Krishna Nand Singh

A Direct Metal-Free Decarboxylative Sulfono Functionalization (DSF) of Cinnamic Acids to α,β-Unsaturated Phenyl Sulfones

A metal-free room temperature decarboxylative cross-coupling between cinnamic acids and arylsulfonyl hydrazides has been realized for the first time for the synthesis of (E)-vinyl sulfones. The scope and versatility of the reaction has been demonstrated by the regio- and stereoselective synthesis of 22 derivatives with diverse structural features.

Regioselective Hydrothiolation of Alkynes by Sulfonyl Hydrazides Using Organic Ionic Base–Brønsted Acid

A practical and novel approach has been developed for the synthesis of vinyl sulfides by the reaction of sulfonyl hydrazides with aryl/heteroarylacetylenes using a DBU-based ionic liquid. The system offers a new sulfur source for hydrothiolation and is endowed with green credentials.

Nickel-Mediated N-Arylation with Arylboronic Acids: An Avenue to Chan–Lam Coupling

An efficient use of NiCl(2)·6H(2)O, for the cross-coupling of arylboronic acids with various N-nucleophiles, has been demonstrated. The method is practical and offers an alternative to the corresponding Cu-mediated Chan-Lam process for the construction of the C-N bond.

MnO2 Promoted Sequential C–O and C–N Bond Formation via C–H Activation of Methylarenes: A New Approach to Amides

A novel and efficient approach for the synthesis of amides has been developed through manganese dioxide promoted nondirected C-H activation of methylarenes under mild reaction conditions employing N-chloroamines as effective coupling partners.

Convenient MW-assisted synthesis of unsymmetrical sulfides using sulfonyl hydrazides as aryl thiol surrogate.

An efficient synthesis of unsymmetrical sulfides has been achieved via the cross-coupling reaction of aryl/het-aryl/benzyl halides with stable and easily workable sulfonyl hydrazides as thiol substitutes by means of [DBU][HOAc] and CuI under microwave irradiation.

Decarboxylative Thioamidation of Arylacetic and Cinnamic Acids: A New Approach to Thioamides

A new decarboxylative strategy has been developed for the synthesis of thioamides via a three-component reaction involving arylacetic or cinnamic acids, amines and elemental sulfur powder, without the need of a transition metal and an external oxidant.

Hypervalent iodine catalyzed transamidation of carboxamides with amines

This protocol describes the catalytic use of diacetoxyiodobenzene (DIB) for the efficient transamidation of carboxamides with amines under mild conditions.

Elemental Sulfur Mediated Decarboxylative Redox Cyclization Reaction of o-Chloronitroarenes and Arylacetic Acids

A decarboxylative redox cyclization strategy has been developed for the synthesis of 2-substituted benzothiazoles by the reaction of o-chloronitroarenes and arylacetic acids in the presence of elemental sulfur/N-methylmorpholine under metal- and solvent-free conditions.

AIBN-initiated metal free amidation of aldehydes using N-chloroamines

An efficient and environmentally benign amidation of aldehydes with N-chloroamines has been developed using AIBN as an initiator. This methodology offers a metal free and base free approach and is endowed with mild reaction conditions, high yields, and good functional group tolerance.

A binuclear Mn(II) complex as an efficient catalyst for transamidation of carboxamides with amines

A binuclear Mn(II) complex has been synthesized and characterized by different structural methods. The complex contains two unique oxo-bridged metal centres and has been explored as an excellent catalyst for transamidation of carboxamides with amines under solvent-free conditions.