| 摘要 |
<p>1461323 Silylated x-aminoacyl-3-halo-cephalosporins ELI LILLY & CO 22 Feb 1974 [23 Feb 1973] 8097/74 Heading C3P [Also in Division C2] Novel compounds of the Formula I wherein R is phenyl,mono- or dihydroxy phenyl, mono or dihalophenyl, mono or dimethylphenyl, mono- or dimethoxyphenyl, 2- or 3-thienyl or 2- furyl; R 1 is hydrogen, benzyl, p-methoxybenzyl, p-nitrobenzyl, diphenylmethyl, 2,2,2- trichloroethyl, trimethylsilyl or t-butyl; R 2 is hydrogen or an amino-protecting group; X is fluoro, chloro or bromo and pharmaceutically acceptable salts thereof when R 1 or R 2 is hydrogen, may be prepared by (i) halogenating and acylating in either order a compound of the Formula II wherein R 3 is a carboxylic acid protecting ester forming group optionally followed by removal of the carboxylic acid protecting ester forming group and or the amino-protecting group or (ii) fluorinating a 3-alkyl or aryl sulphonate of a compound II (R 1 #H) having a protected amino group, followed by acylation. In the above process (i) when halogenation is effected as the first step a protecting acyl group may be introduced on the 7-amino group prior to halogenation and thereafter removed.</p> |
