Keesara Srinivas

Thiopseudourea ligated palladium complexes: synthesis, characterization and application as catalysts for Suzuki–Miyaura, Sonogashira, Heck and Hiyama reactions

A series of new non-phosphine 1-(2-picolyl)-3-benzoylsubstituted-2-benzyl-2-thiopseudourea ligands 2a–2f have been synthesized in two steps from commercially available benzoyl chlorides. Treatment of these ligands with Pd(OAc)2 in a 1 : 1 molar ratio in dichloromethane (DCM) at room temperature provided convenient access to the corresponding N,N,O-tridentate palladium(II) complexes [Pd(OAc){ArCONHC(N(CH2Py)}SCH2C6H5] (Ar = C6H5 (3a); 4-F-C6H4 (3b); 4-Br-C6H4 (3c); 4-I-C6H4 (3d); 4-Me-C6H4 (3e); 3,4,5-(OMe)3-C6H2 (3f)) in almost quantitative yields. The new ligands and their palladium complexes were characterized by NMR, IR, ESIMS, and HRMS analysis. The molecular structure of complex 3c has been determined by X-ray single-crystal diffraction. These Pd(II) complexes have been used as catalysts for the Suzuki–Miyaura, Sonogashira, Heck and Hiyama cross-coupling reactions.

“On water” catalysis: an expeditious approach for the synthesis of quaternary centered 3-hydroxy-3-(nitromethyl)indolin-2-one derivatives

A novel, efficient, eco-friendly “on water” method has been developed for the Henry reaction of isatins with nitromethane to afford 3-hydroxy-3-nitromethylindolin-2-ones. An enhancement in reaction rate was observed “on water” under mild and catalyst-free conditions. This reaction tolerated a wide range of substrates with good to excellent product yields and is even applicable at large scales. Moreover, this method is environmentally friendly as it reduces the waste generated by the use of toxic solvents.

“On water” one-pot synthesis of quaternary centered 3-hydroxy-3-(1H-tetrazol-5-yl)indolin-2-ones

An efficient green protocol has been developed for the synthesis of 3-hydroxy-3-(1H-tetrazol-5-yl)indolin-2-ones and 3-(phenylamino)-3-(1H-tetrazol-5-yl)indolin-2-ones as a novel class of oxindole derivatives by metal-free azide-nitrile [2 + 3] cycloaddition with excellent yields.

Identification of a New Potyvirus Associated with Chlorotic Vein Banding Disease of Spathiphyllum spp., in Andhra Pradesh, India

The genome of a potyvirus isolate associated with chlorotic spots and vein banding symptoms on Spathiphyllum spp., in Andhra Pradesh state, India was amplified by RT-PCR using degenerate potyvirus primers, amplicons cloned, and sequence (1.6 kb) analyzed. This virus isolate shared maximum identity of 74.8% and 80.2% at coat protein (CP) gene nucleotide (906 nucleotides) and amino acid (302 amino acids) levels, respectively with Dasheen mosaic virus (DsMV)-M13 isolate reported from China. But its 3`-UTR (258 nucleotides) had maximum identity of 62.5% with DsMV-Vietnam isolate. The deduced molecular weight of CP is 33.57 kDa and it contained DAG triplet in its N-terminal region. In CP amino acid based phylogenetic analysis, this virus isolate represented a separate branch but closer to DsMV isolates cluster. Based on the molecular criteria set for the discrimination of species and genus in the Potyviridae family, the present virus isolate was identified as a distinct virus species in the genus Potyvirus and proposed the name Spathiphyllum chlorotic vein banding virus (SCVbV).