Synthesis of (2R)- and (2S)- [1-13C]-2-amino-2-methylmalonic acid: Chiral substrates for serine hydroxymethyltransferase

Abstract

(2R) - and (2S)-[1-13C]-2-amino-2-methylmalonate, probes for the stereochemical course of the serine hydroxymethyltransferase reaction, have been synthesised from bis-lactim ethers derived from valine and alanine. Direct acylation of the anion with diethyl carbonate gave the N-ethoxycarbonyl derivative rather than the required ethyl ester. The 13C-labelled carboxyl group was therefore Introduced via treatment of the anion with [1-13C]-acetyl chloride, followed by haloform oxidation. The resulting carboxylate salt was then esterified with methyl iodide, and the bis-lactim ether ring system was cleaved under acidic conditions to give the amino acid esters. Saponification and then separation by cation exchange chromatography gave the title compounds. © 1991.