Diastereomerically pure rarely functionalized alkenoyl dihydropyrans, 1,6-diketones, and cyclopentanes from acetylene gas and ketones

Abstract

Pure (E)-alkenoyl dihydropyrans are stereoselectively assembled from 2-acetyl-3,4-dihydropyrans (products of one-pot self-organization of acetylene gas and ketones) and aromatic aldehydes (52–86% yields). Furthermore, (E)-alkenoyl dihydropyrans undergo ring opening (acid hydrolysis) to afford 5-hydroxy-1,6-diketones (44–67% yields) and acetyl-2-(E)-styryl-2,3-dihydroxycyclopentanes (19–32% yields), both as single diastereomers.