Lewis Acid-Promoted Three-Component Cyclization for the Construction of Functionalized Oxazoles

Abstract

A simple and efficient synthetic strategy from amides, ynals, and sodium sulfinates via a Lewis acid-promoted threecomponent reaction has been reported. Thus, a broad range of various aryl (not alkyl)-substituted oxazoles could be synthesized via the formation of C−N, C−O, and C−S bonds in a one-pot process. In addition, this reaction possesses other unique advantages, such as transition metal-free catalysis, high step economy, good functional group tolerance, and good regioselectivity.

Synthesis of N-, O-, and S-heterocycles from aryl/alkyl alkynyl aldehydes

“…Very recently, another interesting type of Lewis acid catalyzed the construction of 2,5-disubstituted oxazoles 60b was reported by Zhu and Cao et al ( Scheme 83 ). 96 Broad substrate scope including propargyl aldehydes 1a, aromatic amides 60a, and aryl/alkyl-substituted sodium sulfonates 5a worked well in this metal-free cyclization reaction. The reaction proceeded via the formation of intermediate A, the addition of 5a into A, and 5- exo -dig cyclization.…”