Chelating P2-Bis-phosphazenes with a (R,R)-1,2-Diaminocyclohexane Skeleton: Two New Chiral Superbases.
The linkage of two P2 -phosphazenyl groups through a C2 -symmetric (R,R)-1,2-diaminocyclohexane (DACH) backbone yielded the new chiral superbases DACH-P2 NMe2 and DACH-P2 Pyr (Pyr=pyrrolidinyl). These bases were prepared by a Kirsanov reaction and studied with respect to their spectroscopic and structural characteristics. Theoretical calculations concerning their basicity properties revealed remarkable pKBH+ values of 38.1 and 39.9 on the acetonitrile scale; this makes them the strongest nonionic chiral superbases known to date.
['Kögel|Julius F|JF|', 'Kovačević|Borislav|B|', 'Ullrich|Sebastian|S|', 'Xie|Xiulan|X|', 'Sundermeyer|Jörg|J|']
chirality superbases basicity density functional calculations phosphazenes