- Regioselective C3-H Trifluoromethylation of 2 H-Indazole under Transition-Metal-Free Photoredox Catalysis
-
Trifluoromethyl-substituted heteroarenes are biologically active compounds and useful building blocks. In this sequence, we have developed a visible-light-promoted regioselective C3-H trifluoromethylation of 2H-indazole under metal-free conditions, which
- Murugan, Arumugavel,Babu, Venkata Nagarjuna,Polu, Ashok,Sabarinathan, Nagaraj,Bakthadoss, Manickam,Sharada, Duddu S.
-
p. 7796 - 7803
(2019/06/27)
-
- Synthesis of NN palladium complexes and six-membered CN palladacycles from 1-N- and 2-N-benzylindazoles
-
The reaction of 1-N-benzylindazole (1) and 2-N-benzylindazole (1a) with Na2PdCl4 in MeOH afforded the NN coordinated complexes Pd(1)2Cl2 (2) as the only trans-isomer and Pd(1a)2Cl2 (2a) as the 1:1 mixture of cis and trans isomers. Direct palladation of 1 and 1a using Pd(OAc)2 in AcOH led to the corresponding μ-acetato-dimeric complexes (3 and 3a) with six-membered palladacycles as the mixtures of syn and anti isomers. The reaction of 3 and 3a with LiCl in aqueous acetone gave the μ-Cl-dimeric complexes 5 and 5a where the acetate groups were replaced by Cl. The following addition of PPh3 to the solution of 5 and 5a in CH2Cl2 generated the mononuclear adducts 7 and 7a. NMR spectroscopy data supported the proposed structures of all complexes. The solid-state structure of 7 and 7a was determined by the single-crystal X-ray diffraction methods and indicated a boat conformation of both 6-membered palladacycles.
- Bulygina, Ludmila A.,Khrushcheva, Natalya S.,Klemenkova, Zinaida S.,Lyssenko, Konstantin A.,Peregudov, Aleksander S.,Sokolov, Viacheslav I.
-
p. 391 - 397
(2018/03/29)
-
- A General One-Pot Synthesis of 2H-Indazoles Using an Organophosphorus–Silane System
-
A simple and direct approach for the regioselective construction of the privileged 2H-indazole scaffold is described. The developed one-pot strategy involves phospholene-mediated N?N bond formation to access 2H-indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2-nitrobenzaldehydes and primary amines, a mild reductive cyclization, involving the use of commercially available phospholene oxide and silanes, delivered a wide variety of substituted 2H-indazoles in good to excellent yields.
- Schoene, Jens,Bel Abed, Hassen,Schmieder, Peter,Christmann, Mathias,Nazaré, Marc
-
supporting information
p. 9090 - 9100
(2018/06/29)
-
- A VERSATILE LIGAND FOR PALLADIUM-CATALYZED META-C-H FUNCTIONALIZATIONS
-
A class of mono-protected 3-amino-2- hydroxypyridine (MPAHP) ligands that enable the meta- C-H arylation of anilines, phenols, phenylacetic acids, and biologically relevant heterocyclic compounds using norbornene as a transient mediator is disclosed. The applicability of this meta-arylation methodology in the pharmaceutical industry is illustrated for heteroaryl substrates and heteroaryl iodide coupling partners, a feat made possible by using the MPAHP ligand. The enabling nature of MPAHP ligands to achieve other meta-C-H functionalization processes is also illustrated by the development of a meta-C-H amination reaction and a meta-C-H alkynylation reaction.
- -
-
Page/Page column 96; 97
(2017/11/15)
-
- A Biphilic Phosphetane Catalyzes N-N Bond-Forming Cadogan Heterocyclization via PIII/PV = O Redox Cycling
-
A small-ring phosphacycle, 1,2,2,3,4,4-hexamethylphosphetane, is found to catalyze deoxygenative N-N bond-forming Cadogan heterocyclization of o-nitrobenzaldimines, o-nitroazobenzenes, and related substrates in the presence of hydrosilane terminal reductant. The reaction provides a chemoselective catalytic synthesis of 2H-indazoles, 2H-benzotriazoles, and related fused heterocyclic systems with good functional group compatibility. On the basis of both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic PIII/PV = O cycling, where DFT modeling suggests a turnover-limiting (3+1) cheletropic addition between the phosphetane catalyst and nitroarene substrate. Strain/distortion analysis of the (3+1) transition structure highlights the controlling role of frontier orbital effects underpinning the catalytic performance of the phosphetane.
- Nykaza, Trevor V.,Harrison, Tyler S.,Ghosh, Avipsa,Putnik, Rachel A.,Radosevich, Alexander T.
-
p. 6839 - 6842
(2017/05/29)
-
- Ligand-Promoted Meta-C-H Arylation of Anilines, Phenols, and Heterocycles
-
Here we report the development of a versatile 3-acetylamino-2-hydroxypyridine class of ligands that promote meta-C-H arylation of anilines, heterocyclic aromatic amines, phenols, and 2-benzyl heterocycles using norbornene as a transient mediator. More than 120 examples are presented, demonstrating this ligand scaffold enables a wide substrate and coupling partner scope. Meta-C-H arylation with heterocyclic aryl iodides as coupling partners is also realized for the first time using this ligand. The utility for this transformation for drug discovery is showcased by allowing the meta-C-H arylation of a lenalidomide derivative. The first steps toward a silver-free protocol for this reaction are also demonstrated.
- Wang, Peng,Farmer, Marcus E.,Huo, Xing,Jain, Pankaj,Shen, Peng-Xiang,Ishoey, Mette,Bradner, James E.,Wisniewski, Steven R.,Eastgate, Martin D.,Yu, Jin-Quan
-
supporting information
p. 9269 - 9276
(2016/08/05)
-
- Indazolium halides as efficient ligands for Pd-catalyzed Suzuki–Miyaura cross-coupling of aryl bromides with arylboronic acids
-
The indazolium halides containing various N-substituents have been conveniently prepared and applied in the palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl bromides with arylboronic acids at mild reaction conditions. The cross-coupling reaction provides the desired products in good to high yields. The ease of synthesis and the modularity, and the broad range of aryl bromides and arylboronic acids make this type of ligand attractive and promising for transition metal catalysis.
- Chen, Qian,Mao, Zhuqing,Guo, Fang,Liu, Xiaoshuang
-
supporting information
p. 3735 - 3738
(2016/07/26)
-
- Regioselective synthesis of 2H-indazoles through Ga/Al- and Al-mediated direct alkylation reactions of indazoles
-
A procedure has been developed for the regioselective, high yielding synthesis of 2H-indazoles that involves direct alkylation of indazoles with various allyl and benzyl bromides, and α-bromocarbonyl compounds.
- Lin, Mei-Huey,Liu, Han-Jun,Lin, Wei-Cheng,Kuo, Chung-Kai,Chuang, Tsung-Hsun
-
supporting information
p. 11376 - 11381
(2015/11/27)
-
- Regioselective synthesis of 2 H-indazoles using a mild, one-pot condensation-cadogan reductive cyclization
-
An operationally simple and efficient one-pot synthesis of 2H-indazoles from commercially available reagents is reported. Ortho-imino-nitrobenzene substrates, generated via condensation, undergo reductive cyclization promoted by tri-n-butylphosophine to afford substituted 2H-indazoles under mild reaction conditions. A variety of electronically diverse ortho-nitrobenzaldehydes and anilines were examined. To further extend the scope of the transformation, aliphatic amines were also employed to form N2-alkyl indazoles selectively under the optimized reaction conditions.
- Genung, Nathan E.,Wei, Liuqing,Aspnes, Gary E.
-
p. 3114 - 3117
(2014/06/23)
-
- A facile synthesis of 2H-indazoles under neat conditions and further transformation into aza-γ-carboline alkaloid analogues in a tandem one-pot fashion
-
We have described a facile, microwave-assisted, catalyst-free and solvent-free approach to 2H-indazoles and further developed a robust tandem one-pot metal-free strategy for C-C bond formation at the C-3 position of 2H-indazoles leading to a unique class
- Vidyacharan, Shinde,Sagar,Chaitra,Sharada, Duddu S.
-
p. 34232 - 34236
(2014/11/07)
-
- Pd- and Cu-catalyzed C-H arylation of indazoles
-
The palladium- and copper-catalyzed C-H arylation reactions of 1H- and 2H-indazoles with haloarenes are described. A PdCl2/phen/Ag 2CO3/K3PO4 catalytic system is effective for the C-H arylation of 1H- and 2H-indazoles with haloarenes, whereas a less expensive CuI/phen/LiOt-Bu catalytic system is applicable to the C-H coupling of substituted 2H-indazoles and iodoarenes. The utility of newly developed catalyst was demonstrated in the rapid synthesis of YC-1 (an antitumor agent) and YD-3 (platelet anti-aggregating agent). These new reactions represent important direct functionalization tools of indazoles, well-known bioisosteres of pharmaceutically important indole core.
- Hattori, Keika,Yamaguchi, Kazuya,Yamaguchi, Junichiro,Itami, Kenichiro
-
experimental part
p. 7605 - 7612
(2012/09/07)
-
- Ionic diamine rhodium complex catalyzed reductive N-heterocyclization of N-(2-nitroarylidene)amines
-
Ionic diamine rhodium complexes catalyze the reductive N-heterocyclization of N-(2-nitroarylidene)amines under carbon monoxide to afford the corresponding 2H-indazoles in up to 75% yields.
- Okuro, Kazumi,Gurnham, Joanna,Alper, Howard
-
scheme or table
p. 620 - 622
(2012/02/15)
-
- A general and efficient approach to 2H-indazoles and 1H-pyrazoles through copper-catalyzed intramolecular N-N bond formation under mild conditions
-
A new efficient copper-catalyzed intramolecular amination reaction has been developed to readily synthesise a wide variety of multi-substituted 2H-indazole and 1H-pyrazole derivatives from easily accessible starting materials under mild conditions. A highly selective ligand for estrogen receptor β was prepared in three steps by employing this method. The Royal Society of Chemistry 2011.
- Hu, Jiantao,Cheng, Yongfeng,Yang, Yiqing,Rao, Yu
-
p. 10133 - 10135
(2011/10/09)
-
- SYNTHESIS BY PHASE TRANSFER CATALYSIS OF N-BENZYL, N-DIPHENYLMETHYL AND N-TRIPHENYLMETHYL AZOLES AND BENZAZOLES: PROTON NMR AND CHROMATOGRAPHIC DATA AS A TOOL FOR IDENTIFICATION
-
Pyrazole, imidazole, 1,2,4-triazole, indazole and benzotriazole were alkylated under phase transfer catalysis (PTC) with benzyl-, diphenylmethyl- and trityl chloride.Alkylation occured only at the ring nitrogen atoms of the heterocycle, except for indazole in which substitution took also place at position 3.A systematic study of the N- and C-substituted derivatives by proton NMR and chromatographic techniques has been done.
- Claramunt, Rosa M.,Elguero, Jose,Garceran, Rafael
-
p. 2895 - 2906
(2007/10/02)
-