Transformations of penicillins. Part V. Reactions of olefin and acetylene derivatives with the sulphenic acid intermediates from penicillin S-oxides

Abstract

Norbornadiene, dimethyl acetylenedicarboxylate, and vinyl ethers react with the sulphenic acids produced by heating penicillin S-oxides. Norbornadiene, diketen (4-methyleneoxetan-2-one), and dimethyl acetylenedicarboxylate react by addition, whereas vinyl ethers, such as dihydropyran, react by substitution with loss of water. Methanolysis of the vinyl ether products can be achieved with dilute methanolic hydrochloric acid. Removal of the nitrogen-containing substituent of the β-lactam ring from the vinyl ether products has been effected via the pyrazoline route. A novel substitution reaction occurs on heating the 3-hydroxypenam (22) with acrylaldehyde : methacrylaldehyde is displaced and the 4-hydroxycepham (25) is formed. Some reactions of this cepham are reported.