Photochemical [2 + 2] cycloaddition reaction of carbonyl compounds with Danishefsky diene.

Danishefsky diene, trans-1-methoxy-3-trimethylsilyloxy-buta-1,3-diene, has been utilized in organic synthesis in thermal reactions for a long time. The purpose of this study is to investigate the photochemical reaction of ketones with Danishefsky diene. The [2 + 2] photocycloaddition products, oxetanes, were obtained in 65%-99% yield, along with the E to Z photochemical isomerisation of the diene. A mechanism involving intermediary triplet diradicals was proposed to rationalise the formation of the oxetanes.