Cyclic hydroxycarboxylic acids. IV. Synthesis of 2,3-cis-2,3-Dihydroxycyclopentanecarboxylic acid derivatives

Abstract

cis-α-Glycolation with KMnO4 or OsO4 of methyl cyclopent-2- enecarboxylate yields mixtures of methyl c-2,c-3- and t-2,t-3- dihydroxycyclopentane-r-1-carboxylates which are difficult to separate. The derived dihydroxy acids and their acetonides, and the acetonides, diacetates, bis-trifluoroacetates, and ditosylates of the esters are characterized as mixtures in the two diastereomeric families that have defied usual preparative separation procedures. None of the products is crystalline, and only some of them show two components by g.l.c. or p.m.r. examination, so close is their polarity.