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(searched for: doi:10.1016/j.tetlet.2021.153458)
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, S. M. Basavarajaiah, K. Shyamsunder
Published: 25 January 2022
Molecular Diversity pp 1-23; https://doi.org/10.1007/s11030-022-10387-8

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Published: 17 January 2022
by MDPI
Abstract:
The reductive cyclization of suitably substituted organic nitro compounds by carbon monoxide is a very appealing technique for the synthesis of heterocycles because of its atom efficiency and easiness of separation of the only stoichiometric byproduct CO2, but the need for pressurized CO has hampered its diffusion. We have recently reported on the synthesis of indoles by reductive cyclization of o-nitrostyrenes using phenyl formate as a CO surrogate, using a palladium/1,10-phenanthroline complex as catalyst. However, depending on the desired substituents on the structure, the use of β-nitrostyrenes as alternative reagents may be advantageous. We report here the results of our study on the possibility to use phenyl formate as a CO surrogate in the synthesis of indoles by reductive cyclization of β-nitrostyrenes, using PdCl2(CH3CN)2 + phenanthroline as the catalyst. It turned out that good results can be obtained when the starting nitrostyrene bears an aryl substituent in the alpha position. However, when no such substituent is present, only fair yield of indole can be obtained because the base required to decompose the formate also catalyzes an oligo-polymerization of the starting styrene. The reaction can be performed in a single glass pressure tube, a cheap and easily available piece of equipment.
R. Nalini, S.M. Basavarajaiah, N.G. Yernale, K. Ramakrishna Reddy
Asian Journal of Chemistry, Volume 34, pp 389-394; https://doi.org/10.14233/ajchem.2022.23592

Abstract:
A new Schiff base ligand (E)-2-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)-N-(5- methyl-3-phenyl-1H-indol-2-yl)hydrazine carboxamide (L) (3) was synthesized by the reaction of N-(5-methyl-3-phenyl-1H-indol-2-yl)hydrazinecarboxamide (1) and 7-hydroxy-4-methyl-2-oxo-2Hchromene- 8-carbaldehyde (2). The Cu(II), Co(II), Ni(II) and Zn(II) metal complexes (4a-d) were synthesized and its structural elucidation was done by different spectral techniques. The Schiff base (3) behaves as ONO donor ligand and forms the complexes of the sort [M(L)(Cl)(H2O)2] for Cu(II) (4a) and Zn(II) (4d) and [M(L)2] for Co(II) (4b) and Ni(II) (4c). Compounds (3) and (4a-d) were tested in vitro for antimicrobial action, cytotoxicity property against Artemia salina and anti-tuberculosis assay against Mycobacterium tuberculosis (ATCC 25177). The metal complexes showed very good biological activity.
R. Nalini, S.M. Basavarajaiah, ,
Published: 19 November 2021
Journal of the Indian Chemical Society, Volume 99; https://doi.org/10.1016/j.jics.2021.100273

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