Process for 3-iodomethyl cephalosporins

Claim 1

A process for preparing a 3-iodomethyl cephalosporin of the formula ##STR18## which comprises reacting in an aprotic solvent under substantially anhydrous conditions at a temperature between about 0° C. and about 35° C. a 3-alkanoyloxymethyl or 3-carbamoyloxymethyl cephalosporin of the formula ##STR19## with a trialkylsilyl iodide of the formula ##STR20## where in the above formulas R is hydrogen, C 1 -C 4 alkyl, cyanomethyl, halomethyl, or a group of formula ##STR21## wherein a and a' are independently hydrogen, carboxy, carboxymethyl, protected aminomethyl or halogen, C 1 -C 3 alkyl, or C 1 -C 3 alkoxy; Z is O or S; m and m' are 0 or 1; and when m is 1, m' is 1; or R is a heteroarylmethyl group of the formula R'--CH.sub.2 -- wherein R' is ##STR22## wherein b is H, C 1 -C 3 alkyl, or protected NH 2 ; and b' is H, or C 1 -C 3 alkyl; or R is an α-substituted arylmethyl or heteroarylmethyl group of the formula ##STR23## wherein R'' is thienyl, furyl, cyclohexyl, 1,4-cyclohexadienyl, phenyl, or substituted phenyl substituted by C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, or hydroxy, and, Q is protected-hydroxy, protected-amino, or protected-carboxy; or R is an α-oximino group of the formula ##STR24## wherein R''' is R'' as defined above or the group of the formula ##STR25## wherein b is H, C 1 -C 3 alkyl or protected NH 2 ; Y is hydrogen, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, benzyl, C 2 -C 4 alkanoyl, phenylsulfonyl, or C 1 -C 4 alkylsulfonyl; R o is hydrogen or methoxy; R 1 is C 1 -C 4 alkyl, 2,2,2-trichloroethyl, iodomethyl, diphenylmethyl, benzyl, substituted benzyl substituted by methyl, methoxy or nitro; or R 1 is a trialkylsilyl group of the formula ##STR26## wherein R 3 , R 3 ', and R 3 '' are independently C 1 -C 3 alkyl; or R 1 is sodium or potassium; R 1 ' has the same meanings as R 1 , provided that, when R 1 is sodium, potassium, diphenylmethyl, or p-methoxybenzyl, R 1 ' is ##STR27## R 2 is C 1 -C 4 alkanoyloxy or a carbamoyloxy group of the formula ##STR28## wherein R 2 ' and R 2 '' are independently hydrogen or C 1 -C 3 alkyl; and n is 0 or 1; with the limitation that when n is 1, the double bond represented by the dotted bonding lines is in the 3-position.