New observations on the cyclisation of compounds containing the P–N–P skeleton by primary amines; an extension to diphosphinoyl-methanes

Abstract

Dichlorophosphino(dichlorophosphinoyl)methylamine, Cl₂P·NMe·P(O)Cl₂, reacts with 3 mol equiv of t-butyl-amine to give the cyclodiphosphazane Cl[graphic omitted]Bu^t. By contrast, (Bu^tHN)[graphic omitted]Bu^t is the only product isolated from the analogous reaction with Cl₂P·NMe·P(S)Cl₂. Similar reactions of Cl₂(O)P·CH₂·P(O)Cl₂ with NH₂Bu^t and NH₂Prⁱ give a new class of ring compound, Cl(O)[graphic omitted]R (R = Prⁱ or Bu^t)(1,2,4-azadiphosphetans), but no cyclic products have been identified from analogous reactions with Cl₂(O)P· CH₂·CH₂·P(O)Cl₂. Attempted cyclisation of (Me₂N)Cl(O)P-CH₂-P(O)Cl(NMe₂) by NH₂Bu^t gives an acyclic product. (Bu^tHN)(Me₂N)(O)P·CH₂·P(O)(NMe₂)(NHBu^t), rather than (Me₂N)(O)[graphic omitted]Bu^t. The latter cyclic derivative, obtained by heating (Me₂N)₂(O)P·CH₂·P(O)(NMe₂)(NHBu^t), is resistant to ring opening by NHMe₂, whereas ring opening occurred in the attempted dimethylaminolysis of Cl(O)[graphic omitted]Bu^t. Attempts to prepare pure samples of Cl₂P·CH₂·PCl₂, as a substrate for cyclisation reactions, from the reaction of PCl₃ with Ph₂P·CH₂·PPh₂, have been unsuccessful, and some of the products of these reactions are described.