Radical and radical-like reactions of (1.1.1);propellane.

Abstract

(1.1.1) Propopellane, I, is the ultimate propellane in terms of its small size and the inversion of the tetrahedral geometry about its bridgehead carbons. As such I is reactive towards radicals and carbenes. We have studied the kinetics and mechanisms of reaction of various carbon and heteroatom centered free radicals with I by nanosecond flash photolysis and product studies techniques.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The addition of diphenylcarbene (DPC) and phenylchlorocarbene (PCC) to I have also been investigated. Addition of DPC proceeds via a 1,4-biradical intermediate, II, whereas with PCC it appears that the final product, III, is formed directly upon reaction. The implications of the apparent concerted addition of the singlet carbene to I are discussed.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The role of I as a quencher of electronic excited states is also reported.