Tirumaleswararao Guntreddi

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.

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.

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.

Utilization of carbon disulfide as a powerful building block for the synthesis of 2-aminobenzoxazoles

This protocol describes a novel, mild and convenient route to afford 2-aminobenzoxazoles in high yields, and represents a significant advance towards an environmentally friendly strategy. Aliphatic amines are made to react with carbon disulfide to provide intermediate dithiocarbamates (DTC), which in the presence of 2-aminophenol, subsequently undergo successive intermolecular nucleophilic attack and desulfurization to produce 2-aminobenzoxazoles within 3 h.

A practical protocol for the synthesis of bibenzyls via C(sp3)–H activation of methyl arenes under metal-free conditions

A variety of bibenzyl derivatives have been synthesized with excellent atom economy via C(sp3)–H–C(sp3)–H coupling of readily available methyl arenes using K2S2O8 under metal-free and environmentally benign conditions.

Copper catalysed C–N bond formation via a sequential acylation and deacylation process: a novel strategy for the synthesis of benzanilides

An efficient and mild oxidative amidation of aldehydes by means of acetanilides as amine components has been developed for the first time using copper catalysis. The approach is versatile and proceeds through sequential acylation and deacylation steps to afford benzanilides.

Elemental sulfur mediated synthesis of benzoxazoles, benzothiazoles and quinoxalines via decarboxylative coupling of 2-hydroxy/mercapto/amino-anilines with cinnamic acids

An easy and practical method has been developed for the synthesis of 2-benzylbenzoxazoles and 2-benzylbenzothiazoles using sulfur mediated decarboxylative coupling of cinnamic acids with 2-hydroxyanilines and 2-mercaptoanilines respectively under metal- and solvent-free conditions. However, the reaction of 2-aminoanilines with cinnamic acids leads to the formation of 2-arylquinoxalines under the same set of reaction conditions. The transformation is versatile and compatible with a number of functional groups.

Palladium-Catalyzed Site-Selective C-H Functionalization of Weakly Coordinating Sulfonamides: Synthesis of Biaryl Sulfonamides.

A novel and site selective C-H functionalization of unsubstituted sulfonamides has been developed for the synthesis of ortho aryl sulfonamides. The reaction involves highly regioselective ortho mono arylation of weakly coordinating SO2 NH2 directing group by means of aryl iodides. Palladium acetate in the presence of silver(I) oxide is found to be the most effective catalytic system.

Transformable Sulfoximine Assisted One-Pot Double Annulation of Vinylic C–H Bonds with Unactivated Alkynes

The methylphenyl sulfoximine (MPS) directing group (DG) successfully promotes the one-pot double annulation of acrylic acids with alkynes under Ru catalysis, which is unprecedented. Diverse arrays of pyrido-fused-isoquinolinone skeletons are fabricated from acrylamides, creating two C-C and two C-N bonds in a single operation. The unsymmetrical annulation with two distinct alkynes is presented. The recovery of methylphenyl sulfoxide, a precursor of MPS, validates the synthetic adaptability of transformable-DG (TfDG) in C-H activation.