4794-05-2Relevant articles and documents
Synthesis and elaboration of all-cis-1,2,4,5-tetrafluoro-3- phenylcyclohexane: A polar cyclohexane motif
Durie, Alastair J.,Fujiwara, Tomoya,Cormanich, Rodrigo,Buehl, Michael,Slawin, Alexandra M. Z.,O'Hagan, David
, p. 6259 - 6263 (2014)
A stereocontrolled synthesis of all-cis-1,2,4,5- tetrafluoro-3- phenylcyclohexane is developed as the first functionalised example of this polar cyclohexane motif. The dipolar nature of the ring, arising due to two 1,3-diaxial C-F bonds, is revealed in the solid-state (X-ray) structure. The orthogonal conformation of the aryl and cyclohexyl rings in all-cis-1,2,4,5- tetrafluoro-3-phenylcyclohexane, and in an ortho-nitro derivative, result in intramolecular 1hJHF and 2hJCFNMR couplings relayed through hydrogen bonding. The aryl group of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane is elaborated in different ways to demonstrate the versatility of this compound for delivering the motif to a range of molecular building blocks. A stereocontrolled synthesis of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane is developed as the first functionalised example of this polar cyclohexane motif. The dipolar nature of the cyclohexane ring is explored and the aryl ring is elaborated in different ways to demonstrate its versatility as a molecular building block (see figure).
Substituent effects on the dehydration of arene hydrates in aqueous solution
O'Mahony, Michelle J.,More O'Ferrall, Rory A.,Boyd, Derek R.,Lam, Casey M.,O'Donoghue, Annmarie C.
supporting information, p. 989 - 996 (2014/01/06)
Rate constants have been determined by UV spectrophotometry at 25 °C for the acid-catalyzed dehydration of different types of monocyclic arene hydrates including those substituted at the 1-, 2- or 3-positions. General acid catalysis was not observed, and linear plots of pseudo-first-order rate constants for dehydration against hydronium concentration were obtained. A Hammett plot of the second-order rate constants for acid-catalyzed dehydration, kH (M-1s-1), of unsubstituted- (8a), 3-substituted (8b, 8c, 8d, 8e) and 1-substituted-benzene hydrates (14f and 14h) shows an excellent correlation with σ+ values and yields a large negative ρ-value of -6.5. The results are consistent with rate-determining formation of a benzenium ion in which direct mesomeric interaction with the substituent occurs, presumably permitted by the coplanar arrangement of the diene and carbocation centre in the intermediate. Data points for 2-substituted arene hydrates (13f, 13g, 13h, 13i) deviate negatively from the Hammett plot as direct mesomeric interaction with the substituent is not possible in the corresponding benzenium intermediates. Copyright 2013 John Wiley & Sons, Ltd. A large negative ρ-value of -6.5 is obtained in a correlation of rate constants for the acid-catalyzed dehydration of arene hydrates with σ+ values. Copyright
Preparation of 1-phenylcyclohexa-2,5-diene-1-carboxylates and their use in free-radical mediated syntheses
Baguley, Paul A.,Jackson, Leon V.,Walton, John C.
, p. 304 - 309 (2007/10/03)
Synthetic routes to pure 1-phenylcyclohexa-2,5-diene-1-carboxylic acid and derived esters were developed. Esters containing appropriately unsaturated side chains generated the corresponding alkenyl radicals and hence gave good yields of 5-exo ring closure products in organotin-free reactions. Extrusion of phenyl radicals from the intermediate cyclohexadienyl type radicals was not observed, and this alternative β-scission did not compete under any conditions. Yields from alkylations of olefins in analogous intermolecular processes were, however, poor. As a spin-off from the research, it was found that 1-phenylcyclohexa-2,5-diene-1-carboxylic acid (6) was a useful source of hydroxyformyl (formate) radicals in organic solvents.
