Highly efficient catalyst-free domino conjugate addition, decarboxylation and esterification/amidation of coumarin carboxylic acid/esters with pyrazolones: a green chemistry approach

Abstract

Tandem conjugate addition, decarboxylation and esterification/amidation of coumarin 3-carboxylic acid derivatives with pyrazolones have been developed.

Graphene Oxide Catalyzed Synthesis of Fused Chromeno Spiro Pyrrolidine Oxindoles via Tandem Decarboxylation and 1,3-Dipolar Cycloaddition

“…Currently, the synthesis of complex molecules having appealing stereochemistry being synthesized by relatively simple protocol and environmental conscience is of utmost importance and can be largely correlated by frequent reports occurring in literature (Sharma et al, 2021;Singh et al, 2021). As a part of our group's research interest in sustainable and operationally simple, efficient sequences, we wish to report a simple and effective method mediated by azomethine ylide for the construction of a library of complex spiro-pyrrolizineindoline and spiro-pyrroleindoline molecules via 1,3-dipolar cycloaddition reaction in a one-pot, multicomponent approach using a heterogeneous catalyst (Chowhan et al, 2019;Lakshmi et al, 2020). Our synthetic approach started with 1,3-dipolar cycloaddition of α,β-unsaturated carbonyl compounds in equimolar concentrations, i.e., coumarin 3 and non-stabilized azomethine ylide, in situ generated via the condensation of isatin 1 and L-proline 2 in protic solvents (Scheme 1; Table 1).…”

Water Extract of Lemon (WEL) as a Promoter: Green and Regioselective Synthesis of Alkyl‐4‐(1H‐indol‐3 yl)‐2‐alkyl‐4H‐chromene‐3‐carboxylates Using 4H‐chromenes and Indoles

“…However, in this protocol, we selectively identified the formation of compound (3) rather another regioisomer (4). [31] Therefore, electron-deficient benzopyrylium cation I have attacked at C-4 position carbon by incoming indole to furnish corresponding region-isomer (3) selectively. The C4 position is in conjugation with ester group of C3 which makes C4 as a good Michael acceptor.…”

Direct Michael addition/decarboxylation reaction catalyzed by a composite of copper ferrite nanoparticles immobilized on microcrystalline cellulose: an eco-friendly approach for constructing 3,4-dihydrocoumarin frameworks

“…22,23 Considering the tremendous therapeutic signicance and broad-spectrum chemical landscape of coumarins, the past decades have witnessed immense efforts not just for their synthesis but also Scheme 1 for their utilization as a testing ground in the discovery of new reactions and the synthesis of complex hybrid molecules of medicinal interest. 24 Especially, the exploitation of carboxylic acid/ester functionalized coumarins as Michael acceptors for the assembly of 3,4-dihydrocoumarin has recently gained immense importance. But, due to loosing its aromatic nature, harsh reaction conditions are desired which marks the limitations of the reaction scopes as previously reported works, Michael addition via ringopening/decarboxylation at high temperature or using organocatalyst.…”

“…22,23 Considering the tremendous therapeutic significance and broad-spectrum chemical landscape of coumarins, the past decades have witnessed immense efforts not just for their synthesis but also Scheme 1 for their utilization as a testing ground in the discovery of new reactions and the synthesis of complex hybrid molecules of medicinal interest. 24…”