FACILE CONVERSION OF NATURAL COLCHICINE INTO (+/-)-CONGENERS AND (+)-ENANTIOMERS INCLUDING 2-DEMETHYL ANALOGS

Racemization of natural colchicine in refluxing acetic anhydride afforded after hydrolysis and chemical manipulation a variety of (±)-colchicinoids. Optical resolution of (±)-deacetylcolchicine and (±)-deacetylisocolchicine afforded the respective optical isomers, readily converted by N-acetylation into (-)- and (+)-colchicine and (-)-and (+)-isocolchicine. Selective ether cleavage of (±)- and (-)-colchicinoids with concentrated sulfuric acid afforded 2-demethyl analogues as major products. A single-crystal X-ray analysis of (±)-l showing unusual physical properties is reported. © 1986, American Chemical Society. All rights reserved.