Diene-Transmissive Hetero Diels–Alder Reactions of 3-Oxo-1,4-pentadiene Equivalents Leading to Functionalized 2-Chromanones

Abstract

Through hetero Diels–Alder reaction with a vinyl ether and Horner–Emmons olefination, diethyl 2-oxo-3-butenylphosphonate leads to 2-ethoxy-6-(1-alkenyl)-3,4-dihydro-2H-pyrans which are further transformed into 2-chromanones via regioselective Diels–Alder reactions with activated acetylenes followed by hydrolysis and oxidation.