Chemistry of trans-Resveratrol with Singlet Oxygen: [2 + 2] Addition, [4 + 2] Addition, and Formation of the Phytoalexin Moracin M

Resveratrol (1) reacts with singlet oxygen by two major pathways: A [2+2] cycloaddition forming a transient dioxetane that cleaves into the corresponding aldehydes and a [4+2] cycloaddition forming an endoperoxide that, upon heating, undergoes a rearrangement to moracin M. The rate constant by which singlet oxygen is removed by 1 (k(T)) was determined by time-resolved infrared luminescence spectroscopy to be 1.5 × 10(6) M(-1) sec(-1) in CD(3)OD, smaller than previously reported values. Chemical reaction accounts for ca. 25% of k(T).