CEPHALOSPORINS

1487369 Silylated cephalosporins E R SQUIBB & SONS Inc 9 Dec 1974 [28 Dec 1973 10 May 1974] 53116/74 Heading C3S [Also in Division C2] Novel compounds I (R 1 is H, 1-8C alkyl, phenyl or phenyl-1-8C alkyl-optionally substituted by halo, 1-8C alkyl or alkoxy, OH or COOH- or R 1 is 5-6- membered heterocyclyl optionally substituted by halo, 1-8C alkyl or alkoxy or phenyl; R 2 is 1-8C alkyl; R 3 is tri(1-8C alkyl)silyl and R 4 is H, acetoxy, a quaternary ammonium radical, 1-8C alkylthio, heterocyclylthio or a nitrogenlinked radical of an amine) are prepared by reaction of a compound II or an acylating derivative thereof with a compound III