Improved Synthesis of Racemate and Enantiomers of Taniguchi Lactone and Conversion of Their C–C Double Bonds into Triple Bonds

Abstract

cis-2-Butene-1,4-diol was heated with triethyl orthoacetate and p-hydroquinone as catalyst at 170 °C to give racemic Taniguchi lactone. It was converted into diastereomeric amides with (S)-1-phenylethylamine for stereoisomer resolution. The double bonds of (±)-, (R)- and (S)-Taniguchi lactones were brominated and dehydrobrominated in two steps, using at first DBU and then LDA, to deliver the triple bonds.