ChemInform Abstract: Formation of 2,3-Dihydro-1,3,2-benzoxazaphospholes by Cheletropic Reaction of o-Quinone Monoimines with Triphenylphosphane. Crystal and Molecular Structures of 2,3-Dihydro-2,2,2-triphenylphenanthro(9,10-d)-1,3,2λ5-oxazaphosphole and 5,7-Di-tert.-butyl-2,3-dihydro-2,2,2-triphenyl-1,3,2λ5-benzoxazaphosphol# e.

ChemInform Abstract

In the presence of ammonia (III) the o-benzoquinones (I) undergo cycloaddition with PPh₃ (II) to give the title compounds (IV). (IVb) is also obtained by cycloaddition of 9,10-phenanthrenequinone monoimine (V) with PPh₃ (II). In solution the di-tert.-butylbenzoxazaphosphole (IVa) forms a solvent-dependent tautomeric equilibrium with the iminophosphorane (VI), while (IVb) has a cyclic structure. The structures of (IVa) (space group P2₁/n, Z=4) and (IVb) (P2₁/c, Z=4) are determined by X-ray analysis.