Photostimulated Reaction of 1-Haloadamantane and 9-Bromotriptycene with Nucleophiles. A Nucleophilic Substitution by SRN1 at the Bridgehead Position

Article abstract of DOI:10.1021/jo00198a007

1-Haloadamantanes and 9-bromotriptycene react under irradiation with diphenylphosphide and diphenylarsenide ions to give the substitution product in good yields. 1-Iodoadamantane (8) also reacts with disodium telluride and disodium selenide under irradiation to give di-1-adamantyl ditelluride and di-1-adamantyl diselenide, respectively. 9,10-Dibromotriptycene with diphenylphosphide gives a good yield of the disubstitution product.It seems that all these reactions occur by the S_RN1 mechanism.Substrate 8 reacts under irradiation with carbanionic nucleophiles and diethyl phosphite ion, but the products are adamantane and 1,1'-biadamantyl rather than substitution products.These nucleophiles transfer an electron to 8 to form radical anions which fragment to 1-adamantyl radicals.The radicals are reduced or dimerized.In contrast, amide ions do not react with 8.The ease of the halogen nucleofugality is I > Br > Cl, the same as in the aromatic system.