Glycine Catalyzed One-Pot Three-Component Synthesis of Structurally Diverse 2-Amino Substituted Pyran Annulated Heterocycles in Aqueous Ethanol under Refluxed Conditions

Abstract

INTRODUCTION: A facile, convenient and general method has been developed for the one-pot three-component synthesis of structurally diverse 2-amino pyran annulated heterocycles from the reactions of aromatic aldehydes, malononitrile and various C-H activated acids in the presence of a catalytic amount of glycine as an efficient metal-free organocatalyst in aqueous ethanol under refluxed conditions. METHOD: Using this developed protocol, we were able to synthesize a series of structurally diverse 2-amino pyran derivatives viz., 2-amino-4,5-dihydropyrano[3,2-c]chromenes, 2-amino-4,5-dihydropyrano[4,3-b]pyrans, 2-amino-5,6,7,8-tetrahydro-4H-chromenes, 2'-amino-2,5'-dioxo-5'H-spiro[indoline-3,4'-pyrano[3,2-c]chromene]-3'-carbonitrile and 2'-amino-1,3,5'-trioxo-1,3-dihydro-5'H-spiro[indene-2,4'-pyrano[3,2-c]chromene]-3'-carbonitrile in excellent yields. RESULT: Synthesis of biologically promising pyrans and spiropyrans, high atom economy, excellent yields, use of metal-free catalyst, less toxic solvents, no chromatographic column purifications, multiple carbon-carbon and carbon-heteroatom bond formations are some of the major advantages of this newly developed protocol.

One‐Pot Three‐Component Synthesis of Biologically Promising Indenoquinoxaline Fused Spiroheterocycles Starting from 11H‐indeno[1,2‐b]quinoxalin‐11‐ones

“…Multi‐component synthesis involves combination of at least three reactants in one pot to obtain the desired product with maximum atom economy and minimum production of the waste materials [25] . Multi‐component reaction strategy is considered as economical as well as one of the greenest tool to synthesize various heterocyclic compounds for its multiple advantages such as operational simplicity, reduction of purification processes, high atom economy, energy efficiency and many more [26–30] …”

“…[25] Multi-component reaction strategy is considered as economical as well as one of the greenest tool to synthesize various heterocyclic compounds for its multiple advantages such as operational simplicity, reduction of purification processes, high atom economy, energy efficiency and many more. [26][27][28][29][30] In continuation of our strong interest about various bioactive heterocyclic or spiroheterocyclic scaffolds, [31][32][33][34][35][36][37][38][39][40] in the following sections we have discussed a series of one-pot three-component reaction protocols for the synthesis of structurally diverse spiroheterocycles involving 11H-indeno [1,2-b]quinoxalin-11-one as one of the starting reactant under various reaction conditions.…”

Fe3O4@nano-almondshell/Si(CH2)3/2-(1-piperazinyl)ethylamine as an effective magnetite almond shell-based nanocatalyst for the synthesis of dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyran derivatives

“…Dihydropyrano[3,2- c ]chromene and tetrahydrobenzo[ b ]pyran are heterocyclic organic compounds containing oxygen and are very attractive. For this reason, so far, many catalysts including ZnO NPs 30 , t-ZrO 2 NPs 31 , SB-DABCO@eosin 32 , Fe 3 O 4 @GO-NH 2 33 , [PEMIM][OH] 34 , [(EMIM)Ac] 35 , L-Proline 36 , Chitosan-ZnO 37 , CESA 38 , Glycine 39 , rGO@Fe 3 O 4 @ZrCp 2 Cl 2 40 , Fe 3 O 4 @ G.tea /Cu 41 , etc. have been used for the synthesis of this class of compounds.…”