https://doi.org/10.1351/goldbook.O04359
A photochemical reaction of a $\ce{\upbeta\!,\upgamma\!\mbox{-}unsaturated ketone}$ to form a saturated $\ce{\upalpha\!\mbox{-}cyclopropyl ketone}$. The rearrangement formally amounts to a 1,2-acyl shift and 'bond formation' between the former $\ce{\upalpha\!}$ and $\ce{\upgamma\!\mbox{-}carbon atoms}$. 

See also: di-π-methane rearrangement