Practical Preparation of (<i>Z</i>)-2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetic Acid: A Side-Chain of the Fourth Generation of Cephem Antibiotics
作者:Kuniaki Tatsuta、Shozo Miura、Hiroki Gunji、Tetsuro Tamai、Ryonosuke Yoshida、Takashi Inagaki、Yasuyuki Kurita
DOI:10.1246/bcsj.67.1701
日期:1994.6
A Z-isomer (4) of 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetic acid, which is the common acyl moiety of clinically useful cephem antibiotics, has been prepared from the aminoisoxazoles through the skeletal rearrangement in several routes. Reaction of 3-amino-5-methoxyisoxazole (7) with alkoxycarbonyl isothiocyanates gave methyl 2-(5-alkoxycarbonylamino-1,2,4-thiadiazol-3-yl)acetates (8), which were converted into the target compound 4 through the reaction of the corresponding keto ester with O-methylhydroxylamime. Compound 4 was prepared similarly from 3-aminoisoxazole (10). Also, O-methylation of 2-hydroxyimino-2-(5-methoxycarbonylamino-1,2,4-thiazol-3-yl)acetate (15) with methyl iodide or dimethyl sulfate in the presence of barium oxide and barium hydroxide octahydrate was found to afford exclusively the desired Z-isomer (14a) of methyl 2-(5-methoxycarbonylamino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetate, which was led to 4.
2-(5-氨基-1,2,4-噻二唑-3-基)-2-(甲氧亚氨基)乙酸的一种Z型异构体(4),是临床上有用的头孢菌素抗生素的共同酰基部分,已通过几个途径的骨架重排从氨基异噁唑制备。3-氨基-5-甲氧基异噁唑(7)与烷氧羰基异硫氰酸酯反应得到甲基2-(5-烷氧羰基氨基-1,2,4-噻二唑-3-基)乙酸酯(8),通过相应的酮酯与O-甲基羟胺的反应转化为目标化合物4。化合物4同样从3-氨基异噁唑(10)制备。此外,2-羟基亚氨基-2-(5-甲氧羰基氨基-1,2,4-噻唑-3-基)乙酸酯(15)在氧化钡和八水合氢氧化钡存在下与甲基碘或硫酸二甲酯的O-甲基化反应仅得到所需的Z型异构体(14a),即甲基2-(5-甲氧羰基氨基-1,2,4-噻二唑-3-yl)-2-(甲氧亚氨基)乙酸酯,进而制得4。