Generation of ortho-Quinone Methides by p-TsOH on Silica and Their Hetero-Diels-Alder Reactions with Styrenes

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).