Potential GABA B Receptor Antagonists. IX The Synthesis of 3-Amino-3-(4-chlorophenyl)propanoic Acid, 2-Amino-2-(4-chlorophenyl)ethylphosphonic Acid and 2-Amino-2-(4-chlorophenyl)ethanesulfonic Acid

Abstract

This paper describes the synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid and the corresponding phosphonic and sulfonic acids, lower homologues of baclofen, phaclofen and saclofen respectively. The chlorinated acids were all weak specific antagonists of GABA at the GABA_B receptor, with the sulfonic acid (pA₂ 4·0) being stronger than the phosphonic acid (pA₂ 3·8) and carboxylic acid (pA₂ 3·5).