The synthesis of diastereo- and enantiomerically pure β-aminocyclopropanecarboxylic acids

The synthesis of diastereo- and enantiomerically pure beta -aminocyclopropanecarboxylic acids (beta -ACCs) is described. Starting from pyrrole, (rac)-4 is readily obtained, which was kinetically resolved by enzymatic hydrolysis. Subsequent oxidation of (-)-4 and deformylation gives rise to:the cis-beta -ACC derivative (ent)-9, while (+)-10 was converted to the trans-beta -ACC derivative 8. Both 8 and (ent)-9 and their benzyl esters 13 and is, being conformationally restricted beta -alanine or gamma -aminobutyric acid (GABA) derivatives, represent useful building blocks for peptides containing unnatural amino acids.