The reaction of N,N,O-tris(trimethylsily1)-o-aminophenol with two equivalents of phosphinic chloride yielded dimeric 2,2-disubstituted 1 ,3,2h5-benzoxazaphospholes and trimethylsilyl phosphinate. The chlorides having the bulk substituents (0-chlorophenyl or tert-butyl) at phosphorus or containing P-N and P-0 bonds (instead o f a P-C bond) either didn't react at all or reacted to retain the phosphoryl group. Being stable in solution at 20"C, the individual diastereoisomers of dimeric I ,3,2-benzoxazaphospholes were converted upon warming to an equilibrium mixture of isomers. When reacted with another dimer each gave a mixed dimeric compound having two different phosphorus atoms in the molecule.
Dimeric 2,2-dialkyl(or diaryl)-l,3,2-benzoxazaphospholes (1) were synthesized by different routes; for example, by reaction of o-azidophenol with chlorophosphines [2], by dealkoxylation of 2-alkoxy-2,3-dihydro-2,2-diphenyl-1,3,2-benzoxazaphosphole (2) [3], or by reaction of o-aminophenol with trichloro-or trifluorophosphoranes followed by treatment with base [2, 4, 51. The reaction of 2alkyl-2,3-dihydro-1,3,2-benzoxazaphosphole with acrylonitrile [6] or bis(diethy1amino)methane [7] could serve as a more specific method for preparing the dimers 1 containing P-C bonds.