Several β-hydroxy-α-halogeno-α-amino acid derivatives (3-5) were prepared from tert-butyl N-benzylideneglycinate (1) and α-haloketones or an α-haloaldehyde for utilization in the synthesis of 4, 5-dihydro-6H-1, 3-thiazine derivatives (7 and 12). An alternative thiazine synthesis starting from tert-butyl glycinate (13) was found to proceed stereoselectively, giving rise to 12a. The two thiazine derivatives 7 and 12a were converted into cephalosporin derivatives (10 and 17, respectively) by reaction with azidoacetyl chloride. The 7-azido-3-methylcephem derivative (17) was further led to 7-aminodeacetoxycephalosporanic acid (7-ADCA, 22).
几个β-羟基-α-卤代-
α-氨基酸衍
生物(3-5)是由叔丁基N-苄亚基甘
氨酸(1)与α-卤代酮或α-卤代醛反应制备的,用于合成4, 5-二氢-6H-1, 3-
噻嗪衍
生物(7和12)。从叔丁基甘
氨酸(13)出发的另一种
噻嗪合成发现以立体选择性进行,生成12a。两个
噻嗪衍
生物7和12a通过与
叠氮乙酰氯反应转化为
头孢菌素衍
生物(10和17)。7-
叠氮-3-甲基
头孢菌素衍
生物(17)进一步转化为7-
氨基去乙酰氧基
头孢菌素酸(
7-ADCA, 22)。