e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
Tetrahedron letters
The remarkable configurational stability of ortho, ortho′-tetrafluoro substituted biphenyls: 2, 2′, 4, 4′, 6, 6′-hexafluorobiphenyl-3, 3′-dicarboxylic acid as a model
Optically active 2, 2′, 4, 4′, 6, 6′-hexafluorobiphenyl-3, 3′-dicarboxylic acid was obtained through its brucine salt. The half-life time for racemization was determined at various temperatures and the torsional barrier for racemization was calculated to be 25.4 kcal/mol. These results prove, contrary to textbook knowledge, that ortho, ortho′-tetrafluoro substituted biphenyls are resolvable.
