The effect of ligands, solvent and temperature on the reactions of allyltin(IV) compounds with singlet oxygen

Article abstract of DOI:10.1016/0022-328X(92)83265-J

The reaction of singlet oxygen with a variety of allyltin compounds CH2=CHCH2SnR3 (R3 = Me3, Bu3, allyl3, (cyclo-C6H11)3, Ph3, allylBu2, Bu2Cl, Bu2OAc, allylCl2, allylCl2bipy) has been investigated, and the allylperoxytin compounds, 3-stannylallyl hydroperoxides, and 4-stannyl-1,2-dioxolanes which result from M-ene, H-ene and cycloaddition processes, respectively, have been identified by NMR spectroscopy.As the tin centre becomes more electropositive, as indicated by the 13C NMR shift of the allylic CH2 group, the proportion of the M-ene reaction increases, and when δCH2 is above about 23.7, the allylperoxytin compound is the only product.An exception to this rule is tetraallyltin, δCH2 16.13, which similarly shows only the M-ene reaction.This is tentatively ascribed to the special effect of hyperconjugation between the C-Sn ?-bond and the remaining ?-systems.A polar solvent favours the M-ene reaction.The cycloaddition reaction is favoured by low temperature, and at -70 deg C in a non-polar solvent it may become the major route.Diallylmercury and allylmercury chloride react with singlet oxygen to show only the M-ene reaction, but also undergo extensive photosensitized decomposition.With 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), allylmercury chloride shows only the M-ene reaction.