Tetrabutylammonium chloride-triggered 6-endo cyclization of o-alkynylisocyanobenzenes: an efficient synthesis of 2-chloro-3-substituted quinolines

Bicyclic Amidine-Triggered Cyclization of o-Alkynylisocyanobenzenes: Synthesis of Lactam-Derived Quinolines

Efficient access to the synthesis of lactam-derived quinoline through a bicyclic amidine-triggered cyclization reaction from readily prepared o-alkynylisocyanobenzenes has been developed. The reaction was initiated by nucleophilic attack of the bicyclic amidines to o-alkynylisocyanobenzenes, subsequently with intramolecular cyclization to produce a DBU-quinoline-based amidinium salt, followed by hydrolysis to afford the lactam-derived quinoline in moderate to good yields.

Synthesis of 3-substituted quinolin-2(1H)-ones via the cyclization of o-alkynylisocyanobenzenes

A facile synthesis of various functionalized 3-substituted quinolin-2(1H)-ones through Ag(i) nitrate-catalyzed cyclization of o-alkynylisocyanobenzenes is described. The reaction allows rapid and convenient access to 3-substituted quinolin-2(1H)-one scaffolds in moderate to good yields.

Sulfinates and thiocyanates triggered 6-endocyclization ofo-alkynylisocyanobenzenes

An efficient synthesis of 2-sulfonyl- and 2-thiocyanato-3-substituted quinolines through sequential nucleophilic addition/cyclization ofo-alkynylisocyanobenzenes is described.

An Efficient One-Pot Synthesis of Densely Functionalized Fused-Quinolines via Sequential Ugi4CC and Acid-Mediated Povarov-Type Reaction

A divergent synthesis of fused-quinolines has been explored by performing Ugi four-component condensation and sulfuric acid promoted deprotection/Povarov-type reaction in one-pot. The process involves Ugi condensation of propiolic acids, aldehydes/ketones, aminoaldehyde acetals and isocyanides followed by sulfuric acid promoted deprotection and Povarov-type reaction with anilines in ethanol. This method enables straightforward access to the structurally diverse 2,3-dihydro-1H-pyrrolo[3,4-b]quinolin-1-ones (DHPQ), 3,4-dihydrobenzo[b][1,6]naphthyridin-1(2H)-ones (DHBN), and 2,3,4,5-tetrahydro-1H-azepino[4,3-b]quinolin-1-ones (THAQ), starting from readily available starting materials.

Synthesis of unsymmetrical phenylurea derivatives via oxidative cross coupling of aryl formamides with amines under metal-free conditions

A direct transformation of N-aryl formamides to the corresponding phenylurea derivatives via the formation of isocyanate intermediates is achieved in good yields using hypervalent iodine reagents as external oxidants.

A transition-metal-free synthesis of arylcarboxyamides from aryl diazonium salts and isocyanides

A transition-metal-free carboxyamidation process, using aryl diazonium tetrafluoroborates and isocyanides under mild conditions, has been developed. This novel conversion was initiated by a base and solvent induced aryl radical, followed by radical addition to isocyanide and single electron transfer (SET) oxidation, affording the corresponding arylcarboxyamide upon hydration of the nitrilium intermediate.

Synthesis of 2-boryl- and silylindoles by copper-catalyzed borylative and silylative cyclization of 2-alkenylaryl isocyanides

We have developed a method for the synthesis of 2-borylindoles via the copper(I)-catalyzed borylative cyclization of 2-alkenylphenyl isocyanides using diboronate. The reaction proceeds at room temperature under neutral conditions and exhibits high tolerance to functional groups, such as Br, CO(2)R, COR, CONMe(2), and CN. The 2-borylindoles synthesized in the present study can be elaborated into an array of indole-based derivatives, for example, through the Suzuki-Miyaura reaction. The utility of this method is demonstrated in the rapid synthesis of a kinase inhibitor, paullone. The reaction can be extended to the synthesis of 2-hydride indole and 2-silylindole by using hydroboronate (or hydrosilane) and silylboronate, respectively. Under these copper-catalyzed conditions, a quinoxaline ring system can also be constructed by using 1,2-isocyanobenzene as a substrate.