No activation barrier synthetic route of glycine from simple molecules (NH3, CH2, and CO2) via carboxylation of ammonium ylide: a theoretical study by the scaled hypersphere search method

A new synthetic route of glycine with no activation barriers, NH3 + CH2 + CO2 → H2NCH2COOH, has been discovered by the scaled hypersurface search method for ab initio potential energy surfaces. The route is composed of two steps with no activation barriers, an addition reaction of ammonia with singlet methylene yielding ammonium ylide (NH3 + 1:CH2 → H2CNH3) followed by carboxylation of the ylide with carbon dioxide (H2CNH3 + CO2 → H2NCH2COOH). A sideway reaction of the ylide decomposing into methyleneimine and hydrogen (H2CNH3 → H2CNH + H2) via new transition state was found in addition to an isomerization route to methylamine (H2CNH3 → CH3NH2).