C-13 NMR AND H-1-NMR STUDY OF SUBSTITUTED TRICYCLIC [2+2] PHOTOADDUCTS

The C-13 NMR chemical shifts for a series of substituted tricyclo[5.3. 0.0(2,6)]decan-3-ones and tricyclo[5.4.0.0(2,6)]undecan-8-ones derived from [2 + 2] photoaddition reactions are assigned and the influence o f various substituents is discussed. In general, it was found that sub stituent shifts are less for cyclobutane carbons than carbons in five- or six-membered rings. The H-1 NMR spectra for many of these adducts are also reported. These detailed assignments should assist organic ph otochemists in elucidating structures of new photoadducts.