A NEW APPROACH TO THE SYNTHESIS OF DIAZOMETHYLENEPHOSPHORANES (GREATER-THAN-P=C=N-2)

Addition of tetrachloro-ortho-benzoquinone to [bis(diisopropylamino) p hosphino] (trimethylsilyl) diazomethane 1 leads to )phosphinyl]diazome thyl}-3,4,5,6-tetrachlorophenol 4 (30% yield) and the seven-membered h eterocycle 5 (5% yield). Both compounds have been characterized by sin gle crystal X-ray diffraction studies. The formation of 4 is rationali zed by the transient formation of a P-aryloxy diazomethylenephosphoran e 3, which undergoes a Chapman-type rearrangement.