Non-precious metal carbamates as catalysts for the aziridine/CO2 coupling reaction under mild conditions

Abstract

The catalytic potential of a large series of easily available metal carbamates (based on thirteen different non-precious metal elements) was explored for the first time in the coupling reaction between 2-aryl-aziridines and carbon dioxide, working under solventless and ambient conditions and using tetraalkylammonium halides as co-catalysts. The straightforward synthesis of novel [NbCl₃(O₂CNEt₂)₂], Nb^Cl, and [NbBr₃(O₂CNEt₂)₂], Nb^Br, is reported. The niobium complex Nb^Cl, in combination with NBu₄I, emerged as the best catalyst of the overall series to convert aziridines with small N-alkyl substituents into the corresponding 5-aryl-oxazolidin-2-ones.