Pyroglutamic acid in drug synthesis, part 1: A method for the synthesis of enantiomerically pure 4-alkyl-4-arylpyroglutamic acids

Article abstract of DOI:10.1002/ardp.19963290108

Synthesis of the title compounds is described, starting from alkylation of the pyroglutaminol-acetal 4a^[1] at the α-lactam position C-6 with methyl iodide. Subsequent addition of 2-cyclohexen-1-one led to diastereoselective formation of the 1,2-aldol addition product 7b/7c, which after dehydratization was aromatized with DDQ to yield the 6-methyl-6-phenyl derivative 7h, Acetal cleavage and Jones oxidation yielded 4,4-disubstituted, enantiomerically pure pyroglutamic acid 3b. X-ray analysis confirmed the assignment of the configuration of the newly created chiral centre.