Generation of <i>ortho</i>-Quinone Methides by <i>p</i>-TsOH on Silica and Their Hetero-Diels−Alder Reactions with Styrenes

Abstract

2-Arylchromans were readily prepared from the hetero-Diels-Alder reactions of styrenes with the ortho-quinone methides (o-QMs) which, in turn, were generated by treating the MOM-protected benzylacetate derivatives with p-TsOH immobilized on silica (PTS-Si) in toluene under mild conditions (0 degrees C to rt). The corresponding chromans were obtained in moderate to excellent yields (42-97%) and in moderate to excellent diastereoselectivity (up to >99:1).