A convenient synthesis of 2,7-dioxa-5,10-diaza-3λ5,8λ5-diphospha-1,6(1,4)-dibenzenacyclodecaphanes

Abstract

SHORT COMMUNICATIONSPhosphorus-containing macrocyclic compounds attract interest from the viewpoint of supramolecular chemistry as model structures for studying molecular recognition and complexation processes. Therefore, much attention is given to the development of methods of synthesis of such compounds [1][2][3][4][5][6][7].We previously showed for the first time [8] that p-(benzylideneamino)phenol in the absence of other bases reacts with dialkyl phosphorochloridites in chloroform to give phosphorus-containing [4.4]paracyclophane analogs. The present communication reports on the results of analogous reactions with substituted iminophenols both in the absence (Scheme 1) and in the presence of other base (Scheme 2).The reaction of diethyl phosphorochloridite with 4-(arylmethylideneamino)phenols Ia and Ib at a ratio of 1 : 1 (20°C, CHCl 3 ) was carried out in an argon atmosphere (Scheme 1). If no other base was added, the reaction was accompanied by separation of some solid from the reaction mixture. Analogous pattern was observed previously in the reaction of 4-(benzylideneamino)phenol with dialkoxy(chloro)phosphines [8]. On the basis of the 1 H NMR data and elemental analysis, the precipitate was identified as iminophenol hydrochloride I′a or I′b. Thus in the absence of other base, both phosphites IIa and IIb and initial iminophenols Ia and Ib act as acceptors of hydrogen chloride liberated during the process. The most probable way of formation of [4.4]paracyclophanes Va and Vb involves initial generation from diethyl phosphorochloridite and iminophenol I of iminium salts III which undergo cyclization to macrocyclic quasiphosAr = 4-MeOC 6 H 4 (a), 4-BrC 6 H 4 (b).