STEREOSELECTIVE FORMATION OF 3-CHLORO-2,4,5-TRIPHENYL-3,4-DIHYDRO-2H-1,2,3-DIAZAPHOSPHOL-3-OXIDE VIA AN “ARBUZOV-LIKE” REACTION AND ITS DECOMPOSITION TO INDOLE

Abstract

The reaction of phenylazostilbene (1) and methoxydichlorophosphine gives the formation of the title compound via an intramolecular “Arbuzov-like” reaction. The trans isomer is easily isolated in a pure form by simple filtration of the reaction mixture. This compound in dichloromethane solution at room temperature converts into 2,3-diphenylindole. In addition, the reaction of (1) with phosphorus trichloride gives a cycloadduct which easily decomposes to the same indole. These results are a further convincing evidence that diazaphosphole system can be an intermediate in the synthesis of aza-heterocycles.