Facile and stereospecific synthesis of cis-3-(N'-arylureido)-2,3- dihydro-2-phenyl-1,2-benzoxaphosphole 2-oxides

A simple method for the preparation of cis-3-(N'-arylureido)-2,3- dihydro-2-phenyl-1,2-benzoxaphosphole 2-oxides 7 in moderate to high yields consists in the three-component reaction of phenyldichlorophosphine with salicylaldehyde and arylureas in anhydrous benzene. The stereochemistry and the possible reaction mechanism of the cyclizations are also discussed. The results presented in this paper provide a new general and efficient approach to the novel organophosphorus heterocycles with the 3-substituted 2,3- dihydro-1,2-benzoxaphosphole 2-oxide ring system.