Calix[6]arene threading with weakly interacting tertiary ammonium axles: generation of chiral pseudorotaxane architectures

Org Lett. 2015 Feb 20;17(4):1006-9. doi: 10.1021/acs.orglett.5b00115. Epub 2015 Feb 3.

Abstract

The TFPB "superweak anion" effectively induces the threading of a scarcely preorganized calix[6]arene (1) with weakly interacting tertiary ammonium axles (2(+)-3(+)). The pseudorotaxanes (4(+)-5(+)) thus formed show an unexpected chirality due to an unprecedented formation of a threading-induced stereogenic ammonium center.