- Reagent-modulated optional site selectivities: The metalation of o-, m- and p-halobenzotrifluorides
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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.
- Mongin,Desponds,Schlosser
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Read Online
- Light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds
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Visible light-induced organic reactions are important chemical transformations in organic chemistry, and their efficiency highly depends on suitable photocatalysts. However, the commonly used photocatalysts are precious transition-metal complexes and elaborate organic dyes, which hamper large-scale production due to high cost. Here, for the first time, we report a novel strategy: light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds, allowing high-value-added aromatic ketones and carboxylic acids to be easily prepared in high-to-excellent yields using readily available alkyl arenes, methyl arenes and aldehydes as materials. The mechanistic investigations showed that the treatment of inexpensive and readily available sodium trifluoromethanesulfinate with oxygen under irradiation of light could in situ form a pentacoordinate sulfide intermediate as an efficient photosensitizer. The method represents a highly efficient, economical and environmentally friendly strategy, and the light and oxygen-enabled sodium trifluoromethanesulfinate photocatalytic system represents a breakthrough in photochemistry. This journal is
- Fu, Hua,Liu, Can,Liu, Yong,Yang, Haijun,Zhu, Xianjin
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supporting information
p. 4357 - 4363
(2020/07/14)
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- A general enantioselective route to the chamigrene natural product family
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Described in this report is an enantioselective route toward the chamigrene natural product family. The key disconnections in our synthetic approach include sequential enantioselective decarboxylative allylation and ring-closing olefin metathesis to form the all-carbon quaternary stereocenter and spirocyclic core present in all members of this class of compounds. The generality of this strategy is demonstrated by the first total syntheses of elatol and the proposed structure of laurencenone B, as well as the first enantioselective total syntheses of laurencenone C and α-chamigrene. A brief exploration of the substrate scope of the enantioselective decarboxylative allylation/ring-closing metathesis sequence with fully substituted vinyl chlorides is also presented.
- White, David E.,Stewart, Ian C.,Seashore-Ludlow, Brinton A.,Grubbs, Robert H.,Stoltz, Brian M.
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experimental part
p. 4668 - 4686
(2010/08/13)
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- The catalytic asymmetric total synthesis of elatol
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Described in this report is the first total synthesis of elatol, a halogenated sesquiterpene in the chamigrene natural product family. The key disconnections in our synthetic approach include an enantioselective decarboxylative allylation to form the all-carbon quaternary stereocenter and a ring-closing olefin metathesis to concomitantly form the spirocyclic core as well as the fully substituted chlorinated olefin. This strategy represents a general platform for accessing the chamigrene natural product family, as demonstrated by the synthesis of (+)-laurencenone B as an intermediate in our route. Copyright
- White, David E.,Stewart, Ian C.,Grubbs, Robert H.,Stoltz, Brian M.
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p. 810 - 811
(2008/09/20)
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- Dibenzyl Amine Compounds and Derivatives
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Dibenzyl amine compounds and derivatives, pharmaceutical compositions containing such compounds and the use of such compounds to elevate certain plasma lipid levels, including high density lipoprotein-cholesterol and to lower certain other plasma lipid le
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- Dibenzyl Amine Compounds and Derivatives
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Dibenzyl amine compounds and derivatives, pharmaceutical compositions containing such compounds and the use of such compounds to elevate certain plasma lipid levels, including high density lipoprotein-cholesterol and to lower certain other plasma lipid levels, such as LDL-cholesterol and triglycerides and accordingly to treat diseases which are exacerbated by low levels of HDL cholesterol and/or high levels of LDL-cholesterol and triglycerides, such as atherosclerosis and cardiovascular diseases in some mammals, including humans.
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- DIBENZYL AMINE COMPOUNDS AND DERIVATIVES
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Dibenzyl amine compounds and derivatives, pharmaceutical compositions containing such compounds and the use of such compounds to elevate certain plasma lipid levels, including high density lipoprotein-cholesterol and to lower certain other plasma lipid le
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