3'-bromo-acetoxy person to replacement price Palo Castello arithmetic method of producing seed width derivatives

摘要

The title compds. of formula (B) were prepd. by protecting the 4- carboxy gp. of a 3'-unsubstd. cephalosporanic acid sulfoxide by silylating the mixt. in an inert, anhydrous, organic solvent with a silylating agent contg. at least 1 N-bound silyl gp. (A). After neutralizing any base generated or left behind by the silyl donor, the silylated compd. was brominated in situ. The silylating agent is pref., e.g. hexamethyl disilazane, N,N'-bis(trimethylsilyl) urea, 1,3-bis(trimethylsilyl) hydrotoin, etc. Bromination is pref. effected using N-bromosuccinamide, N-bromocaprolactam, Nbromoacetamide, etc. Neutralizing acids are pref. methanesulfonic acid, formic acid, etc. R1 is acylamino; R',R" and R"' are independently C1-6 alkyl or aryl.