Jennings, WB,Farrell, BA,Malone, JF;

2006

March

The Journal of Organic Chemistry

Stereodynamics and edge-to-face CH-pi aromatic interactions in O-phenethyl-substituted biaryls

Validated

()

CRYSTAL-STRUCTURE SUPRAMOLECULAR STRUCTURES METAL-COMPLEXES CONFORMATION DERIVATIVES LIGANDS BINDING IMINES

71

2277

2282

[GRAPHICS]As part of a search for systems that exhibit intramolecular aromatic edge-to-face interactions, a series of four biaryl compounds containing a phenethyl side chain were prepared. These compounds exist as a slowly interconverting mixture of two atropisomers due to steric hindrance to rotation about the biaryl bond. The more thermodynamically stable isomer exhibits an abnormal shielding of an ortho-proton in solution indicative of an edge-to-face CH-pi interaction with the terminal phenyl ring on the side chain. This tilted-T type of geometry was observed in the X-ray crystal structure of one of the compounds. The edge-to-face conformation in solution is estimated by variable temperature NMR studies to be energetically favored by ca. 1.6 kcal mol(-1) but entropically disfavored by ca. 5.0 cal K-1 mol(-1).

DOI 10.1021/jo0520902