Chiral 1,4-Dicarbonyl-2,3-O-Isopropylidene Derivatives. Rapid Racemization on Standing

RODRIGUEZ, JUAN BAUTISTA

TETRAHEDRON

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1999 vol. 55 p. 2157 - 2170

0040-4020

1,4-Dicarbonyl-2,3-chiral derivatives are useful synthetic precursors for the preparation of carbocyclic rings but, in many cases, losses of optical purity have been reported. 1-Deoxy-3,4-O-isopropylidene-6-O-trityl-D-erythro-hexo-2,5-diulose and 1-deoxy-3,4-O-isopropylidene-6-O-(tert-butyldiphenylsilyl)-D-erythro-hexo-2,5-diulose were synthesized from D-ribono-1,4-lactone. These compounds were selected to study the epimerizability of 2,3-O-isopropylidene-1,4-dicarbonyl derivatives. It was found that both compounds smoothly epimerize and partially racemize on standing.