Modulating the propeller-like shape of a tripodal C(CH2PPh2)3 fragment by the size of the substituent at the pivotal carbon atom in macrobicyclic tri-λ5-phosphazenes
The chiral macrobicyclic tri-λ5-phosphazenes formed by tripod–tripod coupling of tris(3-azidobenzyl)amines and 1,1,1-tris[(diphenylphosphino)methyl]methanes present helical topologies as a result of combining two propeller-shaped tripodal fragments with the same sense of twist. The introduction of a series of Rpiv substituents of increasing size at the pivotal carbon of the lower tert-butane fragment
Macrobicyclic triphosphazides and tri-λ5-phosphazenes derived from PhC(CH2PPh2)3. Two propeller-shaped diastereoisomers in the crystals
作者:Mateo Alajarín、Carmen López-Leonardo、José Berná、Jonathan W. Steed
DOI:10.1016/j.tet.2006.12.027
日期:2007.2
Newmacrobicyclic cage-compounds composed of two tripodal, propeller-shaped fragments linked by phosphazide and phosphazene units have been synthesized by reaction of PhC(CH2PPh2)3 with tris(m-azidobenzyl)amines. Two diastereoisomers of one of these cages have been characterized in the solid state by X-ray crystallography, one presenting two propellers with the same sense of twist P∗,P∗ whereas in
The helical chirality of a conformationally stable macrobicyclic tri-lambda(5)-phosphazene is propagated through to its C-3 symmetry axis and causes a measurable stereoinduction in the formation process of a second macrobicyclic tri-lambda(5)-phosphazene unit connected to the former one by a p-phenylene linker.