- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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supporting information
p. 5022 - 5037
(2021/05/04)
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- Synthesis and bioactivities of diamide derivatives containing a phenazine-1-carboxamide scaffold
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Taking natural product phenazine-1-carboxamide (PCN) as a lead compound, a series of novel phenazine-1-carboxylic acid diamide derivatives were designed and synthesised. Their structures were confirmed by 1H-NMR and HRMS. The bioassays showed that some of the target compounds exhibited promising in vitro fungicidal activities, and exhibited excellent and selective herbicidal activities. Particularly, compounds c, h, o and s displayed root length inhibition activities against barnyard grass with the rate of more than 80%. Compound c exhibited the best activity among all the target compounds against barnyard grass stalk length with the IC50 value of 0.158?mmol/L, and compound o exhibited the best and wide spectrum inhibition against barnyard grass root length and rape in both root length and stalk length herbicidal activities with its IC50 values of 0.067, 0.048 and 0.059?mmol/L respectively. The analysis of preliminary Structure-Activity Relationships provides the theoretical basis for further design of phenazine-1-carboxylic acid.
- Zhu, Xiang,Zhang, Min,Yu, Linhua,Xu, Zhihong,Yang, Dan,Du, Xiaoying,Wu, Qinglai,Li, Junkai
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supporting information
p. 2453 - 2460
(2018/03/29)
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- 4-Quinolone-3-carboxylic acids as cell-permeable inhibitors of protein tyrosine phosphatase 1B
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Protein tyrosine phosphatase 1B is a negative regulator in the insulin and leptin signaling pathways, and has emerged as an attractive target for the treatment of type 2 diabetes and obesity. However, the essential pharmacophore of charged phosphotyrosine or its mimetic confer low selectivity and poor cell permeability. Starting from our previously reported aryl diketoacid-based PTP1B inhibitors, a drug-like scaffold of 4-quinolone-3-carboxylic acid was introduced for the first time as a novel surrogate of phosphotyrosine. An optimal combination of hydrophobic groups installed at C-6, N-1 and C-3 positions of the quinolone motif afforded potent PTP1B inhibitors with low micromolar IC 50 values. These 4-quinolone-3-carboxylate based PTP1B inhibitors displayed a 2-10 fold selectivity over a panel of PTP's. Furthermore, the bidentate inhibitors of 4-quinolone-3-carboxylic acids conjugated with aryl diketoacid or salicylic acid were cell permeable and enhanced insulin signaling in CHO/hIR cells. The kinetic studies and molecular modeling suggest that the 4-quinolone-3-carboxylates act as competitive inhibitors by binding to the PTP1B active site in the WPD loop closed conformation. Taken together, our study shows that the 4-quinolone-3-carboxylic acid derivatives exhibit improved pharmacological properties over previously described PTB1B inhibitors and warrant further preclinical studies.
- Zhi, Ying,Gao, Li-Xin,Jin, Yi,Tang, Chun-Lan,Li, Jing-Ya,Li, Jia,Long, Ya-Qiu
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p. 3670 - 3683
(2014/07/07)
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- Piperazine derivatives: Synthesis, inhibition of the Mycobacterium tuberculosis enoyl-acyl carrier protein reductase and SAR studies
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The Mycobacterium tuberculosis NADH-dependent enoyl-acyl carrier protein reductase (MtInhA) catalyzes hydride transfer to long-chain enoyl thioester substrates. MtInhA is a member of the mycobacterial type II dissociated fatty acid biosynthesis system, and is the bona fide target for isoniazid, the most prescribed drug for tuberculosis treatment. Here, a series of piperazine derivatives was synthesized and screened as MtInhA inhibitors, which resulted in the identification of compounds with IC50 values in the submicromolar range. A structure-activity relationship (SAR) evaluation indicated the importance of the chemical environment surrounding the carbonyl group for inhibition. In addition, the structure of one selected compound was supported by crystallographic studies, and experimental geometrical values were compared with semi-empirical quantum chemical calculations. Furthermore, the mode of inhibition and inhibitory dissociation constants were determined for the nine most active compounds. These findings suggest that these 9H-fluoren-9-yl-piperazine-containing compounds interact with MtInhA at the enoyl thioester (2-trans-dodecenoyl-CoA) substrate binding site.
- Rotta, Mariane,Pissinate, Kenia,Villela, Anne Drumond,Back, Davi Fernando,Timmers, Luis Fernando Saraiva MacEdo,Bachega, Jos Fernando Ruggiero,De Souza, Osmar Norberto,Santos, Digenes Santiago,Basso, Luiz Augusto,MacHado, Pablo
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p. 436 - 447
(2015/08/19)
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- Characterization of the histamine H4 receptor binding site. Part 1. Synthesis and pharmacological evaluation of dibenzodiazepine derivatives
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A series of dibenzodiazepine derivatives was synthesized to probe the binding site of the recently discovered histamine H4 receptor (H 4R). Optimization of the lead structure clozapine (2) resulted in (E)-7-chloro-11(4-methylpiperazin-1-yl)dibenzo[b,f][1,4]oxazepine (7j), a potent H4R agonist (H4R, pK, = 7.6). Pharmacological data suggests that the series of nonimidazole compounds can be used to describe the orthosteric binding site of the H4R because both 2 and 7j displace [3H]histamine in a competitive manner. Furthermore, it is demonstrated that the effects of 7j are competitively antagonized by the selective H4R antagonist JNJ 7777120 (1), indicating considerable overlap of their binding sites. On the basis of the derived structure-activity relationships and additional pharmacological results, a pharmacophore model was constructed, which will be the premise for the design of novel H4R ligands.
- Smits, Rogier A.,Lim, Herman D.,Stegink, Bart,Bakker, Remko A.,De Esch, Iwan J. P.,Leurs, Rob
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p. 4512 - 4516
(2007/10/03)
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