RU2356905C1 - Method of obtaining optically active (1s,2s)-1,7,7-trimethyl-2-[(dichloroaluminium)oxy]bicyclo[2,2,1]heptane - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to organic synthesis, more specifically to the method of obtaining a new aluminium derivative - (1S,2S)-1,7,7-trimethyl-2-[(dichloroaluminium)oxy]bicyclo[2.2.1]heptane, which can be used thin organic and metalorganic synthesis, obtaining enantiomerically pure products with high optical output. The method involves reaction of (1S,2S)-1,7,7-trimethyl-bicyclo[2.2.1]heptan-2-ol with ethyl aluminium dichloride (EtAlCl₂) in an argon atmosphere at normal pressure in benzol medium for 1.0-3.0 hours.

EFFECT: 80-94% output of target products.

1 cl, 1 ex, 1 tbl

Description

The present invention relates to methods for producing new derivatives of aluminum, specifically to a method for producing optically active

(1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane of the general formula (I):

The proposed method can find application in fine organic and organometallic synthesis, in particular in the production of enantiomerically pure products with high optical yields.

The known method ([1] G. Giacomelli, L. Bertero, L. Lardicci. Nickel Catalyzed Stereodifferentiating Displacement Reaction Between Prochiral 1 - Alkenes and Optically Active Organoaluminium Solvates // Tetrahedron Lett., V.22, 1981, p.883-886 ) obtaining optically active organoaluminum compounds (2) by reacting disubstituted terminal alkenes with triisobutylaluminum in the presence of Ni-containing catalysts and chiral ligands at room temperature for 40 hours according to the scheme:

In a known manner, the optically active (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1) cannot be obtained.

The known method ([2] MLSierra, R. Kumar, V. Srini, J. Mel, JP Oliver. Synthesis and Spectroscopic Investigations of Alkylaluminium Alkoxides Derived from Optically Active Alcohols // Organometallics, v.11, 1992, p.206- 214) obtaining optically active aluminum alkoxides (3) by the interaction of trialkylalanes with optically active alcohol at room temperature according to the scheme:

The known method does not allow to obtain optically active (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1).

Thus, there is no literature information on the regioselective synthesis of optically active (1S, 2S) -l, 7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1).

A method is proposed for producing new types of optically active organoaluminum compounds, namely (1S, 2S) -1,7,7-tremethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1).

The proposed method is carried out by the interaction of (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptane-2-ol with ethyl aluminum dichloride (EtAlCl ₂ ), taken in a molar ratio of 10: (10-14), preferably 10:12 in an argon atmosphere at room temperature (20-21 ° C) and atmospheric pressure in benzene. The reaction time is 1.0-3.0 hours, preferably 2 hours. The yield of the (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane dimer complex is 80-94%. The reaction proceeds according to the scheme:

Optically active (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1) is formed only with the participation of (1S, 2S) -1,7,7 -trimethylbicyclo [2.2.1] heptan-2-ol and ethyl aluminum dichloride (EtAlCl ₂ ). In the presence of other chiral alcohols or other aluminum compounds (e.g., AlEt ₃ , AlBu ⁱ ₃ , Et ₂ AlCl, EtAlCl ₂ ), the desired product (1) does not form.

A change in the ratio of the starting reagents in the direction of increasing the EtAlCl ₂ content with respect to (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptan-2-ol does not lead to a significant increase in the yield of the target product (1). The syntheses were carried out at room temperature (20-21 ° C). At a higher temperature (for example, 40 ° C), an increase in the yield of the target products is not observed, and at a lower temperature (for example, 0 ° C), the reaction rate decreases.

Significant differences of the proposed method:

In the proposed method, ethyl aluminum dichloride (EtAlCl ₂ ) and optically active (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptan-2-ol are used as starting reagents. In the known method, trialkylalanes (AlR ₃ ) and optically active 5-methyl-2- (1-methylethyl) cyclohexanol are used as starting reagents.

The proposed method has the following advantages:

1. The method allows to obtain with high regioselectivity the optically active (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (1), the synthesis of which is not described in the literature.

The method is illustrated by the following examples.

Example 1. In a 50 ml glass reactor mounted on a magnetic stirrer, 12 mmoles of EtAlCl ₂ in 20 ml of C ₆ H ₆ are placed under argon atmosphere. To this mixture, 10 mmoles of (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptan-2-ol are added in small portions, stirred for 2 hours at room temperature (20-21 ° C). Obtain (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane in 89% yield. [α] _D ²⁰ = -6.69 ° (C = 11.72, C ₆ H ₆ ).

NMR spectrum ¹³ C (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane (δ, ppm, 22.5 MHz, C ₆ D ₆ ): 87.18, 50.05, 48.43, 44.90, 39.17, 27.68, 26.17, 20.25, 18.15.

Other examples confirming the method are given in table.

No. p / p The molar ratio of EtAlCl ₂ : (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptan-2-ol, mmol Reaction time, h The yield of the target product (1),% one
2
3
four
5 12:10
10:10
14:10
12:10
12:10 2
2
2
3
one 89
81
94
92
80

The reactions were carried out at room temperature (20-21 ° C) in benzene.

Claims (1)

The method of obtaining optically active (1S, 2S) -1,7,7-trimethyl-2 - [(dichloralumin) oxy] bicyclo [2.2.1] heptane of the formula (1)

characterized in that (1S, 2S) -1,7,7-trimethylbicyclo [2.2.1] heptan-2-ol interacts with ethyl aluminum dichloride (EtAlCl ₂ ) in a molar ratio of 10: (10-14) in argon atmosphere at normal pressure in benzene for 1.0-3.0 hours