PPh3-catalyzed intramolecular cyclization of hydroxypropargylamides: Synthesis of structurally diverse morpholinone derivatives

Abstract

The metal-free synthesis of substituted morpholinones through a sequential intramolecular post-Ugi cyclization strategy is described. In the subsequent step, Ugi adducts hydroxy propargylamides derivatives undergo chemo- and regioselective 6-exo-dig catalytic cyclization to afford O-cyclized products in the presence of triphenylphosphine. This sequence offers an engrossing functionalized morpholinone scaffold involving moderate reaction conditions with broad substrate scope and moderate to good yields.