Unexpected oxadi-pi-methane rearrangement of beta,gamma-unsaturated aldehydes

The efficient oxadi-pi-methane (OPDM) rearrangements in the triplet-sensitized irradiation of twelve cyclic and acyclic aldehydes are described. The results showed that the OPDM rearrangement of beta,gamma-unsaturated aldehydes occurred when the triplet energy from the sensitizer is transferred to the alkene moiety generating a T1 (3pi,pi*) excited state.