3,4-Dihydro-2H-pyran (DHP) was efficiently transformed into 4-thiophenyl-3,4-dihydro-2H-pyran. This intermediate was converted to the corresponding 1,3-O,Sallylic carbanion with t-butyllithium and selectively alkylated at the carbon a to the sulfur with alkyl halides, an epoxide, and an aldehyde. An one-pot oxidative elimination of the sulfur fragment using vanadium pentoxide generates the desired beta-substituted alpha,beta-unsaturated delta-unsaturated-valero lactone.
3,4-Dihydro-2H-pyran (DHP) was efficiently transformed into 4-thiophenyl-3,4-dihydro-2H-pyran. This intermediate was converted to the corresponding 1,3-O,Sallylic carbanion with t-butyllithium and selectively alkylated at the carbon a to the sulfur with alkyl halides, an epoxide, and an aldehyde. An one-pot oxidative elimination of the sulfur fragment using vanadium pentoxide generates the desired beta-substituted alpha,beta-unsaturated delta-unsaturated-valero lactone.