Photochemical reaction of NN-dialkylmethacrylamides. An olefin analogue of the type II photoelimination of ketones
Both photocyclization of NN-bis(benzyl)methacrylamide (1a) to a β-lactam (2a) and photodealkylation of NN-diisopropylmethacrylamide (1b) to N-isopropylisobutyramide (3b) were found to proceed via dimethylketen and the corresponding imine (4). The reactions provide the first example of type II reaction of aliphatic olefins. The behaviour of the 1,4-biradical intermediate involved in the reaction is discussed in relation to that of similar biradicals.