Stereochemical Features of the Physical and Chemical Interactions of Singlet Oxygen with Enecarbamates

Oxazolidinone-substituted enecarbamates represent a mechanistically rich system for the study of stereoelectronic, steric, and conformational effects on stereoselectivity and mode selectivity in 1O2 [2 + 2] and ene reactions. Photooxygenation of these enecarbamates with 1O2 leads to diastereomerically pure dioxetanes that decompose to yield an oxazolidinone carbaldehyde and one of the two enantiomers of methyldesoxybenzoin in enantiomeric excess. Stereoselectivity originates at the allylic stereocenter, a result supported by quenching studies, computational analysis, and deuterium solvent isotope effects.