REACTIONS OF 1,3-DIHALOADAMANTANES WITH DIPHENYLPHOSPHIDE IONS BY THE SRN1 MECHANISM. COMPETITION BETWEEN INTERMOLECULAR AND INTRAMOLECULAR ELECTRON TRANSFER REACTIONS

Article abstract of DOI:10.1002/poc.610071104

The reactivity of 1,3-dihaloadamantanes with diphenylphosphide ions (Ph₂P^-) in liquid ammonia was studied. 1,3-Dichloroadamantane (1a), 1-bromo-3-chloroadadmantane (1b) and 1,3-dibromoadamantane (1c) reacted with Ph₂P^- ions under photostimulation by the S_RN1 mechanism.Irradiation of 1c without Ph₂P^- ions gave no reaction (<5percent).Three products were found: 1,3-bis(diphenyphosphinyl)adamanatane (2), (3-X-1-adamantyl)diphenylphosphine (X = Cl, 3a; X = Br, 3b) and 1-adamantyldiphenylphosphine (4).Compounds 2 and 4 were formed by intramolecular electron transfer (ET) of the radical anion 3a^-. (3b^-.); whereas 3a (3b) were formed by intermolecular ET of this radical anion to the substrates.It was observed that the product distribution depends on the substrate and reaction conditions.