6833-51-8Relevant articles and documents
Photocarboxylation of Benzylic C-H Bonds
Meng, Qing-Yuan,Schirmer, Tobias E.,Berger, Anna Lucia,Donabauer, Karsten,K?nig, Burkhard
supporting information, p. 11393 - 11397 (2019/08/20)
The carboxylation of sp3-hybridized C-H bonds with CO2 is a challenging transformation. Herein, we report a visible-light-mediated carboxylation of benzylic C-H bonds with CO2 into 2-arylpropionic acids under metal-free conditions. Photo-oxidized triisopropylsilanethiol was used as the hydrogen atom transfer catalyst to afford a benzylic radical that accepts an electron from the reduced form of 2,3,4,6-tetra(9H-carbazol-9-yl)-5-(1-phenylethyl)benzonitrile generated in situ. The resulting benzylic carbanion reacts with CO2 to generate the corresponding carboxylic acid after protonation. The reaction proceeded without the addition of any sacrificial electron donor, electron acceptor or stoichiometric additives. Moderate to good yields of the desired products were obtained in a broad substrate scope. Several drugs were successfully synthesized using the novel strategy.
Structural requirements for substrate in highly enantioselective hydrogenation over the cinchonidine-modified Pd/C
Sugimura, Takashi,Uchida, Takayuki,Watanabe, Junya,Kubota, Takeshi,Okamoto, Yasuaki,Misaki, Tomonori,Okuyama, Tadashi
experimental part, p. 57 - 64 (2009/06/17)
Relationship between substrate structure and enantioselectivity is studied for the asymmetric hydrogenation of 42 different (E)-α, β-disubstituted acrylic acids (propenoic acids) over cinchonidine-modified Pd/C. The β-phenyl group is indispensable for high enantioselectivity of α-phenylcinnamic acid (2,3-diphenylpropenoic acid, 81% ee), and substitution on this group affects markedly the selectivity. The high ee up to 92% was achieved by the β - p-alkoxyphenyl substitution, and the selectivity is ascribed mainly to stronger interaction of the substrate with the chiral modifier on the catalyst surface. In contrast, substitution on the α-phenyl group does not affect notably the enantioselectivity (80-82% ee) or even the α-phenyl group itself is not indispensable but replaceable with a properly bulky group for the high enantioselectivity.
Synthesis of Acenaphthene-1-carboxylic Acid Using Lithiated Tris(methylthio)methane to Carboxylate 1-Bromoacenaphthene
Halfpenny, Paul R.,Horwell, David C.,Rees, David C.
, p. 517 - 519 (2007/10/02)
A new synthesis of acenaphthene-1-carboxylic acid (4) in 3 steps and 78 percent overall yield from 1-bromoacenaphthene (1) is described.In the key step, lithiated tris(methylthio)methane is reacted with 1-bromoacenaphthene to give 1-acenaphthene (2).Methanolysis of 2 gives racemic methyl acenaphthene-1-carboxylate 3, which is resolved by chiral chromatography.The usefulness of tris(methylthio)methyllithium as a carboxyl carbanion equivalent is illustrated by the conversion of three other bromides to the corresponding methoxycarbonyl derivatives.
Pigment composition
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, (2008/06/13)
A pigment composition contains a pigment and a dispersant. The dispersant is a phosphoric ester compound represented by the following general formula: wherein at least one of the three Rs is a residuum of a polyester chain containing as principal bonds thereof ester bonds of a polycarboxylic acid and a polyalcohol.
Pigment composition
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, (2008/06/13)
A pigment composition contains a pigment and a dispersant. The dispersant is a polyester compound which contains, per molecule, a residuum of at least two benzene rings coupled together, an aromatic ring having at least 8 carbon atoms or a heterocyclic ring having at least 8 carbon atoms, and at least one ester bond as a principal bond.
A Simple Route to Racemic Acenaphthene-1-carboxylic Acid via Hydroformylation of Acenaphthylene
Raffaelli, Andrea,Rosini, Carlo,Dini, Massimo,Salvadori, Piero
, p. 893 - 894 (2007/10/02)
Hydroformylation of acenaphthylene using di-μ-chlorotetracarbonyldirhodium/triphenylphosphine as catalytic precursor affords acenaphthene-1-carboxaldehyde under mild conditions in 80percent yield.This compound is easily transformed, via dehydration of the corresponding oxime followed by hydrolysis of the nitrile, into acenaphthene-1-carboxylic acid in an overall yield of ca. 50percent.