Process of the preparation of chiral nicotinic, quinolinic or benzoic acid imidazolinone herbicides

A process for the preparation of a chiral compound of formula I

• wherein
• X is CH;
• and
• Y and Z are each independently H, C1-C4alkyl optionally substituted with one C1-C4alkoxy group or Y and Z may be taken together to form a group —CH═CH—CH═CH—
• which process comprises the following steps:
• a) reacting a compound of formula II
• wherein X, Y and Z are as described hereinabove with at least one molar equivalent of chiral 2-amino-2,3-dimethylbutyronitrile
• in the presence of a non-polar, essentially water-free solvent, optionally in the presence of a tertiary amine, to form a first reaction mixture;
• b) hydrolyzing said reaction mixture in aqueous acid to form an acidic second reaction mixture;
• c) reacting said second reaction mixture with an excess of an aqueous base at a temperature of about 15° C. to 90° C. to form a basic third reaction mixture;
• d) separating said third reaction mixture to obtain an aqueous phase;
• and
• e) acidifying said aqueous phase to obtain the desired chiral formula I imidazolinone compound.