The intervention of side reactions further limits the scope of the thermal vinylcyclopropane rearrangement. Cyclo- propanes bearing syn vinyl and CH groups are subject to homo- [ 1,5]-sigmatropic hydrogen migration and rarely undergo satisfactory vinylcyclopropane rearrangment.3i4 Activation energies for homo [ 1,5] hydrogen shifts are typically 31-33 kcal/mol, significantly lower than the 48-52 kcal/mol required for normal thermal ...
