiocarbonylthiomethyl .-6-[M R .-1 -hvdroxyethyl]- penem-3-carboxylic acid

To a solution of allyl (5R,6S)-2-((4-methyl-piperazin-1-yl)-thiocarbonylthiomethyl)-6- [(1R)-1-hydroxyethyl]-penem-3-carboxylate (0.28 g; 0.5 mmol) in dry ethyl acetate (10 mL) were added in sequence, under nitrogen, 2-ethyl hexanoic acid (0.11 g; 0.75 mmol), triphenylphosphine (30 mg; 0.1 1 mmol) and tetrakis(triphenylphosphine) palladium(O) (100 mg; 0.086 mmol).

The resulting mixture was stirred at room temperature for 60 min.

Ethyl ether was added under stirring: the precipitate product was collected under nitrogen, washed with ether and dried under vacuum to give a mixture of the penem and 2-methylenepenam isomers (3:1 from ¹H-NMR spectrum; 60% overall yield).

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 90:10 v/v).

(5R,6S)-2-((4-methyl-piperazin-1-yl)-thiocarbonylthiomethyl)-6-[(1 R)-1 - hydroxyethyl]-penem-3-carboxylic acid

White powder. H-NMR (CDCI₃) : δ (ppm) : 1.19 (3H,d,£]±3-CH); 2.82 (3H,s,N-CH₃)_; 3.25-3.60

(4H,m,N-CH2 of the piperazine ring); 3.74 (1 H,dd,H-6); 3.95-4.25 (4H,br,N-CH₂ of the piperazine ring; 1 H,m,H-8); 4.75 (2H,ABq,£h_2S); 5.48 (1 H,d,H-5).

UV: λ(nm): 310.

(5R,6S)-2-((4-methyl-piperazin-1-yl)-thiocarbonylthiomethylene)-6-[(1 R)- 1-hydroxyethyl]-penam-3-carboxylic acid

White powder.

¹ H-NMR (CDCI3) : δ (ppm) : 1.21 (3H,d,£]i3-CH); 2.82 (3H,s,N-CH₃)_; 3.25-3.60

(4H,m,N-CH₂ of the piperazine ring); 3.12 (1 H,dd,H-6); 3.95-4.25 (4H,br,N-CH₂ of the piperazine ring; 1 H,m,H-8); 5.30 (1 H.H-3); 5.32(1 H.H-5); 6.7(1 H,=CHS).

UV: λ(nm):258 EXAMPLE 39

.5R.6S.-2-((4.4-dimethyl-piperaziπ-1 -vl .-thiocarbonylthiomethyl.-6-rM R)-1 - hydroxyethvl]-penem-3-carboxvlate

Methyl iodide (1 mL) was added to a solution of (5R,6S)-2-((4-methyl-piperazin-1-yl)- thiocarbonylthiomethyl)-6-[(1 R)-1 -hydroxyethyl]-penem-3-carboxylic acid (100 mg;

0.25 mmol) in tetrahydrofuran (15 mL) and the resulting mixture allowed to react overnight without stirring.

The precipitate product was collected under nitrogen, washed with ether and dried under vacuum to give a mixture of the penem and 2-methylenepenam isomers (4:1 from ¹H-NMR spectrum; 40% overall yield).

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 90:10 v/v).

(5R,6S)-2-((4,4-dimethyl-piperazin-1-yl)-thiocarbonylthiomethyl)-6-[(1 R)- 1 -hydroxyethyl]-penem-3-carboxylate

White powder.

¹ H-NMR (D₂0) : δ (ppm) : 1.21 (SH.d. J±s-CH); 3.23 (6H,s,N-CH₃)_; 3.52-3.64 (4H,m,N-CH of the piperazine ring); 3.78 (1 H,dd,H-6); 4.15 (1 H,m,H-8); 4.38-4.55 (4H,br,N-CH₂ of the piperazine ring); 4.78 (2H,ABq,£H2S); 5.5 (1 H,d,H-5). UV: λ(nm): 310.

(5R,6S)-2-((4,4-dimethyl-piperazin-1 -yl)-thiocarbonylthiomethylene)-6- [(1 R)-1 -hydroxyethyl]-penam-3-carboxylate ^' White powder.

¹ H-NMR (D₂0) : δ (ppm) : 1.25 (SH.d.Cϋs-CH); 3.24 (6H,s,N-CH₃)_; 3.57-3.64 (4H,m,N-CH₂ of the piperazine ring); 3.49 (1 H,dd,H-6); 4.23 (1 H,m,H-8); 4.38-4.52 (4H,br,N-CH₂ of the piperazine ring; 1 H,m,H-8); 5.36 (1 H.H-3); 5.38(1 H.H-5); 6.68(1 H,=CHS). UV: λ(nm):275 EXAMPLE 40

Sodium .5R.6S)-2-[N-methyl-N-(2-(2-pvridvn-ethvlamino-thiocarbonvlthiomethvl]-6-

[(1 R)-1 -hvdroxyethyl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-[N-methyl-N-(2-(2-pyridyl)- ethylamino-thiocarbonylthiomethyl]-6-[(1R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see

Example 32).

Yield: 48%, as a mixture of the penem and 2-methylenepenam isomers (4:1 from ¹H-

NMR spectrum)

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitriie 97:3 v/v).

Sodium (5R-6S)-2-[N-methyl-N-(2-(2-pyridyl)-ethylamino- thiocarbonylthiomethyl]-6-[(1 R)-1 -hydroxyethyl]-penem-3-carboxylate

White powder.

¹H-NMR (D₂0) : δ (ppm) : 1.2 (3H,d,CJJ3-CH); 3.03-3.38 (5H,m,N-CH₃ and CH₂); 3.72

(1H,dd,H-6); 4.03-4.88 (5H,m, N-CH₂, H-8 and CH₂S-CS); 5.42 (^"•:-' d,H-5); 7.17-7.3

(2H,m,Py-H); 7.68 (1 H,m,Py-H); 8 (1 H,d,Py-H).

U λ(nm):310.

EXAMPLE 41

Sodium (5R.6S)-2-rN-methyl-N-(2-pyridvhthiocarbonylthiomethvπ-β-rn R .-1 - hydroxyethyl]-penem-3-carboxylate

The title product was obtained starting from allyl (5R,6S)-2-[N-methyl-N-

(2-pyridyl)thiocarbonylthiomethyl]-6-[(1R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see

Example 32).

Yield: 30% as a mixture of the penem and 2-methylenepenam isomers (4:1 from ¹H-

NMR spectrum) The mixture was separated by reverse phase column chromatography on Lichroprep RP18 (water/acetonitrile 95:5 v/v).

Sodium (5R-6S)-2-[N-methyl-N-(2-pyridyl)thiocarbonylthiomethyl]-6- [(1 R)-1 -hydroxyethyl]-penem-3-carboxylate

White powder.

¹ H-NMR (D₂0) : δ (ppm) : 1.23 (SH.d.QHs-CH); 3.69 (3H,s,N-CH₃ ); 3.78 (1 H,dd,H-6);

4.17 (1 H,s, H-8 ); 4.7 (2H,ABq,CH₂S-CS); 5.49 (1 H,d,H-5); 7.49 (2H,m,Py-H); 8.0 (1 H, t, Py-H); 8.48 (1 H,d,Py-H).

UV: λ(nm): 315.

EXAMPLE 42

.5R.6S.-2-[(piperazin-1 -yl .-thiocarbonylthiomethylj-6-fH R -1 -hydroxyethyl]-penem-3- carboxylic acid

The title product was obtained starting from allyl (5R,6S)-2-[(piperazin-1 -yl)- thiocarbonylthiomethyl]-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the (5R,6S)-2-((4-methyl-piperazin-1 -yl)- thiocarbonylthiomethyl)-6-[(1 R)-1 -hydroxyethyl]-penem-3-carboxylic acid (see

Example 38).

Yield:21 %, as a mixture of the penem and 2-methylenepenam isomers (3:1 from

¹H-NMR spectrum).

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 90:10 v/v).

(5R,6S)-2-[(piperazin-1 -yl)-thiocarbonylthiomethyI]-6-[(1 R)-1 - hydroxyethyl]-penem-3-carboxylic acid

White powder.

¹ H-NMR (DMSO) : δ (ppm) : 1.16 (SH.d.CJis-CH); 2.85-3 (4H,br,N-CH₂ of the piperazine ring); 3.68 (1 H,dd,H-6); 3.85-4.35(4H,br,N-CH2 of the piperazine ring; 1 H,m,H-8); 4.82 (2H.ABq.GH2S); 5.5 (1 H,d,H-5). UV: λ(nm):310.

(5R-6S)-2-[(piperazin-1-yl)-thiocarbonylthiomethyl]-6-[(1 R)-1- hydroxyethyl]-penam-3-carboxylic acid

White powder.

¹ H-NMR (DMSO) : δ (ppm) : 1.08 (SH.d.C±b-CH); 2.85-3 (4H,br,N-CH2 of the piperazine ring); 3.05 (1 H,dd,H-6); 3.85-4.35(4H,br,N-CH2 of the piperazine ring;

1 H.m,H-8); 5.28(1 H.H-3); 5.35(1 H.H-5); 6.87 (1H,=CHS).

UV: λ(nm): 275.

EXAMPLE 43

Sodium (5R.6S)-2-(N.N-bis-(2-hvdroxyethvnamino-thiocarbonylthiomethvn-6-[M R.-1 - hvdroxvethyl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-(N,N-bis-(2-hydroxy- ethyl)amino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate following the procedure described above for the N.N-dimethylamino derivative (see

Example 32).

Yield: 42%, as a mixture of the penem and 2-methylenepenam isomers (3:1 from ¹H-

NMR spectrum).

The mixture was separated by reverse phase column chromatography on Lichroprep

RP18 (water/acetonitrile 97:3 v/v).

Sodi um (5R,6S)-2-(N_JN-bis-(2-hydroxyethyl)amino-thiocarbonyl- thiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate

White powder

¹ H-NMR (D₂0) : δ (ppm) : 1.20 (SH.d.Ghb-CH); 3.76 (1 H,dd,H-6); 3.8-4.2 (m, CH2 of the 2-hydroxyethyl group and H-8); 4.85 (2H,ABq,CH₂S-CS); 5.50 (1 H,d,H-5).

Sodium (5R-6S)-2-(N-N-bis-(2-hydroxyethyl)amino-thiocarbonyl- thiomethylene)-6-[(1 R)-1-hydroxyethyl]-penam-3-carboxylate

White powder ¹ H-NMR (D₂0) : δ (ppm) : 1.23 (SH.d.C±b-CH); 3.47 (1 H.dd.H-6); 3.8-4.25 (m, CH2 of the 2-hydroxyethyl group and H-8); 5.3-5.33 (2H, H-3 and H-5); 6.7 (1 H,s,=CH).

EXAMPLE 44

Sodium (5R.6S)-2-(N.N-bis-(2-acetvloxvethvπamino-thiocarbonylthiomethvn-6-[(1 R)- 1 -hvdroxyethyl]-penem-3-carboxvlate

The title product was obtained starting from allyl (5R,6S)-2-(N,N-bis-(2-acetyloxyethyl)- amino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate as described above for the N.N-dimethylamino derivative (see Example 32). At the end of the reaction, the reaction product was recovered by extraction with water; the acqueous solution was lyophylized and the mixture separated by reverse phase column chromatography on Lichroprep RP18 (water/acetonitrile 90:10 v/v) Yield: 48% as a mixture of the penem and 2-methylenepenam isomers (3:1 from ¹H-NMR spectrum).

Sodium (5R , 6S)-2-(N,N-bis-(2-acetyloxyethyl)a min o-thiocar bony I- thiomethyl)-6-[(1 R)-1 -hydroxyethyl]-penem-3-carboxylate White powder H-NMR (D₂0) : δ (ppm) : 1.21 (3H,d,C±L3-CH); 2.03 (6H,s,OCOCH₃); 3.77 (1 H,dd, H-6); 4.1 -4.2 and 4.3-4.5 (m, CH2 of the 2-acetyloxyethyl group and H-8); 4.77 (2H,ABq,CH₂S-CS); 5.49 (1 H,d,H-5).

Sodium (5R,6S)-2-(N,N-bis-(2-acetyloxyethyl)amino-thiocarbonylthio- methylene)-6-[(1 R)-1 -hydroxyethyl]-penam-3-carboxylate 'White powder

¹H-NMR (D₂0) : δ (ppm) : 1.25 (SH.d.C±is-CH^.Oδ (6H,s,OCOCH₃); 3.35 (1 H,dd,H-6); 4.1-4.5 (m, CH2 of the 2-hydroxyethyl group and H-8); 5.3-5.35 (2H, H-3 and H-5); 6.68 (1 H,s,=CH). EXAMPLE 45

Sodium (5R.6S.-2-(N-methyl-N-benzv[oxy amino-thiocarbonylthiomethyl -6-|Y1 R)-1 - hvdroxyethyl]-penem-3-carboxylate

The title product was obtained starting from allyl (5R,6S)-2-(N-methyl-N-benzyloxy)- amino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate.as described above for the N.N-dimethylamino derivative (see Example 32).

At the end of the reaction, the reaction product was recovered by extraction with water; the acqueous solution was lyophylized and the mixture separated by reverse phase column chromatography on Lichroprep RP18 (water/acetonitrile 90:10 v/v)

Yield: 51% as a mixture of the penem and 2-methylenepenam isomers (4:1 from

¹H-NMR spectrum).

Sodium (5 R,6S)-2-(N-methyl-N-benzyloxy)amino-thiocarbonylthio- methyl)-6-[(1 R)-1-hydroxyethyl]-penem-3-carboxylate

¹ H-NMR (D₂0) : δ (ppm) : 1.22 (SH.d.Gfcb-CH); 3.68 (3H,N-CH₃); 3.77 (1 H,dd,H-6);

4.15 (1 H,m,H-8); 4.58 (2H,ABq, CH₂S-CS); 5.05 (2H,s,Gt_2Ph); 5.48 (1 H,d,H-5); 7.35-

7.60 (5H,m,Ar-H).

Sodi um (5R,6S)-2-(N-methyl-N-benzyloxy)amino-thiocarbonylth io- methylene)-6-[(1 R)-1-hydroxyethyl]-penam-3-carboxylate H-NMR (D₂0) : δ (ppm) : 1.25 (3H,d,£H3-CH); 3.47 (1 H,dd,H-6); 3.70 (3H,N-CH₃);

4.20 (1 H.rn.H-8); 5.08 ⁽2H.s.CH9Ph. : 5.33 and 5.36 (2H,2s,H-5 and H-3); 6.62

(1 H,s,=CH); 7.35-7.60 (5H,m,Ar-H).

Claims

1. A compound of the following formula (I)

(I)

wherein:

- Ri is a hydrogen atom, Ci-Cβ alkyl, C-i-Cβ alkoxy, cycloalkyl or hydroxyalkyl , the alcoholic function of the hydroxyalkyl being free or protected.

- R₂ is a free or esterified carboxy group or a carboxylate anion.

- R₃ and R₄ are each independently either hydrogen or: a) an optionally substituted C-i-Cβ alkyl group b) an optionally substituted C-i-Cβ hydroxyalkyl or mercaptoalkyl c) an optionally substituted aminoalkyl group or an alkyl group substituted with a quaternary ammonium group

wherein R ₂, Rι₃, ₁4 are each independently a hydrogen atom or an optionally substituted alkyl, arylalkyl or aryl radical d) an optionally substituted cycloalkyl, arylalkyl or heterocyclyl-alkyl group e) a heterocyclyl group, wherein the heterocycle has a 5-6 membered, saturated or unsaturated ring and can contain supplementary heteroatoms, such as oxygen, sulfur and nitrogen f) an optionally substituted aryl group or g) R₃ and R4 form together an optionally substituted, 3-7 membered, saturated or unsaturated heterocyclic ring, which can contain supplementary heteroatoms, such as oxygen, sulfur or nitrogen, the nitrogen atom of the heterocyclic ring being optionally substituted with a Ci-Cβ alkyl , formyl, arylalkyl, aryl or heterocyclyl group or forming a quaternary ammonium salt.

2. A compound of the formula (I) as defined in Claim 1 wherein R1 is an (α-hydroxy)ethyl group.

3. A compound according to Claim 2 wherein R₃ and R₄ are hydrogen, optionally substituted Ci -Cβ alkyl, hydroxyalkyl, optionally substituted aryl, arylalkyl, heterocyclyl-alkyl.

4. A compound according to Claim 2 wherein R₃ and R4 are linked together in an optionally substituted heterocyclic ring, wherein the heterocycle is a saturated or unsaturated five or six atom ring system and can contain one or more additional heteroatoms, including N, O, S, such as 1-pyrrolidyl, 4-morpholyl or 1-piperazinyl, wherein the nitrogen atom in the position 4 of the piperazine ring can be optionally substituted with a Ci-Cβ alkyl, aryl, arylalkyl or heterocyclyl group.

5. A compound according to Claims 3 and 4 which is chosen from (5R,6S)-2-(N,N-dimethylamino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]- penem-3-carboxylate

^'(5R,6S)-2-(4-morpholinethiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3- carboxylate

(5R,6S)-2-(pyrrolidinethiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3- carboxylate

(5R,6S)-2-(aminothiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3- carboxylate (5R,6S)-2-(N-benzylamino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3- carboxylate

(5R,6S)-2-(N-methyl-N-benzylamino-thiocarbonylthiomethyl)-6-[( R)-1-hydroxyethyl]- penem-3-carboxylate

(5R,6S)-2-[(piperazin-1 -yl)-thiocarbonylthiomethyl]-6-[(1 R)-1 -hydroxyethyl]-penem-3- carboxylic acid

(5R,6S)-2-((4-methyl-piperazin-1 -yl)-thiocarbonylthiomethyl)-6-[(1 R)-1 -hydro xyethyl]- penem-3-carboxylate

(5R,6S)-2-((4,4-dimethyl-piperazin-1 -yl)-thiocarbonylthiomethyl)-6-[(1 R)-1 -hydroxy- ethyl]-penem-3-carboxylate

(5R,6S)-2-(N,N-dibenzylamino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]- penem-3-carboxylate

(5R,6S)-2-(N-phenylamino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]-penem-3- carboxylate

(5R,6S)-2-(N-methyl-N-phenylamino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxyethyl]- penem-3-carboxylate

(5R,6S)-2-[N-methyl-N-(2-pyridyl)thiocarbonylthiomethyl]-6-[(1 R)-1 -hydroxyethyl]- penem-3-carboxylate

(5R,6S)-2-[N-methyl-N-(2-(2-pyridyl)ethylamino-thiocarbonylthiomethyl]-6-[(1 R)-1- hydroxyethyl]-penem-3-carboxylate

(5R,6S)-2-(N,N-bis-(2-hydroxyethyl)amino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxy- ethyl]-penem-3-carboxylate

(5R,6S)-2-(N,N-bis-(2-acetyloxyethyl)amino-thiocarbonylthiomethyl)-6-[(1 R)-1- ^' hydroxyethyl]-penem-3-carboxylate

(5R,6S)-2-(N-methyl-N-benzyloxy)amino-thiocarbonylthiomethyl)-6-[(1 R)-1-hydroxy- ethyl]-penem-3-carboxylate

6. A compound according to Claim 1 wherein R₂ is a carboxy group esterified with any residue which is known to undergo metabolic activation in vivo and having favorable pharmacokinetic properties, including acetoxymethyl, pivaloyloxymethyl or any group of the general formula -COO-CH(R₅)-OCOOR₆ or -COO-CH₂-NHCOR₇

wherein R5, R6, R7 are alkyl having from 1 to 6 carbon atoms or aryl.

7. A process for the preparation of compounds of formula (I) according to Claim 1 , the process comprising: a) the synthesis of a compound of formula (V)

wherein R1 is as defined above in Claim 1 , COOY is an ester group and Z is alkyl or aryl, starting from the corresponding alcohol (II)

wherein R1 and Y are as defined above, by reacting compound (II) with the suitable sulfonyl chloride in the presence of an organic base, in an inert organic solvent, at a temperature ranging from -70° to +20°C. b) the reaction of the sulfonyl derivative (V) with an organic or inorganic salt of an optionally substituted carbamodithioic acid, in an organic solvent such as for example methyl sulfoxide, dimethyl formamide, dioxane or tetrahydrofuran, at a temperature ranging from -20° to +20°C. c) when necessary or desired, the removal of the protecting groups present in the product.

8. A pharmaceutical or veterinary composition containing a suitable carrier and/or diluent, and, as an active principle, a compound according to Claim 1 or a pharmaceutically or veterinarily acceptable salt thereof.

9. A compound of formula (I) as defined in Claim 1 or a pharmaceutically or veterinarily acceptable salt thereof, as an antibacterial agent.

10. Use of a compound of formula (I) as defined in Claim 1 , or a pharmaceutically or veterinarily acceptable salt thereof, for use in the production of a preparation for the treatment of the human or animal body by therapy.