Studies On The Synthesis Of Thiochromones And 4-quinolones Derivatives

4H-Thiochromen-4-one can be regarded as the homologue of the core constituent of the natural product class of flavones.Such frameworks are frequently found in a diverse array of compounds,including natural products,and potent drug candidates as antibacterial,antitumor,antibiotic,antifungal,and anticarcinogenic agents.Some derivatives are used as antimalarials,and their oxidized products are reversibly inhibiting human cytomegalovirus proteases.The quinolin-4-one skeleton is usually present in a variety of compounds,including natural products,synthetic structural units and therapeutically active molecules such as antibacterials,antineoplastic agents,antimalarials,or anti-mitotic agents or HIV-1 integrase inhibitors agents.As a result,the construction of this valuable structural unit has received considerable attention and much effort has focused on the new and efficient development of synthetic methods.The classical synthetic pathway is based on a variety of ring condensation strategies,but the harsh reaction conditions significantly limit their scopes.The development of a milder process for the assembly of quinolin-4-one ring system is of great importance.In this paper,we set out to develop a new synthetic protocol for the construction of 4-quinolones from(Z)-β-chlorovinyl aromatic ketones.(Z)-β-Chloro-α,β-unsaturated ketones,simply derived from the regio-and stereoselective addition of acid chlorides to alkynes in the presence of low-cost iron catalyst,are valuable synthetic intermediates for the synthesis of various heterocyclic compounds.Herein,β-chloroalkenyl aryl ketones,derived from 2-chlorobenzoyl chlorides and terminal alkynes,can react with amines or NaSH to give quinolones or 4H-thiochromen-4-ones in the presence of base.The reaction conditions were as follows: Cs2CO3(2.0 equiv.)as the base,DMF(2 mL)as the solvent,at 140 ℃ for 20 h,the corresponding product can be obtained in 97% isolated yield.Under the standard reaction conditions,a variety of simple primary amines were applicable as starting materials,affording the corresponding products in good yields.The mild reaction conditions were compatible with various functionalities on the benzene ring of aromatic amines,thus,14 4H-thiochromen-4-ones and 22 4-quinolone derivatives were synthesized with good to excellent yields in tandem reaction manner.Finally,the possible reaction mechanism was proposed.This thesis has developed a practical,inexpensive,available and efficient method to synthesize 4H-thiochromen-4-ones and quinolin-4-ones.This protocol is not only a valuable addition to the tool box of the synthesis of heterocycles,but also enriches the contents of tandem organic synthesis.