The morita-baylis-hillman reaction of chiral highly oxygenated cyclopent-2-enones

Abstract

The Morita-Baylis-Hillman (MBH) reactions of (4S,5R,7R,8R)- and (4R,5R,7R,8R)-4-hydroxy-7,8-dimethoxy-7,8-dimethyl-6,9-dioxaspiro[4.5] dec-2-en-1-ones (2 and 3, resp.) with aldehydes using various catalysts were studied. A combination of Bu 3 P/phenol in THF was found being optimum conditions giving the corresponding MBH adducts with high diastereoisomeric ratios. After separation, each stereomerically pure isomer of the MBH adducts was subjected to hydrolysis employing 1% aq. CF 3 COOH (TFA) in a water bath of an ultrasonic cleaner to afford the corresponding polyhydroxylated cyclopentenones in good yields. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich, Switzerland.