3,6-二甲氧基-2,5-二氢吡嗪-2-羧酸乙酯的合成

Synthesis of Ethyl 3,6-Dimethoxy-2,5-dihydropyrazine-2-carboxylate

用苄氧羰基氨基乙酸在N-甲基吗啉的催化下与氯甲酸异丁酯反应后,无需分离直接与氨基丙二酸二乙酯盐酸盐反应得到(2-苄氧羰基氨基乙酰胺基)丙二酸二乙酯,经Pd/C催化氢解、环合后在二氯甲烷中与Me3OBF4反应制得a-取代丝氨酸的合成中间体3,6-二甲氧基-2,5-二氢吡嗪-2-羧酸乙酯,总收率35.1%。

Ethyl 3,6-dimethoxy-2,5- dihydropyrazine-2-carboxylate, a key intermediate for diastereoselective andenantioselective syntheses of the chiral a-substituted serine, was synthesized from benzyloxycarbonylaminoacetic acid byreaction with i-BuOCOCl in the presence of N-methylmorpholine and then condensation with diethyl aminomalonate hydro-chloride give diethyl (2-benzyloxycarbonylaminoacetamido)malonate, which subsequently subjected to catalytichydrogenolysis, cyclization and then etherification with an overall yield of 35.1%.