Chelating P2‐Bis‐phosphazenes with a (R, R)‐1, 2‐Diaminocyclohexane Skeleton: Two New Chiral Superbases. Issue 11 (27th January 2017)

• Record Type: Journal Article
• Authors: Kögel, Julius F.; Kovačević, Borislav; Ullrich, Sebastian; Xie, Xiulan; Sundermeyer, Jörg
• Is Part Of: Chemistry. Volume 23:Issue 11(2017)
• Page Start: 2591
• Page End: 2598
• Publication Date: 2017-01-27
• Subjects: basicity -- chirality -- density functional calculations -- phosphazenes -- superbases; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201604522
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The linkage of two P2 ‐phosphazenyl groups through a C 2 ‐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 p K BH + values of 38.1 and 39.9 on the acetonitrile scale; this makes them the strongest nonionic chiral superbases known to date. Abstract : Back to basic : The two strongest nonionic superbases known were designed by connecting two diphosphazenes through a cyclohexane backbone. A conformational change after protonation leads to the formation of an intramolecular hydrogen bond and a slightly enhanced basicity (see figure).