Rajarshi Samanta

Organocatalytic, Oxidative, Intermolecular Amination and Hydrazination of Simple Arenes at Ambient Temperature

New atom-economical, environmental friendly, direct oxidative intermolecular processes of amination and hydrazination of nonprefunctionalized arenes were developed. The products were formed in a good regioselective manner under organocatalytic conditions at ambient temperature.

Rhodium(III)-Catalyzed Direct Regioselective Synthesis of 7-Substituted Indoles

An efficient, atom-economic one-pot method was developed for the preparation of 7-substituted indoles via rhodium(III)-catalyzed oxidative cross-coupling. Regioselective olefination of indoline derivatives followed by one-pot subsequent oxidation provided the desired products in good to excellent yields.

C6-Selective Direct Alkylation of Pyridones with Diazo Compounds under Rh(III)-Catalyzed Mild Conditions.

A Rh(III)-catalyzed highly efficient C6-alkylation of 2-pyridones has been achieved successfully with α-diazo carbonyl compounds. The developed method is simple, mild, and highly regioselective with a broad range of substrate scope. The regioselectivity is guided by the pyridyl substituent attached to the nitrogen center of the pyridone ring. The directing group can be easily removed, and the only formed byproduct is nitrogen. Furthermore, other similar heterocyclic scaffolds can also be functionalized regioselectively under the developed conditions.

Rhodium(III)-Catalyzed C6-Selective Arylation of 2-Pyridones and Related Heterocycles Using Quinone Diazides: Syntheses of Heteroarylated Phenols

An efficient, direct C6-arylation of 2-pyridones has been successfully accomplished with quinone diazides under Rh(III)-catalyzed redox-neutral conditions. The optimized method is simple, mild, and highly regioselective with a broad substrate scope. The strict regioselectivity is guided by the pyridyl substituent attached to the nitrogen of the pyridone ring. As the directing 2-pyridyl group can easily be removed at any suitable stage after functionalization, the method provides a facile access to complex heteroarylated phenol moieties by wide-ranging heterocyclic scaffolds.

Rhodium(III)-Catalyzed Direct Oxidative Cross Coupling at the C5 Position of Chromones with Alkenes

An atom-economical, Rh(III)-catalyzed, direct oxidative cross-coupling at the C5 position of chromones and flavones with a broad range of alkenes was developed. The products were formed in a highly regioselective manner in good to excellent yields. The developed method was applied in the cross-coupling of natural products for the synthesis of hybrid molecules.

Copper Catalyzed Regioselective Cascade Alkylation and Cyclocondensation of Quinoline N-Oxides with Diazo esters:Direct Access to conjugated π-Systems

An inexpensive copper-catalyzed cascade regioselective alkylation, followed by cyclocondensation of quinoline N-oxides with α-diazo esters has been achieved successfully to provide heteroarene-containing conjugated π-systems. The developed method is simple, straightforward, and economical with a broad range of substrate scope. The dual role of copper catalyst in the C-H bond functionalization and in Lewis acid-promoted cyclization was explored.

Oxidative regioselective amination of chromones exposes potent inhibitors of the hedgehog signaling pathway

A transition metal-free, oxidative, regioselective cross-coupling between non-functionalized azoles and chromones at C2-position was developed. A broad reaction scope and further transformation of products were demonstrated. The biological evaluation of products revealed a novel class of hedgehog signaling pathway inhibitors.

Copper-Catalyzed Direct, Regioselective Arylamination of N-Oxides: Studies To Access Conjugated π-Systems

An efficient copper(I)-catalyzed direct regioselective arylamination of various heterocyclic N-oxides was achieved successfully under redox-neutral conditions using anthranils as arylaminating reagents. The developed protocol is simple, straightforward, and economic with a broad range substrate scope. The dual functional groups in the final molecules were utilized to construct structurally and functionally diverse nitrogen-containing organic π-conjugated systems.

A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from Pyridones: Application in the Detection of Nitroaromatics

A rhodium catalyzed direct regioselective oxidative annulation by double C-H activation is described to synthesize highly substituted quinolones from pyridones. The reaction proceeds at mild conditions with broad scope and wide functional group tolerance. These novel quinolones were explored to recognize nitroaromatic compounds.

A 1 : 2 copper(II)-tripeptide complex for DNA binding and cleavage agent under physiological conditions.

A 1 : 2 copper-tripeptide complex, [Cu(II)(Boc-His-Gly-His-OMe)(2)](2+), was synthesized and structurally characterized. The absorption band at 577 nm suggests a square-planar geometry around Cu(II). The DNA-binding and DNA-cleavage properties of the Cu(II) complex were investigated. The complex binds to calf thymus DNA (CT DNA) in an intercalative fashion and cleaves plasmid pUC-19 DNA hydrolytically at micromolar concentrations under physiological conditions. The intrinsic binding constant (K(b)=1.2x10(2) M(-1)) for the binding of Cu-tripeptide complex with DNA suggests that this complex is suitable for rapid diffusion on the pharmacological time scale.