Patent ID: 8519148

Claim:
A process for preparing a chirally purified substituted 4,5,6,7-tetrahydro-benzothiazole diamine comprising: heating a solution to a temperature of from about 50° C. to about 125° C., the solution comprising enantiomerically enriched 4,5,6,7-tetrahydro-benzothiazole diamine of formula (1): wherein: R1 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl or alkynyl group each having 3 to 6 carbon atoms, an alkanoyl group having 1 to 6 carbon atoms, a phenyl alkyl or phenyl alkanoyl group having 1 to 3 carbon atoms in the alkyl part; R2 is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; R3 is a hydrogen atom, an alkyl group with 1 to 7 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an alkenyl or alkynyl group having 3 to 6 carbon atoms, an alkanoyl group having 2 to 7 carbon atoms, a phenyl alkyl or phenyl alkanoyl group having 1 to 3 carbon atoms in the alkyl part, R4 is a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, an alkenyl or alkynyl group having 3 to 6 carbon atoms; and at least one or R1, R2, R3 or R4 is a hydrogen in an organic solvent; and an alkyl sulfonate or an alkyl halide in a solvent to form a reaction mixture; reacting the reaction mixture at a temperature of from about 50° C. to about 125° C.; and recovering a chirally purified substituted 4,5,6,7-tetrahydro-benzothiazole diamine.