Transition-Metal-Free Coupling Annulation of Arynes with Ketones and Alkynoates: Assembly of Functionalized Naphthalenes.

A transition-metal-free coupling annulation reaction of arynes, ketones, and alkynoates has been demonstrated. Using this formal [2 + 2 + 2] cycloaddition reaction, a wide variety of naphthalene derivatives were conveniently constructed in one pot with high efficiency. In addition, this novel and valid annulation has been successfully applied to the synthesis of 1-phenanthrenol derivatives.

Acid-Mediated N-H/α,ß-C(sp(3))-H Trifunctionalization of Pyrrolidine: Intermolecular [3 + 2] Cycloaddition for the Construction of 2,3-Dihydro-1H-Pyrrolizine Derivatives.

A one-pot acid-mediated reaction has been developed for the N-H/α,ß-C(sp(3))-H trifunctionalization of pyrrolidine without any metallic reagents or external oxidants. This reaction involves the intermolecular [3 + 2] cycloaddition of in situ-generated azomethine ylides with acrylic esters to provide facile access to 2,3-dihydro-1H-pyrrolizine derivatives in high yields under mild conditions.

Multicomponent Coupling Cyclization Access to Cinnolines via in Situ Generated Diazene with Arynes, and α-Bromo Ketones.

A transition-metal-free multicomponent coupling cyclization reaction was explored involving arynes, tosylhydrazine, and α-bromo ketones. The reaction proceeds via a formal [2 + 2 + 2] cycloaddition, giving access to cinnoline derivatives in moderate yields under mild conditions. Three chemical bonds were formed-two C-N bonds and one C-C bond-in a single step.

Transition-Metal-Free Multicomponent Benzannulation Reactions for the Construction of Polysubstituted Benzene Derivatives.

A transition-metal-free multicomponent benzannulation reaction was developed from readily available ketones, nitro-olefins, and diester acetylenedicarboxylate. This approach provides a straightforward and efficient way to construct polysubstituted benzene derivatives under mild conditions in high yields.

Convenient access to polyfunctional pyrazoles via a highly efficient and regioselective multicomponent reaction.

A multicomponent reaction has been developed for the synthesis of polyfunctional pyrazole derivatives from readily available arylglyoxal monohydrates, tosylhydrazine, and aldehydes or ketones. This synthetic method has significant advantages in broad substrate scope, excellent regioselectivity, and simple operation.

Efficient approach to 2-hydroxy-2,3-dihydrofuran derivatives and its application for the synthesis of novel 4-(1H-pyrazol-4-yl)pyridazines.

A highly efficient method for the synthesis of 2-hydroxy-2,3-dihydrofuran derivatives from 1,4-enediones and phenacyl pyridinium halides via a domino reaction has been developed. This is a simple and beneficial strategy for the construction of 2-hydroxy-2,3-dihydrofuran compounds from readily available starting materials under mild conditions. Moreover, the application of this reaction provides a straightforward and practical route for the synthesis of the novel 4-(1H-pyrazol-4-yl)pyridazine skeleton.

Brønsted acid promoted addition-cyclization and C-C bond cleavage: a convenient synthesis of 2-amino-5-aroylmethylthiazoles derivatives.

A Brønsted acid promoted C-C bond cleavage method for the synthesis of novel 2-amino-5-aroylmethylthiazole derivatives has been directly developed from 1,4-enediones and thioureas through self-sequenced thio-Michael-addition, intramolecular selective cyclization, dehydration/aromatization, and C-C bond cleavage reactions. It is noteworthy that this reaction has significant advantages in simple reagents, under environmentally benign conditions and with excellent yields. This highly efficient method is also a highly attractive alternative for the preparation of PLTP, CETP inhibitors and novel biheterocycles.

An efficient synthesis of novel fused cycloheptatrienes through Mn(II)-mediated formal intermolecular [2 + 2 + 2 + 1] cycloaddition.

A new method for manganous acetate tetrahydrate mediated formal intermolecular [2 + 2 + 2 + 1] cycloaddition was developed for the synthesis of fused cycloheptatriene derivatives from N-(acylmethyl)pyridinium iodides and naphthoquinone. This method provides an innovative route for the efficient and convenient construction of fused seven-membered carbocycles from simple starting materials.