CuO nanoparticle catalysed synthesis of 2H-indazoles under ligand free conditions
作者:Nilufa Khatun、Anupal Gogoi、Pallabita Basu、Prasenjit Das、Bhisma K. Patel
DOI:10.1039/c3ra45298k
日期:——
A CuO nano catalysed one-pot synthesis of 2H-indazoles has been devised from easily accessible starting materials viz. 2-bromobenzaldehydes, primary amines and sodium azide under ligand free conditions. The nano CuO catalyst played an important role during the formation of the intermolecular C–N bond followed by the intramolecular N–N bond, providing 2H-indazoles. This method has a broad substrate scope with a high tolerance of a variety of functional groups. The catalyst can be recycled up to three times, however with slight decreases in the yields each time.
Synthesis of 2H-indazoles via the Cadogan reaction in batch and flow mode
作者:Matilda Duffy、Mara Di Filippo、Marcus Baumann
DOI:10.1016/j.tetlet.2021.153522
日期:2021.12
A continuous flow protocol is reported for the synthesis of 2H-indazoles via the thermal Cadogan reaction. Triethyl phosphite serves as a readily available deoxygenation reagent providing a facile entry to a series of drug-like 2H-indazoles in high chemical yields. Compared to an analogous batch approach, the flow process was advantageous as it provides for a contained environment where boiling of
The dichlorobis(triphenylphosphine)palladium (PdCl2(PPh(3))(2))-tin(II) chloride (SnCl2) system shows high catalytic activity for the reductive N-heterocyclization of various 2-nitrostyrene and N-(2-nitrobenzylidene)amine derivatives when employed at 100 degrees C for 16 h under 20 kg cm(-2) of initial carbon monoxide pressure, to give the corresponding indole and 2H-indazole derivatives in good yield. For example, 2-phenylindole was obtained in 75% yield from the reductive N-heterocyclization of 2-nitrostilbene. Similarly, 2-propyl-2H-indazole was readily prepared in 83% yield by the reductive N-heterocyclization of N-(2-nitrobenzylidene)propylamine. A nitrene intermediate for the present reaction is proposed on the basis of deuterium-labeling experiments and the investigation of alkyl rearrangement in the construction of the indole skeleton. Carbon monoxide effectively operates as a deoxygenating agent of the nitro group to afford a nitrene intermediate.
Akazome Motohiro, Kondo Teruyuki, Watanabe Yoshihisa, J. Org. Chem, 59 (1994) N 12, S 3375-3380
A novel series of bis Indy-NHC gold complexes have been developed and investigated via a mild Ag-carbene transfer route. The obtained complexes were characterized by NMR spectroscopy and X-ray diffraction analysis. The catalytic property of these gold complexes was further evaluated in the oxidation of benzylic. The gold complex E1 showed a high catalytic activity in the oxidation of various benzylic