Stereospecific synthesis of α-deuteriated α-amino acids: regiospecific deuteriation of chiral 3-isopropyl-2,5-dimethoxy-3,6-dihydropyrazines

Abstract

Base-catalysed deuteriation of (3R)- or (3S)-3-isopropyl-2,5-dimethoxy-3,6-dihydropyrazines in refluxing CH₃O²H–²H₂O gives the [6-²H₂]-isotopomer in excellent yields without disturbing the stereogenic centre at C-3. These compounds provide convenient and efficient access to a range of (R)- and (S)-α-deuteriated α-amino acids, including serine, aspartic acid, allylglycine and phenylalanine, via alkylation of the butyllithium generated C-6 anion.