177420-64-3Relevant academic research and scientific papers
Regioselective halogen-metal exchange reaction of 3-substituted 1,2-dibromo arenes: The synthesis of 2-substituted 5-bromobenzoic acids
Menzel, Karsten,Dimichele, Lisa,Mills, Paul,Frantz, Doug E.,Nelson, Todd D.,Kress, Michael H.
, p. 1948 - 1952 (2008/02/08)
Regioselective halogen-metal exchange reactions using isopropylmagnesium chloride were carried out on 3-substituted 1,2-dibromo arenes. Eleven examples are given. Georg Thieme Verlag Stuttgart.
Halogen-metal exchange of 3-substituted 1,2-dibromoarenes: The use of long-range JCH coupling constants to determine regiochemistry
DiMichele, Lisa,Menzel, Karsten,Mills, Paul,Frantz, Doug,Nelson, Todd
, p. 1041 - 1043 (2008/02/05)
Regioselective halogen/metal exchange reactions were carried out on a series of 3-substituted-1,2-dibromoarenes. Product mixtures were quenched with CO2 to form the corresponding benzoic acid analogs to facilitate HPLC and NMR analysis. Substitution at the 3-position could readily be assigned on the basis of 2D HMBC long-range correlations, while assignment at the 2-position was not as straightforward. The use of three-bond JCH coupling constant measurements, extracted from 1-D 1H coupled 13C experiments, were necessary to render unequivocal regio assignments. Copyright
Relay propagation of crowding: The trifluoromethyl group as both an emitter and transmitter of steric pressure
Schlosser, Manfred,Cottet, Fabrice,Heiss, Christophe,Lefebvre, Olivier,Marull, Marc,Masson, Eric,Scopelliti, Rosario
, p. 729 - 734 (2007/10/03)
Whereas lithium 2,2,6,6-tetramethylpiperidide (LITMP) abstracts a proton exclusively from the 4-position of 3-bromobenzotrifluoride, the same base attacks selectively the 2-position when employed in the presence of N,N,N′,N″,N″-pentamethyldiethylenetriami
Reagent-modulated optional site selectivities: The metalation of o-, m- and p-halobenzotrifluorides
Mongin,Desponds,Schlosser
, p. 2767 - 2770 (2007/10/03)
Chloro(trifluoromethyl)benzenes and bromo(trifluoromethyl)benzenes undergo deprotonation at a position adjacent to the single halogen substituent when treated with alkyllithiums (at -75°C) and, respectively, lithium 2,2,6,6-tetramethylpiperidide (at -100°C) in tetrahydrofuran. Positional ambiguities, if existing, can be exploited to establish optional site selectivities. Thus, butyllithium reacts with 1-chloro-3-(trifluoromethyl)benzene under hydrogen/metal interconversion at the 2-position whereas sec-butyllithium attacks exclusively the 6-position. The latter mode of regioselectivity is also exhibited by 1-bromo-3-(trifluoromethyl)benzene in the presence of lithium 2,2,6,6-tetramethylpiperidide, only 2-bromo-4-(trifluoromethyl)phenyllithium being produced. 2-Bromo-6-(trifluoromethyl)phenyllithium is directly inaccessible, but is formed when 2-bromo-3-(trifluoromethyl)phenyllithium, generated at -100°C, is allowed to isomerize at -75°C.
