4-Chloro-3-formylcoumarin as a multifaceted building block for the development of various bio-active substituted and fused coumarin heterocycles: a brief review

This review presents the diverse synthesis of 3,4-substituted coumarins and 5-, 6- and 7-membered ring fused coumarins using 4-chloro-3-formylcoumarin as the precursor via classical reactions including metal-catalyzed and green reaction protocols.

Cascade Reaction of 1,1-Enediamines with 2-Benzylidene-1H-indene-1,3(2H)-diones: Selective Synthesis of Indenodihydropyridine and Indenopyridine Compounds

A concise and environmentally friendly route for the synthesis of diverse indenodihydropyridines (3) via a cascade reaction of 1,1-eneamines (1) with benzylidene-1H-indene-1,3(2H)-diones (BIDs) (2) in ethanol media was developed. The targeted compounds were efficiently obtained by only filtration without any further post-treatment. In the one-step cascade reaction, C-C and C-N bonds were constructed. In addition, when 1,4-dioxane was used as a solvent and the mixture of 1,1-eneamines (1) was refluxed with benzylidene-1H-indene-1,3(2H)-diones (BIDs) (2) for about 12 h, indenopyridine compounds (4) were produced. Two kinds of indenopyridine derivatives 3-4 resulted from alternative solvents and temperatures. The reaction had the following features: mild temperature, atom economy, high yields, and potential biological activity of the product.

Facile Route to the Synthesis of 1,3-Diazahetero-Cycle-Fused [1,2-a]Quinoline Derivatives via Cascade Reactions

A one-step protocol without transition-metal catalysts with simple post-treatment for the synthesis of 1,3-diazaheterocycle-fused [1,2-a]quinoline derivatives via the cascade reaction of 2-fluorobenzaldehyde (1) and heterocyclic ketene aminals (2) was developed. In the one-step cascade reaction, C=C and C-N bonds were constructed, and the targeted compound can be efficiently obtained by filtering without column chromatography. This protocol describes a valuable route to concisely and feasibly obtain 1,3-diazaheterocycle-fused [1,2-a]quinoline derivatives. The synthetic methodology is particularly attractive because of the following features: low-cost solvent, mild temperature, atom economy, high yield, and potential biological activity of the product.

Diastereoselective Synthesis of Morphan Derivatives by Michael and Hetero-Michael Addition of 1,1-Enediamines to Quinone Monoketals

A general and concise method was developed for the synthesis of highly functionalized morphans 3-4 by the Michael and hetero-Michael addition reaction of different types of quinone monoketals 1 and 1,1-enediamines 2 in ethanol or 1,4-dioxane at reflux. This method is suitable for the efficient parallel syntheses of N-containing heterocycles. A library of highly functional morphan derivatives was easily constructed using the Michael/hetero-Michael reaction.

Synthesis and evaluation of the antitumor activity of highly functionalised pyridin-2-ones and pyrimidin-4-ones

The methods for selective synthesis of two novel types of compounds including pyridin-2-ones 3 and pyrimidin-4-ones 4 were developed. The antitumor bioactivity screening showed that certain compounds had potent antitumor activity.

Synthesis of bicyclic 2-pyridones by regioselective annulations of heterocyclic ketene aminals with anhydrides

An efficient strategy for the synthesis of substituted bicyclic 2-pyridones is developed. The proposed approach is based on the regioselective N-acylation of heterocyclic ketene aminals (HKAs) with methacrylic anhydride or crotonic anhydride.

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity.

Regioselective synthesis of pyrrolo[1,2-a]imidazoles and imidazo[1,2-a]-pyridines

A concise synthesis of pyrrolo[1,2-a]imidazoles and imidazo[1,2-a]-pyridines by regioselective aza-ene additions and regioselective cyclic–condensation reactions of HKAs with ethyl 3-benzoylacrylate derivatives under catalyst-free conditions.

Catalyst-free cascade reaction of heterocyclic ketene aminals with N-substituted maleimide to synthesise bicyclic pyrrolidinone derivatives

An efficient synthesis of bicyclic pyrrolidinones via a cascade reaction of HKAs and N-substituted maleimide in an environmentally friendly medium is described. This protocol uses group-assisted purification (GAP) chemistry. The library of bicyclic pyrrolidinone derivatives has been constructed with moderate to excellent yields.