Treatment of 7β-sulfenamidocephalosporins 7 with an oxidizing agent such as active manganese dioxide gave the sulfenimines 8, which were easily methoxylated to the 7α-methoxy-sulfenamides 9 with lithium methoxide. The 7α-methoxy-sulfenamidocephalosporins 9 were converted to the free amine 10 by reaction with sodium iodide. Acylation of 10 afforded the cephamycin derivative 11. This method was also successfully applied to the penicillin series, leading to the sulfenimine 13, which was methoxylated to furnish the desired 6α-methoxy-penicillin 14 together with the ring-opened product 15.
将7β-磺酰胺
头孢菌素7与
二氧化锰等氧化剂反应得到亚砜
亚胺8,然后用
甲醇锂容易甲氧基化得到7α-甲氧基-磺酰胺9。7α-甲氧基-磺酰胺
头孢菌素9与
碘化钠反应转化为游离胺10。将10酰化得到头霉素衍
生物11。这种方法也成功应用于
青霉素系列,得到亚砜
亚胺13,经甲氧基化得到目标产物6α-甲氧基-
青霉素14和开环产物15。