An Unprecedented and Concise Method for the Synthesis of 1,3-Thiazino-[3,4a][1,3]benzimidazoles via a Three-Component Reaction

Abstract

For the first time, a novel, simple, and highly efficient synthesis of N-aryl-N-[1,3]thiazino [3,4a] [1,3]benzimidazol-1-ylidenamines is presented. The one-pot reaction of o-phenylenediamine, aryl isothiocyanate, and methyl acetylenecarboxylate proceeds in toluene-dichloromethane without any catalyst under reflux conditions to produce the title compounds in 60-70% yield. From a mechanistic point of view, the reaction is proposed to occur via two cyclizations and four heteroatom-carbon bond formations.

One-Pot, Pseudo Five-Component Synthesis of Spirooxindole Derivatives Containing Fused 1,4-Dihydropyridines in Water

“…In continuing efforts to develop new routes for the synthesis of biologically active heterocyclic compounds, [12][13][14][15][16][17][18] a five-component reaction that generates spirooxindole heterocycles is described herein. Thus, the reaction between 1,1-bis(methylthio)-2-nitroethylene, two equivalents of ammonia, isatin or its derivatives 1, and 1,3-dicarbonyl compounds 2 in the presence of 10 mol% p-toluenesulfonic acid (p-TSA) as an inexpensive catalyst in water under reflux conditions afforded a series of spirooxindole derivatives 3 containing 1,4-dihydropyridine-fused 1,3-diazaheterocycle fragments in 75-81% yields ( Table 1).…”

One‐pot synthesis of highly functionalized benzo [1,3] thiazine from isocyanides, aniline, and heterocumulene via Cu‐catalyzed intramolecular C‐H activation reactions

“…There are some reported methods for synthesis of benzothiazines in the literature but most of them have some disadvantages, for example low yields, use of hazardous organic solvents, strongly acidic conditions, tedious workup procedures, etc . Therefore, development of effective synthetic methods with acceptable protocols is still desirable.…”

“…There are some reported methods for synthesis of benzothiazines in the literature but most of them have some disadvantages, for example low yields, use of hazardous organic solvents, strongly acidic conditions, tedious workup procedures, etc. [9][10][11][12][13] Therefore, development of effective synthetic methods with acceptable protocols is still desirable. The ortho C-H functionalization of aromatic compound is of considerable current interest for the synthesis of heterocyclic compounds in the pharmaceutical industry.…”