Reactivity of UNCAs with Grignard reagents

Abstract

The reactivity of Grignard reagents with UNCAs (Urethane N-protected Carboxyanhydrides of Amino acids) is described. We observed that, depending on the method of addition of the organometallic compounds, the reaction proceeded differently: (i) when the UNCA was added to the Grignard reagent, we obtained a mixture of five different products which were all identified; and (ii) when the organometallic reagent was added to the UNCA, we also obtained a mixture of the same products but in different proportions, with the major component corresponding to the urethane N-protectedN-acyl amino acid derivative.