Towards novel difluorinated sugar mimetics; syntheses and conformational analyses of highly-functionalised difluorinated cyclooctenones.
Highly-functionalised difluorinated cyclooctenones were synthesised from trifluoroethanol using either metallated difluoroenol acetal or carbamate chemistry, followed by a [2,3]-Wittig rearrangement or aldol reaction. Efficient RCM reactions afforded the title compounds which showed rather restricted fluxional behaviour by VT (19)F NMR. Topological characterisation by molecular modelling and NOESY/ROESY experiments offered a number of challenges, but allowed the identification of two favoured boat-chair conformers which interconverted by pseudorotation with relatively large activation barriers.
Griffith
Gerry A
GA
Department of Chemistry, University of Leicester, University Road, Leicester, UK LE1 7RH.
Percy
Jonathan M
JM
Pintat
Stéphane
S
Smith
Clive A
CA
Spencer
Neil
N
Uneyama
Emi
E
D002241:Carbohydrates / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D018716:Molecular Mimicry; D016339:Spectrometry, Mass, Fast Atom Bombardment
D002241:Carbohydrates; D006841:Hydrocarbons, Aromatic; D005461:Fluorine