Novel domino products from the reaction of phenyl vinyl ketone and its derivatives with cyclic ketones

Reaction of phenyl vinyl ketone with cyclopentanone under thermal conditions resulted in novel domino products, 1,5,9-triketones along with the expected 1,5-diketones. The 1,5,9-triketones were formed via a Michael–Michael-rearrangement pathway. On the other hand, reaction under basic conditions furnished a spiro[4.5]decanone, formed by domino pathways involving Michael–Michael-aldol condensation reactions. Microwave mediated reductive amination–cyclization of the 1,5,9-triketone furnished the perhydrocyclopenta[ij]quinolizine derivative.