Evolution of Natural Product Scaffolds by Acyl- and Arylnitroso Hetero-Diels−Alder Reactions: New Chemistry on Piperine

Piperine, a natural product containing a conjugated diene, was reacted with polymer-supported acyl- and arylnitroso dienophiles. The reactions with arylnitroso dienophiles were also carried out in solution. The oxazine rings formed by the corresponding hetero-Diels−Alder reactions were further transformed and novel acyclic as well as heterocyclic derivatives including pyrroles and quinoxalinones were prepared.