Synthesis of Adamantane Derivatives by Bridgehead Radical Addition to Electron-Deficient Unsaturated Bonds

Article abstract of DOI:10.1021/jo00241a030

Introduction of β-functional alkyl and alkenyl groups to the adamantane bridgehead was carried out by radical-mediated reactions of 1-adamantyl bromide and iodide (1a and 1b) with alkenes and alkynes containing electron-withdrawing groups in the presence of tributyltin hydride and AIBN.As expected, the reactions of polybromoadamantanes 7-9 with acrylonitrile gave 1,3-, 1,3,5-, and 1,3,5,7-polycyanoethyl-substituted derivatives; yield decreased with increasing substitution.Notably, by this method, α-hydroxy ester and monohydrazine derivatives were obtained by using the silyl enol ether of pyruvate ester and diethyl azodicarboxylate as a radical acceptor, respectively.The course of reaction is rationalized as a radical chain cycle, and the reactivity pattern of alkenes indicates that the radical addition process is governed by a SOMO-LUMO interaction of a radical and an alkene.A recently reported reaction of an alkyl halide with a zinc-copper couple in aqueous ethanol is complementary to the above tin method.Thus, 1b reacted with α,β-unsaturated carbonyl compounds in the presence of a zinc-copper couple; in some cases the yield was improved greatly.