Unusual tandem sequence of oxa Diels–Alder reaction, retro Diels–Alder reaction, and oxa 6π-electrocyclic ring opening in the reaction of 6-amino-4-(4-methoxyphenyl)-2H-pyran-2-ones with benzaldehydes

Abstract

The oxa Diels–Alder reaction of 6-amino-4-(4-methoxyphenyl)-2H-pyran-2-ones with benzaldehydes took an unusual path whereby an unexpected tandem sequence of three reactions yielded 3-(4-methoxyphenyl)-5-phenyl-1-(piperidin-1-yl/pyrrolidin-1-yl)penta-2,4-dien-1-ones.