【文章名】The Proton Complex of a Diaza-macropentacycle: Structure, Slow Formation, and Chirality Induction by Ion Pairing with the Optically Active 1,1'-Binaphthyl-2,2'-diyl Phosphate Anion.
The Proton Complex of a Diaza-macropentacycle: Structure, Slow Formation, and Chirality Induction by Ion Pairing with the Optically Active 1,1'-Binaphthyl-2,2'-diyl Phosphate Anion.
[摘要]：The protonation of a sterically crowded [N2S6] macropentacycle (1) with and doubly (o+o+ [1?H]2+) protonated forms as kinetic products, the i+o form of [1譎]+ being the thermodn. product. i+o [1譎]+ is C3 helically chiral in the solid state and in soln. The barrier to racemization (DG\) of the [1譎]+ propeller is >71 kJ mol-1. The ammonium proton is encapsulated in the tetrahedral coordination sphere provided by the endo (i) nitrogen bridgehead atom and the three proximal thioether sulfurs, which makes [1譎]+ a proton complex. Use of the optically active acid (R)(-)- or (S)(+)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BNPH) in chloroform allowed us to induce a significant diastereomeric excess (24% de), which produced a detectable ICD. The de was decreased in acetone-d6 (10%), suggesting that the sense of chirality of [1譎]+ is controlled by ion-pair interactions. Detailed NMR studies allowed us to locate the chiral anion on the endo side of [1譎]+, in the cavity lined by endo t-Bu groups, and to establish that the rate of anion exchange in [1譎][(S,R)(?-BNP] was higher than the rate of propeller inversion of [1譎]+.
