Rapid syntheses of benzopyrans from o-OBOC salicylaldehydes and salicyl alcohols: a three-component reaction.

The Diels-Alder reactions of o-quinone methides generated from OBOC-salicylic aldehydes and alcohols are described, allowing for the synthesis of various substituted benzopyrans. The low temperatures employed for this procedure enable high diastereoselectivity in reactions with beta-substituted o-quinone methides.