A simple approach to highly stereoselective synthesis of beta,gamma-trans-gamma-butyrolactones

A simple approach to highly stereoselective synthesis Of trans-beta-methoxy carbonyl-gamma-aryl-gamma-butyrolactones (5a-5c) is reported. Methoxycarbon ylmethyltriphenylarsonium bromide (1) in dimethyl ethylene glycol was react ed with 2,2-dimethyl-1,3-dioxa-5-p-methoxybenzal-4, 6-dione(2a) in the pres ence of K2CO3 and trace of water at room temperature, to give trans-beta-me thoxycarbonyl-gamma-p-methoxyphenyl- gamma-butyrolactone (5a) with 64 % yie ld, whereas 1,2-cis cyclopropane derivatives(3b and 3c) were isolated when started from 2b or 2c, under same conditions. The gamma-butyrolactones 5b o r 5c were obtained with 62% and 57% yields when compounds 3b or 3c was furt her heated in acetone-water. The structures of 5a-5c were established on th e basis of IR, H-1 and C-13 NMR, MS and elemental analyses, and their confi gurations were assigned via 2D proton NOESY spectrum of compound 5c.