Efficient asymmetric synthesis of the functionalized pyroglutamate core unit common to oxazolomycin and neooxazolomycin using Michael reaction of nucleophilic glycine Schiff base with α,β-disubstituted acrylate

Abstract

The functionalized pyroglutamate core unit, (2 R,4 R)- 3, which could be converted into the β-lactone/pyrrolidine or γ-lactone/pyrrolidine ring system of oxazolomycin A 1 and neooxazolomycin 2, and which possesses an exomethylene group at C3 as a scaffold for the construction of their C3 polyene segment, was synthesized by the Michael reaction of a glycine Schiff base 4 with the α,β-disubstituted acrylate 8 as the key step.