R. Banks, M. K. Besheesh, R. Górski
Jul 4, 1999
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0
Influential Citations
12
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Journal
Journal of Fluorine Chemistry
Abstract
Abstract Treatment of 1,3,5-trimethoxybenzene with one molar equivalence of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA-BF4) under mild conditions (−40 to +20°C) in acetonitrile gave mainly 2-fluoro-1,3,5-trimethoxybenzene (62% yield; all product yields quoted refer to isolated pure materials, unless otherwise stated) and some 4,4-difluoro-3,5-dimethoxycyclohexa-2,5-dien-1-one (13% yield), the structural parameters of which were determined by X-ray crystallography. Evidence that the minor product arose via fluorodemethylation of the 2-fluoro-1,3,5-trimethoxybenzene formed first was obtained in a separate experiment involving this fluoroaromatic compound and F-TEDA-BF4 as the sole reactants. Treatment of 1,3,5-trimethoxybenzene with a two molar equivalence of F-TEDA-BF4 in acetonitrile (at −20 to +20°C) produced only 4,4-difluoro-3,5-dimethoxycyclohexa-2,5-dien-1-one (>50% yield), a conversion which was unaffected by carrying out the reaction in either aqueous acetonitrile (20 vol% H2O) or neat water. Treatment of 2,4,6-trimethoxytoluene with a two-molar equivalence of F-TEDA-BF4 in acetonitrile between −20 and +20°C gave the fluorodemethylation product 4-fluoro-3,5-dimethoxy-4- methylcyclohexa-2,5-dien-1-one in 81% yield. Download : Download full-size image