Esterase-mediated synthesis of optically active GABA analogues containing a stereogenic all-carbon quaternary carbon atom.

Esterase from Horse Liver (HLAP) was able to hydrolyze a series of linear and cyclic b,b-dialkyl-c-nitroesters, in spite of the well-known reluctance of hydrolytic enzymes to recognize and transform hindered substrates, such as those possessing a stereogenic quaternary carbon atom next to the reaction site. The resulting optically active c-nitroesters gave access to optically active b,b-disubstituted c-aminoacids as well as a,a-disubstituted succinic acids, both being biologically relevant compounds