The Study On The Synthesis Of Heterocyclic Compounds Such As Pyrans And Phthalazines Derivatives By Multi-component "One-pot" Reaction

In recent years,multi-component reactions（MCRs）as effective synthesis methodology have attracted much attention in combinatorial and medicinal chemistry owing to good atom economy,and high product yield,as well as being energy saving,and it is also used in synthesis of biologically active heterocyclic rings compounds.Pyrans and phthalazines compounds have a wide range of biological and pharmacological activities,and they are present in many natural products.Therefore,the multi-component catalytic synthesis of these two kinds of compounds have received extensive attention from researchers.Based on the multi-component reactions system,this paper studies the efficient,simple and green synthesis of pyrans and phthalazines derivatives,optimizes and expands the catalytic system.The details are as follows:1.A convenient one-pot multi-component strategy was conducted successfully under catalyst-free condition employing the mixture of water and ethanol as the efficient and cheap promoting medium.Two kinds,36 2-amino-3-cyano-4H-pyran annulated derivatives were synthesized in good to excellent yields by the condensation of a series of aldehydes with malononitrile and dimedone/1,3-cyclohexanedione.Then the optimum reaction conditions were adjusted.The reaction system was extended to the three-component reaction of aldehydes,malononitrile and 4-hydroxycoumarin to synthesize 17 benzopyran derivatives.Broad substrate scope,systematic characterization,eliminated catalyst,mild reaction condition,and simple purification procedure are the best advantages in this methodology.The structure of the all of the products were characterized by IR,¹H NMR and ¹³C NMR.2.The synthesis of 16 phthalazines derivatives using dipotassium hydrogen phosphate trihydrate（K₂HPO₄·3H₂O）as a cheap and readily available catalyst was described.Good to excellent yields were obtained via three-component condensation of phthalhydrazide,malononitrile,and aromatic aldehydes in mixture solvent of water and ethanol.This approach provides some features such as using green catalyst,mild reaction conditions,and the products don’t require additional purification to obtain a pure compound.Part target compounds were characterized by IR,¹H NMR,and ¹³C NMR.