DE1226591B - Process for the preparation of vicinal triazoles - Google Patents

Description

Process for the preparation of vicinal triazoles There are syntheses of v-Triazoles which are substituted on the N atoms are known. They are also v-triazoles described, the various groupings on the carbon atoms in the 4- and 5-position sluggish. Some of these compounds are only in very unsatisfactory yield and accessible by an arduous path. So far, however, are those v-triazoles that z. B. in the 5-position a cyano or acetyl group and optionally one in the 2-position carry substituted aryl nucleus, has not been described at all.

The process according to the invention for the preparation of vicinal triazoles of the general formula I. in which R1 is an acetyl, benzoyl or cyano radical, Rs is an optionally substituted aryl radical and R3 is a methyl or phenyl radical, consists in that a substituted glyoxaliminarylhydrazone of the general formula II in which R1, R2 and R3 have the meanings given above, is heated in alcoholic solution with an ammoniacal-aqueous copper (II) salt solution.

Good yields are achieved by the process according to the invention. By catalytic or dehydrating action of these copper complex compounds the two N atoms on the imino and on the hydrazo group are below Ring closure removed.

The products of the process are used in particular for the synthesis of medicinal products and of dye intermediates.

The invention is explained in more detail in the following process examples.

Example 1 2-Phenyl-4-phenyl-5; cyano-triazole- (1,2,3) 2 parts of ar-phenylazo-gamino-cinnamonitrile are dissolved in 50 parts of ethanol and treated with a solution of 2 parts of CuCl2 2 HsO combined in 10 parts of concentrated ammonia solution. The reaction mixture is Boiled for 30 minutes, sucked off the separated white crystal pulp and made of ethanol recrystallized. Yield 1.8 parts. White needles from m.p. 133 to 134 "C.

Example 2 5-Cyano-4-phenyl-2- (4-bromophenyl) -triazole- (1, 2,3) 2 parts or- (4-bromophenylazo) -B-amino-cinnamonitrile are boiling in 200 parts of alcohol dissolved and concentrated with a solution of 2.5 parts of CuCl2 2 H2O in 10 parts Ammonia solution added. After boiling for 1 hour, the reaction mixture has cooled down the precipitated triazole derivative filtered off with suction and recrystallized from ethanol. yield 1.8 parts, m.p. 1400 C.

Example 3 5-Acetyl-4-methyl-2-phenyl-triazole- (1, 2,3) 6 parts of 2-acetyl-1-methyl-glyoxal-imide- (1) -phenylhydrazone- (2) are dissolved in 60 parts of boiling methanol, with a solution of copper salt in concentrated aqueous ammonia solution and heated under reflux. the after the reaction solution has cooled, precipitated white crystals are dissolved in ethanol dissolved, and after acidification with dilute HCl, the triazole is precipitated with water with simultaneous separation of impurities such. B. Copper Salts. It will recrystallized from ethanol and falls in good yield in the form of snow-white needles from m.p. 54 ° C on.

Example 4 5-Acetyl-4-methyl-2-p-tolyl-triazole41, 2,3) 6 parts of 2-acetyl- 1-methyl-glyoxalimide- (1) -p-tolylhydrazone- (2) are dissolved in 100 parts of methanol, and mixed with an ammoniacal copper salt solution. The reaction mixture is Boiled under reflux for 1 hour and, as indicated in Example 3, worked up. After recrystallization, the triazole becomes in good yield in the form of snow-white needles obtained from m.p. 930C.

Example 5 5-Acetyl-4-methyl-2- (4bromophenyl) -triazole- (1, 2,3) 8.5 Parts of 2-acetyl-1-methyl-glyoxalimide41) -p-bromophenylhydrazone- (2) are in 250 parts Dissolved ethanol and mixed with an ammoniacal copper salt solution. After an hour The reaction is over when boiling. The precipitated triazole is, as in example 3 described, isolated and purified and in good yield after recrystallization from methanol in the form of white crystals of mp.

109 "C received.

Example 6 5-Benzoyl-4-methyl-2-phenyl-triazole41, 2,3) 2 parts of 2-benzoyl-1 -methyl-glyoxalimide- (1) -phenylhydrazone- (2) are dissolved in 20 parts of ethanol and mixed with an ammoniacal solution of copper salt. The reaction mixture is refluxed for 1112 hours. After the reaction solution has cooled down precipitated pale yellow colored triazole derivative is, as indicated under Example 3, purified and after recrystallization from ethanol forms white needles of mp. 74 "C.

Example 7 5-Benzoyl (methyl-244-chlorophenyl) -triazole- (1, 2,3) 1 part 2-Benzoyl-1-methyl-glyoxalimide- (1) + chlorophenylhydrazone- (2) are dissolved in 30 parts of ethanol solved and mixed with an ammoniacal copper salt solution. The reaction mixture is refluxed for a few minutes. After cooling, the precipitated triazole derivative, as stated in Example 3, isolated and after recrystallization from ethanol obtained in good yield in the form of white needles with a melting point of 106 "C.

Claims (1)

Claim: Process for the production of vicinal triazoles of the general formula 1 in which R1 is an acyl, benzoyl or cyano radical, R2 is an optionally substituted aryl radical and R3 is a methyl or phenyl radical, characterized in that a substituted glyoxaliminarylhydrazone of the general formula II in which R1, R2 and R3 have the meanings given above, is heated in alcoholic solution with an ammoniacal-aqueous copper (II) salt solution. Publications considered: Chimica, 17 (1963), No. 5, pp. 159/160.