Concerning the ring-opening of substituted cyclopropyl radicals

Abstract

The stereochemistry of the conversion of cyclopropyl radicals to allyl radicals is discussed. The rearrangement of 1,5-dimethyl-6-bicyclo[3.1.0]hexyl radicals to 1,3-dimethylcyclohex-2-enyl radicals affords a new example of disrotatory opening, and, taken in conjunction with the apparent failure of 2,2,3,3-tetramethylcyclopropyl radicals to rearrange under comparable conditions, is considered to exclude the possibility of any significant preference for conrotatory opening, in contrast to early predictions. An improved synthesis of trans-cyclo-octane is also reported.