D. Kishore

Synthetic Strategies Applicable in the Synthesis of Privileged Scaffold: 1,4-Benzodiazepine

Abstract The development of new synthetic approaches to the 1,4-benzodiazepine ring system and their further elaboration have provided access to a broad range of functionalized derivatives. In this review an attempt has been made to summarize those synthetic strategies involved for the synthesis of privileged scaffold 1,4-benzodiazepine over time. GRAPHICAL ABSTRACT

Transition metal-free one-pot synthesis of nitrogen-containing heterocycles

One-pot heterocyclic synthesis is an exciting research area as it can open routes for the development of otherwise complex transformations in organic synthesis. Heterocyclic compounds show wide spectrum of applications in medicinal chemistry, chemical biology, and materials science. These heterocycles can be generated very efficiently through highly economical and viable routes using one-pot synthesis. In particular, the metal-free one-pot synthetic protocols are highly fascinating due to several advantages for the industrial production of heterocyclic frameworks. This comprehensive review is devoted to the transition metal-free one-pot synthesis of nitrogen-containing heterocycles from the period 2010–2013.Graphical abstract

Noteworthy Mechanistic Precedence in the Exclusive Formation of One Regioisomer in the Beckmann Rearrangement of Ketoximes of 4-Piperidones Annulated to Pyrazolo-indole Nucleus by Organocatalyst Derived from TCT and DMF

Abstract Application of a very mild protocol to the Beckmann rearrangement of ketoximes of pyrazolo annulated oxocarbazole 5a and oxoazacarbazole 5b with the organocatalyst derived from 2,4,6-trichloro[1,3,5]triazine (TCT) and dimethylformamide (DMF) has been explored to provide a regioselective formation of the corresponding azepine 6a and 1,4-diazepine 6b respectively in good yield and purity. The mechanistic precedence for the exclusive formation of only one regioisomer has been discussed. GRAPHICAL ABSTRACT

Peroxy Acids: Role in Organic Synthesis

Abstract Peroxy acids are synthetically versatile reagents used in organic synthesis during recent years. This review describes the applications of peroxy acids for the generation of a range of structurally diverse organic compounds. GRAPHICAL ABSTRACT

An insight into hexamethylenetetramine: a versatile reagent in organic synthesis

Hexamethylenetetramine is a versatile reagent in organic synthesis. It plays a major role in modern organic synthesis. This review focuses on hexamine reagent for its significant role in organic synthesis during the past decades and is able to provide a valuable perspective from synthetic point of view.

An Expedient Protocol to the Synthesis of Benzo(b)furans by Palladium Induced Heterocyclization of Corresponding 2-Allylphenols Containing Electron Rich and Electron Capturing Substituents in the Arene Ring

A facile and rapid accessibility to the libraries containing several mono, and disubstituted benzo(b)furan derivatives substituted with a variety of electron rich and electron capturing groups on 2, 4, 5, 6, and 7 positions of its nucleus has been explored using the PdCl2(CH3CN)2 catalyzed heterocyclization of the corresponding 2-allylphenols to afford 2(a–m) in good yield and high purity.

Application of chalcones in heterocycles synthesis: Synthesis of 2-(isoxazolo, pyrazolo and pyrimido) substituted analogues of 1,4-benzodiazepin-5-carboxamides linked through an oxyphenyl bridge

AbstractVersatility of chalcone derivative of 2-(4′-acetyl)-phenoxyl-5-carboxamido-1,4-benzodiazepin-5-(4′-methylpiperazinyl)-carboxamide (6) was explored to provide an easy one-pot access to its 2-(isoxazolo, pyrazolo and pyrimido) substituted analogues 9, 10, 11, 12, 13, 14, 15, and 16. Graphical AbstractAn efficient novel strategy for the hetero-annulation of 2-chloro-1,4-benzodiazepine ring, substituted on its 5-position with a carboxamido group, has been developed to allow the incorporation of isoxazole, pyrazole and pyrimidine rings through their chalcone intermediate.

η6-Arenetricarbonylchromium(0) Complexes in the Synthesis of 1,4-Benzodiazepines and Its Nucleophilic Substituted Products

Abstract 7-Chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepines and its nucleophilic substituted products were synthesized via η6-arenetricarbonylchromium(0) intermediates. Ring enlargement of 5-chloro-N-chloroacetylisatin with hexamine in presence of Cr(CO)6 led to the formation of 7-chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepine in good yield with reduced reaction time. Nucleophilic substitutions on arene ring of η6-arenetricarbonylchromium(0) complexes with thiols, phenol, and primary amines were successfully carried out in decalin medium.

Solid-Phase Synthesis of Nitrogen-Containing Five-Membered Heterocycles

Abstract In recent decades, a large number of reports related to solid-phase synthesis of heterocycles have appeared, owing to the wide variety of their biological activity. This review introduces the key concepts of solid-phase methodology and combinatorial synthesis with particular focus on the important role of solid-phase synthesis in the synthesis of nitrogen-containing five-membered ring heterocycles. GRAPHICAL ABSTRACT

Use of 2,4,6-trichloro-1,3,5-triazine (TCT) as organic catalyst in organic synthesis

ABSTRACT Organic catalysts have found wide applications in organic synthesis. Many organic reactions, which originally do not occur under normal conditions or are difficult to operate normally, have been successfully conducted under mild conditions in the presence of catalysts. In recent years, 2,4,6-trichloro-1,3,5-triazine (TCT, cyanuric chloride) has been used as organic catalyst in many organic synthesis, because it is stable, nonvolatile, inexpensive, commercially available, and easy to handle. On account of these properties it has been used as a green catalyst and sometimes is a catalyst of choice in organic reactions. GRAPHICAL ABSTRACT