(±)-6-azido-penicillanate (10). The synthesis involved a regiospecific chlorinolysis of the two sulphide bonds in (4) and in (7), followed by reductive cyclization of the resulting dichloro-compounds with tin(II) chloride. 3-p-Methoxybenzylthiovaline was used as starting material for the preparation of the key compounds (4) and (7), by a route involving the construction of the β-lactam ring on the nitrogen atom
将3-
叠氮基-1-(1-苄氧基羰基-2-对甲氧基苄
硫基-2-甲基丙基)-4-甲基
硫氮杂
环丁烷-2-酮(4)转化为苄基(±)-6-
叠氮基-6-表
青霉酸酯( 6),将其立体异构体(7)转化为苄基(±)-6-
叠氮基-5-表-
青霉酸酯(9)和苄基(±)-6-
叠氮基-
青霉酸酯(10)。合成涉及(4)和(7)中两个
硫键的区域特异性
氯化反应,然后用
氯化锡(II)对所得的二
氯化合物进行还原性环化。通过涉及在
氨基酸的氮原子上构建β-内酰胺环的途径,将3-对甲氧基苄基
硫代缬
氨酸用作制备关键化合物(4)和(7)的原料。