872545-52-3Relevant academic research and scientific papers
Fluorine-flanked congested sites: Minimal, though perceptible buttressing effects on the proton mobility of arenes
Heiss, Christophe,Leroux, Frederic,Schlosser, Manfred
, p. 5242 - 5247 (2005)
(2,6-Difluorophenyl)trimethylsilane, -triethylsilane and -triisopropylsilane undergo sec-butyllithium-mediated metalation at the 3- and 4-position (ortho and meta relative to the halogen) in ratios of 99.6:0.4, 98:2 and 95:5, respectively. The steric pressure transmitted by the fluorine atoms can be increased if the trialkylsilyl group is locked up on the other side by a relatively voluminous substituent. Whereas (2,6-difluorophenyl)triethylsilane is attacked by lithium 2,2,6,6-tetramethylpiperidide under deprotonation of the 4- and 5-position in a ratio of 99.4:0.6, the proportion of "ortho"/ "meta" metalation changes to 84:16 when (2-bromo-6-fluorophenyl) triethylsilane acts as the substrate. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
