“On Water” Palladium Catalyzed Direct Arylation of 1H‐Indazole and 1H‐7‐Azaindazole
The C3 direct arylation of 1H-indazole and 1H-7-azaindazole has been a significant challenge due to the lack of the reactivity at this position. In this paper, we describe a mild and an efficient synthesis of new series of C3-aryled 1H-indazoles and C3-aryled 1H-7-azaindazoles via a C3 direct arylation using water as solvent. On water, PPh3 was effective as a ligand along with a lower charge of the catalyst Pd(OAc)2 (5 mol%) at 100 oC, leading to C3-aryled 1H-indazoles or C3-aryled 1H-7-azaindazoles in moderate to good yields.
[Bis-(trifluoroacetoxy)iodo]benzene-Mediated Oxidative Direct Amination C–N Bond Formation: Synthesis of 1H-Indazoles
An efficient [bis-(trifluoroacetoxy)iodo]benzene (PIFA)-mediated oxidative C-N bond formation is developed for the synthesis of 1H-indazoles from readily available arylhydrazones. The reaction tolerates a wide range of functional groups and has broad scope of substrates. Moreover, this method is a relative green and reliable method for rapid preparation of substituted 1H-indazoles under mild conditions.
Divergent Synthesis of 1H-Indazoles and 1H-Pyrazoles from Hydrazones via Iodine-Mediated Intramolecular Aryl and sp3 C–H Amination
A divergent intramolecular C–H amination of hydrazones has been developed employing molecular iodine (I2) as the sole oxidant. The required hydrazone substrates were readily obtained by condensation of hydrazines with the corresponding ketones.
An efficient transition-metal-free synthesis of 1H-indazoles from arylhydrazones with montmorillonite K-10 under O2 atmosphere
An efficient transition-metal-free synthetic method of 1H-indazoles has been developed. The reaction of arylhydrazones in the presence of montmorillonite K-10 in 1,2-dichlorobenzene at 130 °C afforded 1H-indazoles in good yields most likely via a sequenti
Yu, Jin,Lim, Jin Woo,Kim, Su Yeon,Kim, Jimin,Kim, Jae Nyoung
supporting information
p. 1432 - 1436
(2015/03/04)
Facile access to 1H-indazoles through iodobenzene-catalyzed C-H amination under mild, transition-metal-free conditions
The transition-metal- and halogen-free synthesis of N-aryl-substituted 1H-indazole and derivatives was accomplished on the basis of the iodobenzene-catalyzed intramolecular C-H amination of hydrazones under mild conditions. Reactions of hydrazones derived
Copper-catalyzed aerobic C(sp2)-H functionalization for C-N bond formation: Synthesis of pyrazoles and indazoles
A simple, practical, and highly efficient synthesis of pyrazoles and indazoles via copper-catalyzed direct aerobic oxidative C(sp2)-H amination has been reported herein. This process tolerated a variety of functional groups under mild conditions. Further diversification of pyrazoles was also investigated, which provided its potential for drug discovery.
The first example of intermolecular C-H arylation of substituted 1H-indazoles is reported. Various 1-substituted indazoles were used as starting materials, and (hetero)aryl bromides and iodides were investigated as coupling partners. Different reaction co
Ben-Yahia, Ali,Naas, Mohammed,El Kazzouli, Said,Essassi, El Mokhtar,Guillaumet, Gerald
p. 7075 - 7081
(2013/02/22)
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.