An Entry to 5-(1-Alkenyl)-3(2H)-furanones through Cycloaddition of Phosphorus-Functionalized Nitrile Oxide to Acetylene Alcohols. An Effective Synthesis of Geiparvarin

Abstract
Cycloaddition of α-(diethoxyphosphoryl)acetonitrile oxide to acetylene alcohols is followed by an alkylation, a reductive cleavage of the N–O bond, and an acid-catalyzed cyclization to form 5-(diethoxyphosphorylmethyl)-3(2H)-furanones in good yields. Subsequent Horner-Emmons olefination using triethylamine and lithium bromide furnishes E-isomers of 5-(1-alkenyl)-3(2H)-furanones as major products. This method has been applied to a short synthesis of Geiparvarin.