Reactions of 1,3‐dihaloadamantanes with diphenylphosphide ions by the SRN1 mechanism. Competition between intermolecular and intramolecular electron transfer reactions

Abstract

AbstractThe reactivity of 1,3‐dihaloadamantanes with diphenylphosphide ions (Ph2P−) in liquid ammonia was studied. 1,3‐Dichloroadamantane (1a), 1‐bromo‐3‐chloroadamantane (1b) and 1,3‐dibromoadamantane (1c) reacted with Ph2P− ions under photostimulation by the SRN1 mechanism. Irradiation of 1c without Ph2P− ions gave no reaction (<5%). Three products were found: 1,3‐bis(diphenyphosphinyl)adamantane (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.