Synthesis of β2,2-Amino esters via Rh-Catalysed Regioselective Hydroaminomethylation

The synthesis of beta(2,2)-amino esters was successfully achieved via Rh-catalysed regioselective hydroaminomethylation of methyl methacrylate with secondary amines using the neutral precursor [Rh(acac)(CO)(2)]. In this process, the presence of molecular sieves revealed crucial in order to access the final amino ester. For the synthesis of products containing aniline derivatives, the use of the cationic precursor [Rh(COD)(2)]BF4 and (Me)CgPPh phosphine as ligand was necessary in a mixture of toluene/DCE as solvent. Effects of the steric and electronic properties of the amines were observed during this study. Interestingly, poisoning effect of CO in the hydrogenation of the imine intermediate was observed when benzyl amine was used.