Improved stereoselective synthesis of optically active methylene lactone, key intermediate for the synthesis of 1,2-oxidized furofuran lignan, by direct alpha-methylenation to butanolide.
(3R)-3-[(1R)-1-(tert-Butyldimethylsilyl)oxy-1-(2-methoxy-4,5-methylenedioxyphenyl) methyl]-2-methylene-4-butanolide, which is a key intermediate for the synthesis of 1,2-oxidized furofuran lignan, was stereoselectively synthesized from L-glutamic acid by applying direct methylenation to butanolide.