Optically active 1,4-benzodiazepines and process for the preparation thereof

A process for preparing an optically active compound having the formula ##STR28## having an asymmetric carbon atom in position 3 said asymmetric carbon atom having the S configuration wherein R.sub.1 is selected from the group consisting of hydrogen, halogen, nitro, and trifluoromethyl, R.sub.2 is selected from the group consisting of hydrogen and C.sub.1-4 lower alkyl, and R.sub.3 is selected from the group consisting of C.sub.1-4 lower alkyl, hydroxy C.sub.1-4 lower alkyl, phenyl, hydroxy phenyl, benzyl, hydroxy benzyl, and 3'-methyleneindolyl, comprising the steps of

• a. reacting a compound having the formula ##STR29## wherein R.sub.1 and R.sub.2 have the same meaning as was defined in formula I, in an inert solvent, selected from the group consisting of methylene chloride, tetrahydrofuran and mixtures thereof with a compound having the formula ##STR30## in the presence of dicyclohexylcarbodiimide and wherein R.sub.3 has the same meaning as for the compound having formula I, and A is a protective group selected from the group consisting of carbobenzoxy and t-butoxy carbonyl, to form an intermediate compound having the formula ##STR31## b. removing said protective group by acidic hydrolysis by treatment with HBr in acetic acid, HBr in methanol or mixture of 1:1 acetic acid in ethanol in an inert solvent at a temperature no greater than about room temperature, and
• c. cyclizing the compound of formula IV having its protective group removed in an inert solvent selected from the group consisting of water, a methanol-water mixture and the ethanol-water mixture at a pH of about 8.5 at a temperature no greater than about 40.degree. C.

A process for preparing an optically active compound having the formula ##STR32## having an asymmetric carbon atom in position 3 said asymmetric carbon atom having the S configuration wherein R.sub.1 is selected from the group consisting of hydrogen, halogen, nitro, and trifluoromethyl, R.sub.2 is selected from the group consisting of hydrogen and C.sub.1-4 lower alkyl and R.sub.3 is selected from the group consisting of C.sub.1-4 lower alkyl, hydroxy C.sub.1-4 lower alkyl, phenyl, hydroxy phenyl, benzyl, hydroxy benzyl and 3'-methyleneindolyl, comprising the steps of

• a. reacting a compound having the formula ##STR33## wherein R.sub.1 and R.sub.2 have the same meaning as was defined in formula I, in an inert solvent, selected from the group consisting of methylene chloride, tetrahydrofuran and mixtures thereof with a compound having the formula ##STR34## in the presence of dicyclohexylcarbodiimide and wherein R.sub.3 has the same meaning as for the compound having formula I, and A is a protective group selected from the group consisting of carbobenzoxy and t-butoxy carbonyl, to form an intermediate compound having the formula ##STR35## b. removing the protective group by catalytic hydrogenolysis in an inert solvent selected from aqueous methanol and dioxane:
• ethanol mixture at a temperature no greater than room temperature, and
• c. cyclizing the compound of formula IV having its protective group removed in an inert solvent at a pH of about 8.5 at a temperature no greater than about 40.degree. C.