A facile and simple catalyst-free protocol has been developed for the condensation of 1,2-diketones with aromatic 1,2-diamines in polyethylene glycol (PEG), providing quinoxaline derivatives in good yields. The important features of the methodology are broad substrates scope, simple workup, catalyst free, environmentally benign, and no requirement for metal catalysts. It is noteworthy that the cyclization reaction of 1,2-diketones with aliphatic 1,2-diamines is also conducted smoothly to afford pyrazines in good yields under the standard conditions. In addition, PEG could be recovered easily and was reused without evident loss in activity

The first example of a palladium-catalyzed aerobic oxidative coupling of acyl chlorides with arylboronic acids has been developed, leading to a wide range of aryl benzoates in good to excellent yields. This catalytic system shows broad functional group tolerance. Preliminary mechanistic experiments using deuterium labeling showed that the oxygen atom was derived from dioxygen.

An efficient metal-free sulfenylation of indoles with disulfides has been developed, leading to 3-arylthioindoles in moderate to excellent yields. Furthermore, bromosulfenylation of indoles with disulfides has been realized for the first time providing a new family of 2-bromo-3-arylthioindole derivatives in good yield by the one-pot construction of CS and CBr bonds. It is noteworthy that the system enables the use of both the RS moieties in RSSR and shows a broad functional group tolerance.

An efficient and convenient copper-catalyzed Clauson–Kass reaction of 2,5-dimethoxytetrahydrofuran with amines in aqueous media has been developed, providing a wide range of N-substituted pyrroles in good yields. It is noteworthy that the Clauson–Kass reaction of 2,5-dimethoxytetrahydrofuran with p-phenylenediamine or m-phenylenediamine proceeds smoothly to afford the corresponding monopyrroles and bispyrroles with high selectivity in impressive yields. A plausible mechanism for the formation of N-substituted pyrroles has been proposed. Copyright © 2012 John Wiley & Sons, Ltd.

A highly practical method to access unsymmetrical and symmetrical thiosulfonates in moderate to excellent yields has been developed through NBS-promoted sulfenylation of sulfinates with disulfides. The present process enables the use of two RS in RSSR and shows broad functional group tolerance, which represents an atom-economical and practical procedure for the synthesis of thiosulfonates. A plausible mechanism for the role of NBS as a promoter for the cleavage of disul?des generating N-(organothio)succinimide that then undergos facile sulenylation with sulfinates is proposed.

Citric acid promoted synthesis of a mini-library 2,3-dihydroquinazolin-4(1H)-ones with good to excellent yields is achieved by tandem reaction of anthranilamides (or anthranilhydrazides) with aldehydes on grinding at room temperature under solvent-free conditions. This method has notable advantages in terms of simple workup, short reaction time, cost-effective, and environmentally benign. J. Heterocyclic Chem., (2012).

An efficient and facile synthesis of quinoxaline derivatives in excellent isolated yields by the condensation of 1,2-diamines and 1,2-diketones on grinding under solvent-free conditions at ambient temperature has been developed. The important features of this method are that it is reasonably fast, very clean, high yielding, simple workup, and environmentally benign. J. Heterocyclic Chem., 00, 00 (2011).

An efficient and convenient three-component A³ coupling reaction of aldehyde, amine and alkyne via CH activation with CuI alone as the catalyst in PEG is developed, providing a wide range of propargylamines with yields ranging from moderate to excellent. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2010 John Wiley & Sons, Ltd.

A palladium-catalyzed coupling-type reaction of arylglyoxals with arylboronic acids was achieved by use of trimesitylphosphine as the ligand and K₂CO₃ as base in toluene, providing symmetrical and unsymmetrical benzil derivatives with yields ranging from moderate to excellent. Of particular mention, the rigorous exclusion of air and moisture is not required in these transformations. Copyright © 2009 John Wiley & Sons, Ltd.