One Pot Synthesis of Novel Substituted 2',4'-Dihydrospiro[chroman-2,3'-pyrazol]-4-one Derivatives

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.