Reactions of N-chloro β-lactams

N-Chloro β-lactam 4 was prepared to explore its potential for a methoxy transfer to the C3 position of the β-lactam. Methoxy addition to C3 of β-lactam 4 with concomitant loss of chloride to give α-methoxy β-lactam 5 occurred under mild alkaline conditions but was accompanied by methanolysis of the β-lactam ring as the major reaction pathway. Reaction of 4 with AgNO3 promoted methoxy addition to C4 of the β-lactam followed by subsequent reactions.