134965-26-7Relevant academic research and scientific papers
Fluoronaphthalene building blocks via arynes: A solution to the problem of positional selectivity
Masson, Eric,Schlosser, Manfred
, p. 4401 - 4405 (2007/10/03)
When 3-fluoro- and 3-chloro-1,2-didehydrobenzenes are generated in the presence of 2-(trimethylsilyl)furan, two regioisomeric cycloadducts are formed in a 1:2 ratio. However, regioselectivity can be installed by fitting one bulky trimethylsilyl group into sterically critical positions of each of the two reaction components. Thus 3-fluoro-6-trimethylsilyl-1,2-didehydrobenzene and 2-(trimethylsilyl)furan give one cycloadduct exclusively. In this way, the Diels-Alder reaction between suitably adorned arynes and similarly designed furans can open an entry to naphthalene derivatives that have unprecedented substituent patterns that qualify them as building blocks for pharmaceutical or agricultural research. The acid-catalyzed isomerization of model 1,4-epoxy-1,4-dihydronaphthalenes, the aryne/furan cycloadducts, exhibits unexpected effects on rates and regioselectivity. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Fluorine Deshielding in the Proximity of a Methyl Group. An Experimental and Theoretical Study
Gribble, Gordon W.,Keavy, Daniel J.,Olson, Erik R.,Rae, Ian D.,Staffa, Alfred,et al.
, p. 422 - 432 (2007/10/02)
19F chemical shifts are reported for a series of alkyl-substituted fluoronaphthalenes and related compounds that exhibit steric crowding around the fluorine atom due to the proximity of methyl groups.Comparisons of these chemical shifts with others measured in similar compounds but without the corresponding methyl groups show that this crowding effect produces a large low-field shift of the 19F signal.Similar effects, but with an even larger sensitivity to the steric crowding, were recently reported for 17O chemical shifts.The electronic origin for this proximity effect on 19F chemical shifts is analyzed within the molecular orbital theory, at the INDO level, using the inner projections of the polarization propagator technique.It is found that the presence of the methyl group produces an increase in the absolute value of the paramagnetic term of the magnetic shielding constant.Key words - 19F NMR, 1-Alkyl-8-fluoronaphthalenes, Fluorine deshielding, 19F chemical shift theory, Magnetic shielding tensor calculations
