Autotandem Catalysis: Inexpensive and Green Access to Functionalized Ketones by Intermolecular Iron-Catalyzed Amidoalkynylation/Hydration Cascade Reaction via N-Acyliminium Ion Chemistry

Iron-based catalysts were applied in cascade-type reactions for the synthesis of different carbonyl compounds. The reactions proceeded by a new iron-catalyzed cascade of alkynylation/hydration by using both the σ- and π-Lewis acid properties of iron salts. The alkynylation reactions of several endo and exocyclic acetoxylactams were achieved with three different catalysts including FeCl 3 .6H 2 O, FeCl 3 , and Fe(OTf) 3 showing the efficiency of σ-Lewis acidity of iron (III) salts in catalyzing the alkynylation reaction. We also demonstrated that the reaction sequence could be shortened by the direct use of hydroxylactams, leading to an environmentally friendly protocol, avoiding the need to perform unnecessary lengthy steps. A combination of the hard/soft iron Lewis acid properties was then used to implement an unprecedented tandem intermolecular alkynylation/intramolecular hydration sequence allowing expedient access to a new carbonyl structures from trivial materials.

Organic synthesis with the most abundant transition metal–iron: from rust to multitasking catalysts

The promising aspects of iron in synthetic chemistry are being explored for three-four decades as a green and eco-friendly alternative to late transition metals. This present review unveils these rich iron-chemistry towards different transformations.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.

Modern Catalysts in A3- Coupling Reactions

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Propargylamines are an important constituent of diverse, biologically active and industrially valuable compounds. These useful, convenient and effective compounds can be synthesized via the A3-coupling reactions between an aldehyde, amine, and alkyne in the presence of a catalyst. In the past years, most of the catalysts containing transition metals were applied in these reactions, but today, various heterogeneous catalysts, especially nanocatalysts are used. The purpose of this review was to introduce some modern catalysts for the A3-coupling reaction.

Oxidative sulfonamidomethylation of imidazopyridines utilizing methanol as the main C1 source

An efficient one pot, three component synthesis of C3 sulfonamidomethylated imidazopyridines has been disclosed under metal-free conditions, which utilized the commercially available and renewable reagent methanol as the main methylene source. A wide range of substituted imidazopyridines and sulfamides/amines were well tolerated to afford the corresponding products in up to 92% yield. In the isotopic labelling experiment, it was found that a minor part of the methylene also originated from DTBP. Moreover, the radical scavenger reactions were conducted, which suggested that a free-radical mechanism was probably not involved. The current methodology featured several advantages, including broad substrate scope, good functional group tolerance and high reaction efficiency.

FeCl3-promoted tandem 1,4-conjugate addition/6-endo-dig cyclization/oxidation of propargylamines and benzoylacetonitriles/malononitriles: direct access to functionalized 2-aryl-4H-chromenes

An efficient and concise procedure has been developed for the synthesis of functionalized 2-aryl-4H-chromenes based on a tandem reaction of propargylamines and benzoylacetonitriles/malononitriles in the presence of FeCl3 as an environmentally friendly promoter. This reaction involves a highly efficient tandem sequence consisting of 1,4-conjugate addition, 6-endo-dig cyclization, and oxidation. This protocol tolerates a variety of functional groups, thereby providing a practical and efficient method for the fabrication of 2-aryl-4H-chromene skeletons.

Recyclable Cu/C3N4 composite catalyzed AHA/A3 coupling reactions for the synthesis of propargylamines

The heterogeneous Cu/C3N4 catalyst was found to be efficient for the synthesis of propargylamines using a three-component coupling reaction of alkynes, CH2Cl2 and amines (AHA) without additional base. Moreover, the catalyst also showed highly catalytic activity in the synthesis of C1-alkynylated tetrahydroisoquinolines (THIQs) via an A3 reaction of alkynes, aldehydes and THIQ. The Cu/C3N4-catalyzed multicomponent reactions exhibited good functional group tolerance in most examples. Furthermore, the easily prepared Cu/C3N4 catalyst could be recovered and reused conveniently over 5 times without losing catalytic activities.

A concise synthesis of indene-based polycyclic compounds via FeCl3-catalyzed cascade cyclization

An efficient and straightforward protocol to complex indene-based polycyclic compounds via the cascade cyclization of propargylic alcohols and alkenes was developed. The catalyst FeCl₃, as an Earth-abundant and environment friendly transition metal salt, is attractive. This reaction proceeded through unusual C–C bond cleavage.

Synthesis and Reactivity of Propargylamines in Organic Chemistry

Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A³ couplings and C-H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses. Both racemic and enantioselective approaches have been reported. In the second part, an overview of the transformations of propargylamines into heterocyclic compounds such as pyrroles, pyridines, thiazoles, and oxazoles, as well as other relevant organic derivatives, is presented.

Zn(ii) anchored onto the magnetic natural hydroxyapatite (ZnII/HAP/Fe3O4): as a novel, green and recyclable catalyst for A3-coupling reaction towards propargylamine synthesis under solvent-free conditions

In this paper, Zn(ii) anchored onto the magnetic natural hydroxyapatite (Zn^II/HAP/Fe₃O₄), as a new and magnetically recoverable catalyst, was prepared and characterized using different techniques such as FT-IR, XRD, TGA, TEM, EDX, VSM and ICP.

Silica nanospheres supported diazafluorene iron complex: an efficient and versatile nanocatalyst for the synthesis of propargylamines from terminal alkynes, dihalomethane and amines

A novel silica nanosperes supported diazafluorene iron complex has been fabricated and found to be effective in three-component coupling reaction of terminal alkynes, dichloromethane and amines.

Efficient three-component coupling reactions catalyzed by Cu0-nanoparticles stabilized on modified montmorillonite

In situgeneration of Cu⁰-nanoparticles into the nanopores of environmentally benign modified montmorillonite clay and their catalytic performance in three component (A³) coupling reactions of aldehyde, amine and alkyne to synthesize propargylamines with excellent yields and selectivity.

Efficient one-pot synthesis of propargylamines catalysed by gold nanocrystals stabilized on montmorillonite

Size selective Au⁰-nanoparticles were generatedin situin the nanopores of montmorillonite and applied in the one-pot, three-component coupling of an aldehyde, an amine and an alkyne to synthesize propargylamines.