- BORAZANs: Tunable fluorophores based on 2-(pyrazolyl)aniline chelates of diphenylboron
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(Figure Presented) The reaction between 2-pyrazolyl-4-X-anilines, H(pzAnX), (X = para-OMe (L1), Me (L2), H (L3), Cl (L4), CO 2Et (L5), CF3 (L6), CN (L7)) and triphenylboron in boiling toluene affords the respective, highly emissive N,N′-boron chelate complexes, BPh2(pzAnX) (X = para-OMe (1), Me (2), H (3), Cl (4), CO2Et (5), CF3 (6), CN (7)) in high yield. The structural, electrochemical, and photophysical properties of the new boron complexes can be fine-tuned by varying the electron-withdrawing or -donating power of the para-aniline substituent (delineated by the substituent's Hammett parameter). Those complexes with electron-withdrawing para-aniline substituents such as CO2Et (5), CF3 (6), and CN (7) have more planar chelate rings, more 'quinoidal' disortion in the aniline rings, greater chemical stability, higher oxidation potentials, and more intense (φF = 0.81 for 7 in toluene), higher-energy (blue) fluorescent emission compared to those with electron-donating substituents. Thus, for 1 the oxidation potential is 0.53 V versus Ag/AgCl (compared to 1.12 V for 7), and the emission is tuned to the yellow-green but at an expense in terms of lower quantum yields (φF = 0.07 for 1 in toluene) and increased chemical reactivity. Density functional calculations (B3LYP/6-31G*) on PM3 energy-minimized structures of the ligands and boron complexes reproduced experimentally observed data and trends and provided further insight into the nature of the electronic transitions.
- Liddle, Brendan J.,Silva, Rosalice M.,Morin, Tyler J.,Macedo, Felipe P.,Shukla, Ruchi,Lindeman, Sergey V.,Gardinier, James R.
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- Cu(II)-catalyzed C-N coupling of (hetero)aryl halides and N-Nucleophiles promoted by α-benzoin oxime
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We first reported the new application of a translate metal chelating ligand α-benzoin oxime for improving Cu-catalyzed C-N coupling reactions. The system could catalyse coupling reactions of (hetero)aryl halides with a wide of nucleophiles (e.g., azoles, piperidine, pyrrolidine and amino acids) in moderate to excellent yields. The protocol allows rapid access to the most common scaαolds found in FDA-approved pharmaceuticals.
- Yuan, Chunling,Zhang, Lei,Zhao, Yingdai
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- L -(-) -Quebrachitol as a Ligand for Selective Copper(0)-Catalyzed N-Arylation of Nitrogen-Containing Heterocycles
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l-(-)-Quebrachitol (QCT) has been found as a ligand of copper powder for selective N-arylation of nitrogen-containing heterocycles with aryl halides. Furthermore, another potential catalytic system (copper powder/QCT/t-BuOK) was successfully adapted to unactivated aryl chlorides.
- Zhou, Qifan,Du, Fangyu,Chen, Yuanguang,Fu, Yang,Sun, Wenjiao,Wu, Ying,Chen, Guoliang
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p. 8160 - 8167
(2019/06/28)
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- Discovery of novel 2,4-diarylaminopyrimidine derivatives as potent and selective epidermal growth factor receptor (EGFR) inhibitors against L858R/T790M resistance mutation
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A series of novel 2,4-diarylaminopyrimidine derivatives of AZD9291 were discovered as L858R/T790M mutant selective epidermal growth factor receptor (EGFR) inhibitors. The majority of these compounds exhibited moderate to excellent EGFR T790 M/L858R inhibitory activities and comparable anti-proliferative activities against double mutant over-expressed NCI-H1975 cells to that of AZD9291. The most promising compounds 8a displayed an IC50 of 4.1 nM against EGFR L858R/T790M mutants. 8a also showed excellent cytotoxic effect against NCI-H1975 cells with an IC50 of 59 nM and 100-fold selectivity over wide-type EGFR over-expressed A431 cells. Compound 8a significantly inhibited tumor growth in NCI-H1975 xenograft models at a non-toxic dose. Docking study performed for 8a with ATP binding site of EGFR-TK showed the similar binding mode to that of AZD9291. All these results suggested that compound 8a was a potential mutant-selective EGFR inhibitor.
- Yan, Qi,Chen, Yuzhe,Tang, Baiyou,Xiao, Qiang,Qu, Rong,Tong, Linjiang,Liu, Jian,Ding, Jian,Chen, Yi,Ding, Ning,Tan, Wenfu,Xie, Hua,Li, Yingxia
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p. 298 - 306
(2018/05/22)
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- Copper(II)-Mediated ortho-Selective C(sp2)-H Tandem Alkynylation/Annulation and ortho-Hydroxylation of Anilides with 2-Aminophenyl-1H-pyrazole as a Directing Group
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2-Aminophenyl-1H-pyrazole has been identified as a viable directing group to promote copper(II)-mediated ortho-selective sp2 C-H bond tandem alkynylation/annulation of anilides with terminal alkynes to offer arylmethylene isoindolinones. Meanwhile, copper(II)-mediated ortho-selective sp2 C-H hydroxylation of anilides has also been optimized as the major reaction pathway by using Cu(OAc)2 as the promoter and 1,1,3,3-tetramethylguanidine as an organic base. Recovery of the directing group was achieved by hydrazinolysis for arylmethylene isoindolinones and basic hydrolysis for the hydroxylation products.
- Lee, Wan-Chen Cindy,Wang, Wei,Li, Jie Jack
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p. 2382 - 2388
(2018/02/23)
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- Palladium-Catalyzed Direct C(sp2)-H ortho-Arylation of Anilides Using 2-Aminophenylpyrazole as the Directing Group
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Palladium-catalyzed ortho-arylation of anilides was achieved using 2-aminophenyl-1H-pyrazole (2-APP) as a new directing group. Using Pd(OAc)2 as the catalyst and AgO as the promoter, mono- and diarylation of anilides were realized in up to 89% isolated yield. Further manipulation of the arylation product may be accomplished by a 2-step sequence involving an acidic hydrolysis of the methylated amide. More interestingly, in the presence of K2CO3, tandem C-C/C-N cyclization products were obtained for a couple of substrates.
- Shen, Yuning,Cindy Lee, Wan-Chen,Gutierrez, David A.,Li, Jie Jack
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p. 11620 - 11625
(2017/11/10)
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- Copper-mediated etherification of arenes with alkoxysilanes directed by an (2-aminophenyl)pyrazole group
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An efficient copper-mediated etherification of inert C-H bonds of (hetero)arenes with reagent-amounts of alkoxysilanes and alkanols has been developed using (2-aminophenyl)pyrazole (2-APP) as a removable directing group. The reaction is scalable, rapidly proceeds under an open atmosphere, and tolerates diverse functional groups to provide alkyl aryl ethers in high yields (up to 87%). As an application, the formal synthesis of anti-emetic drug metoclopramide is accomplished.
- Selvakumar, Jayaraman,Grandhi, Gowri Sankar,Sahoo, Harekrishna,Baidya, Mahiuddin
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p. 79361 - 79365
(2016/09/09)
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- 2-Aminophenyl-1H-pyrazole as a Removable Directing Group for Copper-Mediated C-H Amidation and Sulfonamidation
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2-Aminophenyl-1H-pyrazole was discovered as a removable bidentate directing group for copper-mediated aerobic oxidative C(sp2-H) bond amidation and sulfonamidation. When Cu(OAc)2 was employed as the copper source and 1,1,3,3-tetramet
- Lee, Wan-Chen Cindy,Shen, Yuning,Gutierrez, David A.,Li, Jie Jack
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p. 2660 - 2663
(2016/06/15)
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- Synthesis, antifungal activity and structure-activity relationships of novel 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid amides
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A series of novel 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid amides were synthesized and their activities were tested against seven phytopathogenic fungi by an in vitro mycelia growth inhibition assay. Most of them displayed moderate to excellent activities. Among them N-(2-(5-bromo-1H-indazol-1-yl)phenyl)-3-(difluoro-methyl)-1-methyl-1H-pyrazole-4-carboxamide (9m) exhibited higher antifungal activity against the seven phytopathogenic fungi than boscalid. Topomer CoMFA was employed to develop a three-dimensional quantitative structure-activity relationship model for the compounds. In molecular docking, the carbonyl oxygen atom of 9m could form hydrogen bonds towards the hydroxyl of TYR58 and TRP173 on SDH.
- Du, Shijie,Tian, Zaimin,Yang, Dongyan,Li, Xiuyun,Li, Hong,Jia, Changqing,Che, Chuanliang,Wang, Mian,Qin, Zhaohai
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p. 8395 - 8408
(2015/05/20)
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- 3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-arylation of imidazoles and 1H-pyrazole with aryl halides
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3-(Diphenylphosphino)propanoic acid (L2) has proved to be an efficient ligand for the copper-catalyzed CN coupling reactions. N-arylation of imidazoles with aryl iodides catalyzed by CuCl/L2 was smoothly carried out in DMSO at 100 °C with a yield up to 98%. N-arylation of 1H-pyrazole with aryl iodides and bromides catalyzed by Cu(OAc)2/L2 in 1,4-dioxane also gave the corresponding products with yields of 40%-98%.
- Liu, Ya-Shuai,Liu, Yan,Ma, Xiao-Wei,Liu, Ping,Xie, Jian-Wei,Dai, Bin
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p. 775 - 778
(2014/06/09)
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- Role of conformation and electronic structure in the chemistry of ground and excited state o-pyrazolylphenylnitrenes
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The chemistry of 2-(1-pyrazolyl)- (2a) and 2-[1-(3,5-dimethylpyrazolyl] phenylnitrene (2b) has been studied in EtOH solution at room temperature, in EtOH glasses at 90 K, and in Ar matrices at 12 K. These nitrenes were chosen as suitable models for clarifying the mechanism of intramolecular reactions because attack at the pyrazole ring can occur according to different modes and the asymmetry of the substituent gives rise to different conformations. Detailed DFT and CASSCF/CASPT2 studies on the conformation and decay paths of both spin states of the nitrenes have been carried out. Ring expansion to dehydroazepines (via benzoazirines) is calculated to be competitive in both nitrenes, but in the dimethyl derivative, 2b, attack onto the N lone pair (which is made more nucleophilic by the methyl groups) is favored. The higher barriers (by 4-8 kcal/mol) in singlet 2a cause 60-70% of this nitrene to decay by intersystem crossing to the triplet. Thus, the seemingly straightforward formation of benzo-fused heterocycles through intramolecular attack of the pyrazoline N lone pair by the singlet phenylnitrene can only overcome ring expansion and intermolecular reactions under favorable circumstances. The comparatively persistent triplet nitrenes are characterized in matrices, and the yields of photocyclization products (mainly pyrazolo[1,5-a]benzimidazole (7) from 2a and 5,6-dihydropyrazolo[1,5-a]quinoxaline (8) from 2b) are shown to depend on the preferred conformation of the starting azide and nitrene.
- Carra, Claudio,Bally, Thomas,Albini, Angelo
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p. 5552 - 5562
(2007/10/03)
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- Copper-diamine-catalyzed N-arylation of pyrroles, pyrazoles, indazoles, imidazoles, and triazoles
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This paper details the copper-catalyzed N-arylation of π-excessive nitrogen heterocycles. The coupling of either aryl iodides or aryl bromides with common nitrogen heterocycles (pyrroles, pyrazoles, indazoles, imidazoles, and triazoles) was successfully performed in good yield with catalysts derived from diamine ligands and CuI. General conditions were found that tolerate functional groups such as aldehydes, ketones, alcohols, primary amines, and nitriles on the aryl halide or heterocycle. Hindered aryl halides or heterocycles were also found to be suitable substrates using the conditions reported herein.
- Antilla, Jon C.,Baskin, Jeremy M.,Barder, Timothy E.,Buchwald, Stephen L.
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p. 5578 - 5587
(2007/10/03)
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- Solvent-free preparation of tris-pyrazolyl-1,3,5-triazines
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Tris-pyrazolyl-1,3,5-triazines have been prepared by cyclotrimerization of aromatic nitriles in solvent-free conditions. The interesting structures of these compounds make them candidates for application in coordination chemistry and crystal engineering.
- De La Hoz, Antonio,Díaz-Ortiz, Angel,Elguero, José,Martínez, Luis J.,Moreno, Andrés,Sánchez-Migallón, Ana
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p. 4397 - 4403
(2007/10/03)
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- Chemistry of Nitrenes Generated by the Photocleavage of Both Azides and a Five-Membered Heterocycle
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Pyrazolobenzotriazole and some of its derivatives (2a-c) are photochemically cleaved to form 2-(1-pyrazolyl)phenylnitrenes, which are also obtained through a more conventional path by photodecomposition of the pyrazolylphenyl azides (1a-c).Product
- Albini, A.,Bettinetti, G.,Minoli, G.
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p. 6928 - 6934
(2007/10/02)
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- Synthesis of 7-Substituted Indoles as Potential Ligand Precursors
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Some 7-(pyridin-2'-yl)- and 7-(pyrazol-1'-yl)-indole-2-carboxylic esters (14)-(16) and the related acids (17) and (18) have been synthesized through the Fischer indole cyclizations of the ethyl pyruvate hydrazones (9)-(12), which were in turn derived from
- Black, David St.C.,Deacon, Glen B.,Edwards, Gavin L.
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p. 1771 - 1781
(2007/10/02)
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- Heteropentalenes. The Thermal Addition of Pyrazolo- and Triazolobenzotriazoles to Dimethyl Acetylenedicarboxylate
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Pyrazolobenzotriazole (1a), 1,2,3-triazolobenzotriazole (1b), and 1,2,3-triazolobenzotriazole (1c) undergo electrophilic attack by dimethyl acetylenedicarboxylate to reversibly form diradical or zwitterionic intermediates, which then
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 2670 - 2676
(2007/10/02)
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- Competitive Cyclisations of Singlet and Triplet Nitrenes. Part 8. The 1-(2-Nitrenophenyl)pyrazoles and Related Systems
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The title nitrenes, derived by nitro-group deoxygenation with triethyl phosphite or by thermolysis or photolysis of the corresponding azide, have been studied.The effect of substituents (Cl, Br, OMe, NMe2, Me, CF3, and NO2) both meta and para to the nitrene has been examined as a determinant of the preferred mode of cyclisation to either a pyrazolobenzotriazole or a pyrazoloquinoxaline.Similarly, the role of solvents, sensitisers, and quenchers has been studied.Routes to the isomeric 1- and 2-(2-nitrophenyl)-4,5,6,7-tetrahydroindazoles have been defined and the literature corrected by studing the nitrene-mediated cyclisation of these products.The chemistry of the analogous 1-(2-carbenophenyl)- and the 1-(2-nitrenosulphonylphenyl)-3,5-dimethylpyrazoles has also been examined, the former giving 2-(3,5-dimethylpyrazol-1-yl)-benzaldazine and -benzyl alcohol while the latter gave products of intramolecular nitrene attack (a pyrazolobenzothiatriazine) and intermolecular reaction.Rationalisations for all the reaction pathways have been advanced.
- Lindley, John M.,McRobbie, Ian M.,Meth-Cohn, Otto,Suschitzky, Hans
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p. 982 - 994
(2007/10/02)
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