Ligand-controlled divergent dehydrogenative reactions of carboxylic acids via C–H activation
Dehydrogenative transformations of alkyl chains to alkenes through methylene carbon-hydrogen (C–H) activation remain a substantial challenge. We report two classes of pyridine-pyridone ligands that enable divergent dehydrogenation reactions through palladium-catalyzed b-methylene C–H activation of carboxylic acids, leading to the direct syntheses of a,b-unsaturated carboxylic acids or g-alkylidene butenolides. The directed nature of this pair of reactions allows chemoselective dehydrogenation of carboxylic acids in the presence of other enolizable functionalities such as ketones, providing chemoselectivity that is not possible by means of existing carbonyl desaturation protocols. Product inhibition is overcome through ligand-promoted preferential activation of C(sp3)–H bonds rather than C(sp2)–H bonds or a sequence of dehydrogenation and vinyl C–H alkynylation. The dehydrogenation reaction is compatible with molecular oxygen as the terminal oxidant.
Wang, Zhen,Hu, Liang,Chekshin, Nikita,Zhuang, Zhe,Qian, Shaoqun,Qiao, Jennifer X.,Yu, Jin-Quan
p. 1281 - 1285
(2021/12/10)
N-Hydroxybenzimidazole inhibitors of ExsA MAR transcription factor in Pseudomonas aeruginosa: In vitro anti-virulence activity and metabolic stability
ExsA is a multiple adaptational response (MAR) transcription factor, regulating the expression of a virulence determinant, the type III secretion system (T3SS) in Pseudomonas aeruginosa. Non-cytotoxic, non-antibacterial N-hydroxybenzimidazoles were identified as effective inhibitors of ExsA-DNA binding, and their potential utility as anti-virulence agents for P. aeruginosa was demonstrated in a whole cell assay. Select N-hydroxybenzimidazole inhibitors were stable in an in vitro human liver microsomal assay.
Grier, Mark C.,Garrity-Ryan, Lynne K.,Bartlett, Victoria J.,Klausner, Kevin A.,Donovan, Peter J.,Dudley, Caroline,Alekshun, Michael N.,Ken Tanaka,Draper, Michael P.,Levy, Stuart B.,Kim, Oak K.
scheme or table
p. 3380 - 3383
(2010/08/06)
Synthesis of novel tetrahydroisoquinoline bronchodilators
The synthesis and bronchorelaxing effects of a series of novel tetrahydroisoquinoline amides are described. The compounds were evaluated for their ability to relax LTD4 contracted isolated human small airways ex-vivo. Several compounds demonstrated highly
Dalence-Guzmán, Maria F.,Toftered, J?rgen,Oltner, Viveca Thornqvist,Wensbo, David,Johansson, Martin H.
scheme or table
p. 4999 - 5003
(2010/10/05)
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