Efficient synthesis of (S)-3,4-dihydro-2-pivaloyloxymethyl-2H-pyrrole 1-oxide
A convenient synthesis of the title nitrone is reported. The sequence starts from ethyl L-pyroglutamate as the source of chirality and the key step is the generation of an unstable α-methoxy-N-carboxylate ion, which readily decomposes to an imine. The oxidation of the imine with methyl(trifluoromethyl)dioxirane provides the enantiopure nitrone, which is trapped with dimethyl acetylenedicarboxylate.