L-Proline and related chiral heterocyclic amino acids as scaffolds for the synthesis of functionalized 2-amino-1,3-selenazole-5-carboxylates

A series of methyl 2-amino-1,3-selenazole-5-carboxylates possessing a chiral pyrrolidin-2-yl, piperidin-2-yl, or piperidin-3-yl substituent at the C-4 atom of the heteroaromatic ring was designed and synthesized. In the first stage of the synthesis, the carboxylic acid functional group of the L-proline or related chiral heterocyclic amino acid was converted to the corresponding β-keto ester, which was then α-brominated with N-bromosuccinimide. The subsequent reaction of the α-brominated β-keto ester with selenourea afforded the target methyl 2-amino-1,3-selenazole-5-carboxylate. The structures of the novel heterocyclic compounds were confirmed by 1H, 13C, and 77Se NMR spectroscopy and HRMS.