The resolution of the enantiomers of the chemotherapeutic Ornidazole (
Tiberal((R))) 1a was achieved by acetylation of the racemic compound w
ith vinylacetate in the presence of lipase Amano PS (from Pseudomonas
cepacia). The halogen analogues 4a-6a and the corresponding 4-nitro-de
rivatives 1b and 4b-6b were also synthesized and the enantiomers were
separated by kinetic enzymatic resolution. The absolute configuration
of two compounds was determined by X-ray crystallography. (C) 1997 Els
evier Science Ltd.