Nucleophilic substitution of halobicycloalkanes and halopolycycloalkanes by electron transfer reactions

The 2-iodoadamantane reacted with carbanions in DMSO to form the substituti on products in good yield by the S(RN)1 mechanism. The reaction of the subs trates 1-halotricyclo[4.1.0.0(2,7)] heptanes (19) with Ph2P- ions was found to depend on the halogens. The fact that the substitution product isomeriz es under the experimental conditions makes 19 unsuitable for S(RN)1 reactio ns. The 1-bromoquadricyclane reacted by the S(RN)1 mechanism with Ph2P- ions to give the substitution product in high yields. The reaction of 1,3-dihalobi cyclo[1.1.1]pentanes with Ph2P- ions and carbanions afforded propellane.