Synthesis Of Benzopyrano Research Articles

TiO2–SiO2 Catalyzed Eco‐friendly Synthesis and Antioxidant Activity of Benzopyrano[2,3‐d]pyrimidine Derivatives

A cost‐effective and eco‐friendly synthesis of benzopyrano[2,3‐d]pyrimidine derivatives has been developed via three component one‐pot tandem approach by condensing different salicylaldehydes and secondary amines with malononitrile in the presence of TiO2–SiO2 catalyst at 80°C under solvent‐free conditions. Mild experimental conditions, reusability of the catalyst, and cost effectiveness are the merits of this procedure. Compounds 4g, 4h, and 4i bearing 2‐OMe group on the hydroxyphenyl group linked to the central carbon present in between the two nitrogen atoms of the pyrimidine ring were found to exhibit good antioxidant activity while other compounds have moderate antioxidant activity.

Synthesis of New Benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins From 3-cyano Iminocoumarin Derivatives

Synthesis of benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins was successfully performed using heterocyclization of 3-cyano iminocoumarin or their N-ethoxycarbonylated derivatives with semicarbazide reagents. Elemental analysis, infrared, and 1H NMR spectral data confirmed the molecular structure of the newly synthesized compounds.

One‐Pot Microwave‐Assisted Synthesis of Benzopyrano[2,3‐c]pyrazol‐3‐one Derivatives

A convenient one‐pot microwave‐assisted synthesis of Benzopyrano[2,3‐c]pyrazol‐3‐one derivatives was developed, where Knoevenagel condensation and hydrazinolysis reactions were continuously performed under microwave irradiation without separation and purification of the intermediates until the last cyclocondensation reaction except the substrates addition. The one‐pot procedure exhibited shorter reaction times and higher yields (25–55%) of the objects than the conventional heating method.

Catalytic Method for Synthesis of Benzopyrano[3,2-c]chromene-6,8-dione Derivatives by Heteropoly Acids

Benzopyrano[3,2-c]chromene-6,8-dione derivatives were prepared by a three-component one-pot cyclocondensation of 4-hyroxycoumarin, aldehydes, and 1,3,cyclohexadione using a catalytic amount of heteropolyacids in boiling ethanol in very good yields and rates.

Efficient Methods for the Synthesis of Benzopyrano[3,4-c]pyrrolidines by Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with 3-Substituted Coumarins

With triethylamine as a catalyst, the 1,3-dipolar cycloaddition of azomethine ylides with 3-substituted coumarins proceeded smoothly under mild conditions to afford the desired products benzopyrano[3,4-c]pyrrolidines in good to excellent yields.

Parallel Liquid‐Phase Synthesis of Benzopyrano[2,3‐d]pyrimidine Libraries.

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