Fluorination of hydrocarbon chains influences their conformation.1For vicinal difluorination, the fluorine gauche effect is thought to have an important contribution to the stability of the possible conformation, which for 1,3-difluorination, dipole effects appear more important.2We have performed high level calculations to predict the relative free energies of the respective conformation, and the resulting conformer population in solvents of increasing dielectric constants.This presentation will describe an efficient synthesis of both 2,3-difluorobutane and 3,5-difluoroheptane diastereoisomers, and how the experimental NMR data were used to verify the computational data.  [1]-(a)-Kirsch, P. Modern Fluoroorganic Chemistry; Wiley-VCH: Weinheim, Germany, 2004. (b)-Chambers, R.D. Fluorine in Organic Chemistry, Blackwell, Oxford, 2004. (c)- O'Hagan, D. Chem.Soc.Rev. 2008 , 37, 308-319.[2]-(a)-Goodman, L.; Gu, H.; Pophristic, V. J. Phys. Chem. A, 2005 , 109, 1223-1229. (b)- Craig, N.C.; Chen, A.; Suh, K.H.; Klee, S.; Mellau, G.C.; Winnewisser, B.P.; Winnewisser, M.; J. Am. Chem. Soc. 1997 , 119, 4789-4790. (c)- Hunter, L.; Slawin, A.M.Z.; Kirsch, P.; O'Hagan, D. Angew. Chem. Int. Ed. 2007 , 46, 7887-7890. (d)- Wu, D.; Tian, A. J. Phys. Chem. A, 1998 , 102, 9901-9905.

Synthesis and conformational analysis of both 2,3-difluorobutane and 3,5-difluoroheptane diastereomers

248th National Meeting (2014)

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