Janus Face All-cis1,2,4,5-tetrakis(trifluoromethyl)- and All-cis1,2,3,4,5,6-hexakis(trifluoromethyl)- Cyclohexanes

• Published in: Angewandte Chemie International Edition Vol. 59; no. 45; pp. 19905 - 19909
• Main Authors: Yu, Cihang, Kuett, Agnes, Roeschenthaler, Gerd-Volker, Lebl, Tomas, Cordes, David B., Slawin, Alexandra M. Z., Buehl, Michael, O'Hagan, David
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 02.11.2020
• Subjects: Chemistry; Chemistry, Multidisciplinary; Physical Sciences; Science & Technology; HEXAFLUOROCYCLOHEXANE; HYDROGENATION; BENZENE; ANION; trifluoromethyl groups; aryl hydrogenation; cyclohexanes; Janus face; ALL-CIS 1,2,3,4,5,6-HEXAFLUOROCYCLOHEXANE; triaxial orientations
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202008662

We report the synthesis of all-cis1,2,4,5-tetrakis (trifluoromethyl)- and all-cis1,2,3,4,5,6-hexakis (trifluoromethyl)- cyclohexanes by direct hydrogenation of precursor tetrakis- or hexakis- (trifluoromethyl)benzenes. The resultant cyclohexanes have a stereochemistry such that all the CF(3)groups are on the same face of the cyclohexyl ring. All-cis1,2,3,4,5,6-hexakis(trifluoromethyl)cyclohexane is the most sterically demanding of the all-cishexakis substituted cyclohexanes prepared to date, with a barrier (Delta G) to ring inversion calculated at 27 kcal mol(-1). The X-ray structure of all-cis1,2,3,4,5,6-hexakis(trifluoromethyl)cyclohexane displays a flattened chair conformation and the electrostatic profile of this compound reveals a large diffuse negative density on the fluorine face and a focused positive density on the hydrogen face. The electropositive hydrogen face can co-ordinate chloride (K approximate to 10(3)) and to a lesser extent fluoride and iodide ions. Dehydrofluorination promoted decomposition occurs with fluoride ion acting as a base.