Reaction of 2-chloro-1,3,2-benzodioxaphosphinin-4-one with 2-(arylmethylideneamino)phenols. Stereoselective formation of 10-aryl-3,4 : 8,9-dibenzo-5,7-dioxa-1-aza-6-phosphabicyclo[4.3.1]decane-2,6-diones

Cyclic mixed anhydrides derived from hydroxy carboxylic and phosphorous acids (2-R-1,3,2-benzodioxaphosphinin-4-ones or “salicyl phosphites”) contain a highly reactive macroergic POC(O) moiety and are convenient intermediate products for regioand stereoselective syntheses of various phosphorus-containing heterocyclic (including bridged polycyclic) systems which are difficult to obtain by other methods [1–4]. We previously reported on stereoselective synthesis of a 1,4,2-benzoxazaphosphepine derivative via intramolecular expansion of the six-membered ring in salicyl phosphite possessing a 2-(benzylideneamino)ethoxy group [5]. In the present communication we describe intramolecular cyclization processes in the system 2-chloro-1,3,2-benzodioxaphosphinin-4-one (I)–2-(arylmethylideneamino)phenol II in the absence of a base. Taking into account lower nucleophilicity of the nitrogen atom in aromatic Schiff bases and conformational rigidity of the aromatic ring, which should not favor intramolecular cyclization, we believed that the imine fragment in initially formed phosphite III (THF, 20°C) may act as a base. However, we failed to