Ampicillin prepn. from natural penicillins - by conversion into 9-anthrylmethyl ester of ampicillins and hydrolysis of the ester

摘要

Prepn. of ampicillin is new by converting the 9-anthryl methyl ester of a natural penicillin e.g. benzylpenicillin, into the 9-anthrylmethyl ester of ampicillin. This ester is hydrolysed with an acid (trichloroacetic acid) or a base (alkylmercaptan Na salt). The 9-anthrylmethyl esters of benzyl penicillin and ampicillin are new. The use of 6-APA is avoided. The ester group protects the beta-lactam ring and is readily removed. Penicillins G or V are converted into their 9-anthrylmethyl esters, then into the iminohalides and iminoethers. The latter react with reactive derivs of phenylglycine to give the 9-anthrylmethyl ester of ampicillin. Hydrolysis gives ampicillin.