Chitosan-silica Sulfate Nano Hybrid: An Efficient Biopolymer Based-heterogeneous Nano Catalyst for Solvent-free Synthesis of 3,4-Dihydropyrimidine-2(1H)-one/thiones

Abstract

A green and highly efficient approach for the synthesis of 3,4-dihydropyrimidine-2(1H)-one/thione derivatives is described. In this approach, the three-component Biginelli reaction between (thio)urea, methyl acetoacetate and aldehydes under solvent-free condition in the presence of chitosan-silica sulfate nano hybrid (CSSNH) as a green and heterogeneous nano catalyst affords the corresponding products in good to excellent yields and in short reaction times. CSSNH is a cheap, eco-friendly, and non-toxic nano catalyst that could be easily prepared, handled, and reused for many reaction runs without significant loss of its activity.

Recent advances in the application of magnetic bio-polymers as catalysts in multicomponent reactions

“…Chitosan-silica sulfate nanohybrid (CSSNH@Arg) 178 was synthesized via the reaction of chitosan 176 and silica sulfuric acid (SSA) 177 under ultrasonic irradiation ( Scheme 55 ). 76 …”

“…The various functional groups including hydroxyl and amine on the CSSNH@Arg can activate the carbonyl groups via hydrogen bonding. 76 …”

“…Chitosansilica sulfate nanohybrid (CSSNH@Arg) 178 was synthesized via the reaction of chitosan 176 and silica sulfuric acid (SSA) 177 under ultrasonic irradiation (Scheme 55). 76 A green method for the synthesis of 3,4-dihydropyrimidine-2(1H)-one/thione derivatives 179 was described by Behrouz and co-workers via the Biginelli reaction of (thio)urea 23 or urea 6, methyl acetoacetate 21, and aldehydes 19 using CSSNH@Arg 178 under solvent-free conditions (Scheme 56). According to the reusability test, this catalyst was used ve times without a decrease in any of its activities.…”

“…The various functional groups including hydroxyl and amine on the CSSNH@Arg can activate the carbonyl groups via hydrogen bonding. 76 2.6.2. Synthesis and application of Fe 3 O 4 @C-SO 3 H. Initially, starch was mixed with sulfuric acid, and then the reaction mixture was transferred to an autoclave for 24 h at 180 C, resulting in the formation of a solid black product (C-SO 3 H).…”

Efficient One-Pot Synthesis of 1,4-Dihydropyridines Catalyzed by Magnetic MnFe2O4 Nanoparticles

“…. 7H 2 O, 20 ionic liquids, 21,22 TBAB, 23 visible light, 24,25 chitosan silica sulfate, 26 molybdic acid-functionalized nano-Fe 3 O 4 @TiO 2 , 27 HClO 4 -SiO 2 , 28 microwave-assisted, 29 PW/SiO 2 , 30 solar thermal, 31 I2, 32 sulfonic acid, 33 Fe 3 O 4 @SiO 2 @OSO 3 H, 34 heteropolyacids, 35 silica gel/NaHSO 4 , 36 organocatalysis, 37 AlCl 3…”