Chiral configurations of spirane-bridged cyclotriphosphazenes

Abstract

The stereogenic properties of carbocyclic spiranes with two interlocking rings are well-established. Although some cyclophosphazene analogues of dispiranes have been reported, the molecules did not have any centres of chirality because they were symmetrically substituted. Linear tetra-spiranes, in which the two inner rings are carbocyclic and symmetrical and the two outer rings are unsymmetrically-substituted cyclotriphosphazenes, are expected to give rise to chiral molecules. We now report on the synthesis and ste-reogenic properties of the three structural types of pentaer-ythritol-bridged disubstituted cyclophosphazenes, which all have centres of chirality. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).