This chapter will emphasize the recent advancements focusing on (i) transition-metal-based organic transformations of 1,2,3-benzotriazin-4(3 H)-ones, (ii) reactions of 1,2,3-benzotriazin-4(3 H)-ones under thermal and photolytic conditions, as well as (iii) acid mediated or metal-free reactions of 1,2,3-benzotriazin-4(3 H)-ones to fabricate highly functionalized five, six-membered N-heterocycles and ortho -functionalized benzamides. Further, this book chapter also discusses the denitrogenative reactions of 1,2,3,4-benzothiatriazine-1,1(2 H)-dioxides with suitable reaction mechanisms of the developed protocols.

An efficient metal-free approach for synthesizing N-aryl- and N-alkyl phthalimide derivatives from 1,2,3-benzotriazin-4(3H)-ones is described. The reaction likely proceeds via a denitrogenative cyanation pathway, utilizing TMSCN as the cyanide source. This method is straightforward as well as scalable and supports a wide range of substrates with high functional group tolerance, yielding diverse phthalimide derivatives in good to excellent yields. The utility of this method is further highlighted by the successful synthesis of a tyrosinase inhibitor analogue in good yield

A novel approach for the synthesis of diverse substituted imidazoles and quinoxalines via an iodine-promoted cyclization reaction is described. The methodology showcases a broad substrate scope, achieving moderate to very good yields for biologically relevant imidazoles and quinoxalines. Notably, iodine serves as both an iodinating agent and an oxidizing agent, as shown by a mechanistic study. The current methodology is capable of being scaled up to gram quantities, operates in a metal-free environment under mild reaction conditions, and utilizes readily available substrates

An efficient construction of C?N and C?O bonds by the metal?free organophotoredox catalyzed intramolecular cross?dehydrogenative coupling of tertiary amines with amides, amines, and acids as nucleophiles is described. A series of 12,13?dihydro?6H?isoquinolino[2,1?a]quinazolin?6?one, 5,6?dihydrobenzo[4,5]imidazo [2,1?a]isoquinoline, and 4b,13?dihydro?6H,12H?benzo[4,5] [1,3]oxazino[2,3?a]isoquinolin?6?one derivatives were prepared in good to excellent yields. All the transformations proceeded smoothly under an oxygen atmosphere, serving as a clean oxidant. Moreover, the current approach was extended for the synthesis of the biologically active natural product, rutaecarpine.

An efficient and straightforward approach to synthesize salicylanilide aryl and alkyl sulfonates from 1,2,3-benzotriazin-4(3H)-ones and organosulfonic acids is described. This protocol is operationally simple and scalable, exhibits a broad substrate scope with high functional group tolerance, and affords the desired products in good to high yield. Application of the reaction is also demonstrated by converting the desired product to synthetically useful salicylamides in high yields.

An efficient trifluoroacetic acid-mediated denitrogenative hydroxylation of 1,2,3-benzotriazin-4(3H)-ones is described. This metal-free approach is compatible with a wide range of 1,2,3-benzotriazin-4(3H)-ones, affording ortho-hydroxylated benzamides in good to high yields with a short reaction time. The reaction is believed to proceed via a benzene diazonium intermediate. The synthetic utility of the reaction was successfully demonstrated by the preparation of an antimicrobial drug, Riparin C, and benzoxazine-2,4(3H)-diones in good yields.

Metal nanoparticles grafted within inert and porous wide-area supports are emerging as recyclable, sustainable catalysts for modern industry applications. Here, we bioengineered gold nanoparticle-based supported catalysts by utilizing the innate metal binding and reductive potential of eggshell as a sustainable strategy. Variable hand-recyclable wide-area three-dimensional catalysts between ?80 ± 7 and 0.5 ± 0.1 cm2 are generated simply by controlling the size of the support. The catalyst possessed high-temperature stability (300 °C) and compatibility toward polar and nonpolar solvents, electrolytes, acids, and bases facilitating ultra-efficient catalysis of accordingly suspended substrates. Validation was done by large-volume (2.8 liters) dye detoxification, gram-scale hydrogenation of nitroarene, and the synthesis of propargylamine. Moreover, persistent recyclability, monitoring of reaction kinetics, and product intermediates are possible due to physical retrievability and interchangeability of the catalyst. Finally, the bionature of the support permits ?76.9 ± 8% recovery of noble gold simply by immersing in a royal solution. Our naturally created, low-cost, scalable, hand-recyclable, and resilient supported mega-catalyst dwarfs most challenges for large-scale metal-based heterogeneous catalysis.

Herein, we report the synthesis and application of a Zn-Bp-BTC MOF (Bp-4,4?-bipyridine; BTC-1,3,5-benzene tricarboxylic acid; MOF-metal organic framework) as a heterogeneous catalyst for mediating organic reactions. Initially, conditions were optimized for the Knoevenagel condensation reaction using Zn-Bp-BTC as a heterogeneous catalyst by varying the solvent, temperature and catalyst loading. Although the reaction proceeded at room temperature using methanol as the solvent, 60 °C offered the best yield in a shorter duration. Under optimized reaction conditions, a wide range of ?,?-unsaturated dicyano compounds were prepared from the corresponding carbonyl precursor and malononitrile, the active methylene counterpart. Systematic investigation was also carried out to assess the role of the ligand and metal salt in the Knoevenagel condensation reaction. It was found that the Zn-Bp-BTC MOF catalyzed the reaction efficiently in comparison to its analogue Zn-BTC MOF and precursor Zn(NO)·6HO. Finally, catalytic recycling and stability studies showed that the catalyst is able to mediate the reaction for up to five consecutive cycles without undergoing any significant chemical or morphological changes. Further, the catalyst was tested for its efficacy in a multi-component reaction (MCR). A MCR with the Zn-Bp-BTC MOF as the catalyst afforded good yields and there was no reaction in the absence of the catalyst. Similarly, the catalyst was tested for its efficiency in benzimidazole synthesis.

A novel nickel-catalyzed approach to synthesize ortho-arylated and alkenylated benzamides in good to high yields via a denitrogenative cross-coupling reaction of 1,2,3-benzotriazin-4(3H)-ones with organoboronic acids is described. The reaction proceeds through a five-membered azanickelacyclic intermediate with the extrusion of a nitrogen molecule. Moreover, the resulting ortho-arylated benzamides were successfully converted into synthetically useful substituted fluorenones and ortho-arylated benzylamine derivatives in high yields.