Isolation, reactivity and intramolecular trapping of phosphazide intermediates in the Staudinger reaction of tertiary phosphines with azides

The Staudinger reaction of the N-substituted o-azidobenzamide 1 with triphe nylphosphine or diphenylmethylphosphine allows the isolation of the interme diate phosphazides as crystalline solids, which have been characterized by spectroscopic methods. These compounds react in aza Wittig type fashion wit h isocyanates to give unexpectedly the corresponding 1,2,3-benzotriazinone derivative. Trapping of a Z-phosphazide by intramolecular aza Wittig reacti on is reported for the first time. (C) 2000 Elsevier Science Ltd. All right s reserved.