- Ligand-Enabled γ-C(sp3)?H Olefination of Free Carboxylic Acids
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We report the ligand-enabled C?H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.
- Ghiringhelli, Francesca,Ghosh, Kiron Kumar,Mondal, Arup,Uttry, Alexander,Wedi, Philipp,van Gemmeren, Manuel
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p. 12848 - 12852
(2020/06/25)
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- Catalytic asymmetric bromine-lithium exchange: A new tool to build axial chirality
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We present here the first catalytic desymmetrization of the 2,2′,6,6′-tetrabromobiphenyl 1 and analogues, by a bromine-lithium exchange catalyzed by either diamines or diether derivatives (0.5 equiv.), yielding axially chiral compounds in high yield (up to 89%) and high enantioselectivity (up to 82%).
- Perron, Quentin,Alexakis, Alexandre
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supporting information; experimental part
p. 2611 - 2620
(2011/01/05)
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- HEPATITIS C INHIBITOR DIPEPTIDE ANALOGS
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The present invention relates to compounds of formula (I): wherein R1, R2, R4, n and m are as defined herein and R3 is selected from: (i) -C(O)OR31 wherein R31 is (C1-6)alkyl or aryl, wherein the (C1-6)alkyl is optionally substituted with one to three halogen substituents; (ii) -C(O)NR32R33, wherein R32 and R33 are each independently selected form H, (C1-6)alkyl, and Het; (iii) -SOvR34, wherein v is 1 or 2 and R34 is selected from: (C1-6)alkyl, aryl, Het, and NR32R33 wherein R32 and R33 are as defined above; and (iv) -CO(O)-R35, wherein R35 is selected from (C1-8)alkyl, (C3-7)cycloalkyl-(C1-4)alkyl, aryl, aryl-(C1-6)alkyl, Het and Het-(C1-6)alkyl, each of which are optionally substituted with one or more substituents each independently selected from halo, (C1-6)alkyl, (C3-7)cycloalkyl, aryl, Het, hydroxyl, -O-(C1-6)alkyl, -S-(C1-6)alkyl, -SO-(C1-6)alkyl, -SO2-(C1-6)alkyl, -O-aryl, -S-aryl, -SO-aryl and -SO2-aryl, wherein the aryl portion of the -O-aryl, -S-aryl, -SO-aryl and -SO2-aryl are each optionally substituted with one to five halo substituents. The present invention further relates to pharmaceutical compositions containing the compounds of formula (I) and methods for using these analogs in the treatment of HCV infection.
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Page/Page column 85-86
(2008/06/13)
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- Processes for producing aromatic polycarbonate oligomer and aromatic polycarbonate
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A process for producing continuously an aromatic polycarbonate oligomer by reacting an aromatic dihydroxy compound and an alkali metal base or an alkaline earth metal base with a carbonyl halide compound comprises: (1) feeding continuously to a tank reactor an aromatic dihydroxy compound, water, a molecular weight controlling agent, a polymerization catalyst, a carbonyl halide compound, and an organic solvent, and an alkali metal base or an alkaline earth metal base in an amount of 1.15-1.6 equivalents based on the aromatic dihydroxy compound, (2) carrying out the reaction with a residence time as defined by the following formula, where X is an amount of the polymerization catalyst in terms of mole % based on the amount of mole of the aromatic dihydroxy compound fed per unit time, and Y is a residence time (min.), and (3) continuously withdrawing the reaction mixture from the tank reactor to obtain an aromatic polycarbonate oligomer having a number average molecular weight of 1,000-10,000. An aromatic polycarbonate is produced by polycondensation of the aromatic polycarbonate oligomer.
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- Improved Synthesis of Tertiary Alkylacetic Acids and Esters
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Tertiary alkylacetic acids (R3CCH2COOH) are prepared by reaction of 1,1-dichloroethene with a reagent capable of forming readily a tertiary alkyl carbenium ion with sulfuric acid in the absence of boron trifluoride.With tertiary butyl reagents, the yields are good and the method is convenient at laboratory and larger scales.The yields of carboxylic acids fall sharply with increasing steric effects.The esters are obtained directly, by adding alcohols, in a one-pot synthesis; with C1-C3 alcohols the reaction is selective.
- Randriamahefa, S.,Deschamps, P.,Gallo, R.,Grangette, H.
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p. 493 - 495
(2007/10/02)
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