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An efficient and rapid method was developed for the synthesis of C3-pyranopyrazole-substituted coumarins from one-pot five-component reaction of β-keto ester, hydrazine, O-hydroxy aromatic aldehydes, 6-methyl, 4-hydroxy pyranone and aromatic aldehyde in the presence of tri-ethylamine in solvent-free conditions. The microwave-assisted method reported herein offers advantageous shorter reaction times, higher yields and cleaner reaction compared with conventional heating methods.

Aim and Objective: In the work, we have successfully presented a synthetic route for the synthesis of novel 2',4'-dihydrospiro[chroman-2,3'-pyrazol]-4-one derivatives via one pot multicomponent approach. Material and Method: Substituted 2',4'-dihydrospiro[chroman-2,3'-pyrazol]-4-one were prepared through cascade three-component condensation of ortho-hydroxyacetophenone, β-ketoester, hydrazine in the presence of pyrrolidine as a catalyst under ethanol reflux conditions. Results: A series of novel 2',4'-dihydrospiro[chroman-2,3'-pyrazol]-4-one have been synthesized through a facile strategy. These structures of newly synthesized derivatives were determined by 1H, 13C NMR, HRMS and CHNS analysis. Conclusion: We have achieved the one-pot, three-component synthesis of highly substituted pyrazole spirochromanones in presence of pyrrolidine as a catalyst under ethanol reflux conditions. Using different types of aliphatic and aromatic β-ketoesters, o-hydroxyacetophenone derivatives and different kinds of hydrazine derivatives as building blocks, we could construct novel libraries of substituted pyrazole spirochromanones that make this method suitable for combinatorial and parallel synthesis in drug discovery.

A facile synthesis of spirobiindane bis-coumarin hybrid molecules with C4-alkyl, C3-acyl, C3-ethoxycarbonyl or C3-nitrile groups has been achieved. Absorption, emission and solvatochromic characteristics of the bis-coumarins were evaluated in comparison with 3-acetylcoumarin. Studies show that the bis-coumarins with C3-ester and C3-cyano group show more than tenfold increase in fluorescence emission than others in hexane and ethyl acetate. Unlike in the cases of the bis-coumarins with an electron withdrawing acyl or ester group at C3 position where methanol quenches fluorescence emission there is no significant solvent effect in the case of an alkyl group at C4 position.

A facile synthesis of some spirobiindane based bis-flavanones and bis-chroman-4-ones was achieved by employing Kabbe reaction on spirobiindane bis-acetophenone as the key step.

A facile two step synthesis of 3-aroylcoumarin-flavone hybrids was achieved from 7-hydroxyflavone and - oxoketene dithioacetals. In the first step 7-hydroxyflavone was regioselectively formylated under Duff reaction conditions. Resulting 8-formyl-7-hydroxy flavones were condensed with -oxoketene dithioacetals in the presence of a catalytic amount of piperidine to furnish 3-aroylcoumarin-flavone hybrids.