Green Synthesis of Poly‐Substituted Pyrano[4,3‐b]quinoline‐1,9‐(5H)‐dione Derivatives Using Solid Acid as Catalyst in Water

Abstract

A series of new pyrano[4,3‐b]quinoline‐1,9(5H)‐dione derivatives were synthesized via one‐pot three‐component reaction using 6‐methyl‐4‐(arylamino)‐2H‐pyran‐2‐ones, aldehydes, and 1,3‐cyclohexanediones as substrates. The application of 4‐methylbenzenesulfonyl chloride activated the hydroxyl group of pyranone and avoided the forming of ring opening product. The reaction proceeds smoothly and gives biological and pharmacological active substituted pyrano[4,3‐b]quinoline‐1,9(5H)‐dione derivatives with good to excellent yields under green conditions. A plausible mechanism for the domino process is proposed.

Decade Advance of Isatin in Three‐component Reactions

“…Then, reactions proceeded via a sequence of Knoevenagel condensation 29.2 , Michael addition 29.3 , intramolecular cyclization 29.4 and elimination of H 2 O. As enamines surrogates, 4‐aminopyridinones, [30a] 2,6‐diaminopyrimidin‐4(3H)‐ones, [30b] 3‐amino‐cyclohex‐2‐enones, [30c,d] soxazol‐5(4H)‐ones, [30e,f] 6‐aminopyrimidine‐2,4(1H,3H)‐diones, [30e] 5‐amino‐3‐methylisoxazole, [30g] 4‐(arylamino)‐2H‐pyran‐2‐ones, [30h] hetero‐cyclic ketene aminals, [30i,k] enamino imides [30j] have all been successfully applied. Mild and green conditions are always hot topics in synthetic chemistry.…”

“…Mild and green conditions are always hot topics in synthetic chemistry. Ultrasonic irradiation, [30a] microwave irradiation , [30g] water solution, [30a–c,h] and recycling catalyst (heterogeneous solid acid C‐SO 3 H, [30a,h] silver nanoparticles, [30b] Magnetically separable Fe 3 O 4 −SO3H nanoparticles, [30d] Amberlyst‐15, [30e] aluminosilicate nanoparticles [30f] ) were developed in the past years. The development of recycling catalysts, which minimizes the consumption of auxiliary substances, energy and time required in achieving separations, can result in significant economic and environmental benefits [30f] (Scheme 29).…”