Aminative annulation of cyano-enynyl esters leading to functionalized cyclopentenones.

A base-mediated unexpected aminative carbo-cyclization of cyano-enynyl esters, generated from Morita-Baylis-Hillman (MBH) acetates of propiolaldehydes, with secondary-amines is described. This metal-free reaction allows the synthesis of a unique cyclopentenone bearing an exocyclic double bond (cyano-olefin) with high E -selectivity in good yields. The synthetic potential of this annulation was further exemplified by the derivatization of bioactive molecules, a scale-up synthesis and synthetic transformations of the obtained cyclopentenone.