Mild Pd(OAc)2/PPh3 catalyzed cyclization reactions of 2-vinylazetidines with heterocumulenes: An atom-economy synthesis of tetrahydropyrimidinone, tetrahydropyrimidinimine, and thiazinanimine analogs

Abstract

A versatile method for the reaction of N-alkyl-2-vinylazetidines with heterocumulenes has been established using a Pd(OAc)2/PPh3 catalyst system at room temperature. Minor modifications in the design of either substrate allowed for the optimization of product yield. Evidence for π-allylpalladium formation was obtained from the reaction of trans-1-butyl-4-methyl-2-vinylazetidine, which afforded a cis/trans mixture of products arising from stereochemical inversion through η3-η1-η3 isomerization.