Novel Crossed Diels—Alder Reactions of 1-(2-Butadienyl)pyridinium Bromide

摘要

Crossed Diels-Alder cycloadditions of a positively charged diene, 1-(2-butadienyl)pyridinium bromide (1a), with cyclopentadiene in acetonitrile proceed stereospecifically and regioselectively. The regioselectivity of la as the dienophile is especially unique.