Synthesis of Functionalized 2H-1-Benzopyrans by DBU-Catalyzed Reactions of Salicylic Aldehydes with Allenic Ketones and Esters

DBU-catalyzed reactions of salicylic aldehydes with 3-methylpenta-3,4-dien-2-one, 3-benzylpenta-3,4-dien-2-one, or ethyl 2-methylbuta-2,3-dienoate gave the corresponding functionalized 2H-1-chromenes in good to excellent yields and good diastereoselectivities in some cases in DMSO, respectively.