Reaction Of Active Methylene Compounds Research Articles

Mg(SPh)2 as a Catalyst for Efficient Photocatalytic Alkylation Reactions of Active Methylene Compounds with Nonactivated Alkenes

Mg(SPh)2 has been found to be a highly active catalyst in photocatalytic alkylation reactions of active methylene compounds with nonactivated alkenes. The desired reactions proceeded smoothly to afford the corresponding alkylated products in high yields with low catalyst loadings (0.2‐0.3 mol%). This protocol is applicable to a continuous‐flow system. Notably, magnesium is an earth‐abundant metal, and Mg(SPh)2 exhibits higher catalytic activity than the previously reported LiSPh.

Silica-zinc chloride (SiO2-ZnCl2) catalyzed Michael addition reaction of active methylene compounds to β-nitrostyrenes: Synthesis of functionalized pyrazole derivatives

Under solvent-free conditions, a simple and efficient procedure has been developed for the Michael addition reaction of active methylene compounds to β-nitrostyrenes. The resulting Michael adducts are efficiently converted into functionalized pyrazole derivatives with hydrazine hydrate in excellent yields. All the compounds were well characterized by spectroscopic techniques.

Immobilized sulfonic acid functionalized ionic liquid on magnetic cellulose as a novel catalyst for the synthesis of triazolo[4,3-a]pyrimidines

The Brønsted acidic ionic liquid 1-(propyl-3-sulfonate) vinyl imidazolium hydrogen sulfate [IL] was supported on modified magnetic cellulose. The physical structure, composition, and functional groups of the novel supported ionic liquid catalyst were characterized via XRD, FT-IR, EDS, SEM, VSM, TGA, TEM, and BET techniques. Owing to the combination of nano-support features and flexible imidazolium linkers, it acted as a “quasi-homogeneous” catalyst to catalyze the preparation of triazolo[4,3-a]pyrimidine derivatives by a one-pot three-component reaction of active methylene compounds (ethyl cyanoacetate or malononitrile), aminotriazole and aryl aldehydes. The catalyst shows good catalytic activity for the synthesis of triazolo pyrimidines after six times of recycling.

An efficient one-pot, three-component route to novel push–pull 1,3-benzodithiol-2-ylidenes via copper-catalyzed bis-C[sbnd]S bond formation

An efficient one-pot, three-component synthesis of novel push–pull 1,3-benzodithiol-2-ylidenes, involving reaction of active methylene compounds with CS2 in the presence of NaH as the base, followed by in situ Cu-catalyzed bis-CS coupling of the resulting dithioate salts with 1-bromo-2-iodobenzenes has been reported. The methodology involves readily available starting materials and tolerates a broad range of functional groups.

Ag2Cr2O7 nanoparticles: An eco‐friendly and reusable catalyst for synthesis of pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones in aqueous media at ambient temperature

AbstractAn efficient and green protocol for the synthesis of 4‐aryl‐3,4‐dihydro‐2H,5H‐pyrano[3,2‐c]chromene‐2,5‐diones and 8‐aryl‐7,8‐dihydro‐6H‐[1,3]dioxolo[4,5‐g]chromene‐6‐ones through the Ag2Cr2O7 nanoparticles catalyzed cyclocondensation reaction of active methylene compounds including 4‐hydroxycoumarin or 3,4‐methylenedioxyphenol, aromatic aldehydes, and meldrum's acid in water at ambient temperature was described. This method demonstrates several advantages compared with methods that are currently employed such as a mild reaction conditions, simple work‐up, good to excellent yields, avoiding toxic catalyst and hazardous solvent, and recovery and reuse of the catalyst.

Synthesis, Characterization and Antimicrobial Evaluation of Novel 6’-Amino-spiro[indeno[1,2-b] quinoxaline[1,3]dithiine]-5’-carbonitrile Derivatives

l,3-Dithiin with two sulfurs in its structure is a six-membered, sulfur-containing heterocyclic compound. New derivatives of 6'-amino-2'-(arylidene)spiro[indeno[1,2-b]quinoxaline[1,3]dithiine]-5'-carbonitrile were prepared by the multi-component reaction of active methylene compounds, carbon disulfide, malononitrile and multi-ring compounds containing a carbonyl group in the presence of piperidine as a catalyst at room temperature with high efficiency. The antimicrobial effects including antibacterial and antifungal effects based on inhibition zone diameter (IZD), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were studied.

The reaction of active methylene compounds with carbon disulfide in the presence of arylidenemalononitriles: synthesis of 6-amino-2-(4,4-dimethyl/dihydro-2,6-dioxocyclohexylidene)-4-aryl-4H-1,3-dithiine-5-carbonitrile derivatives

ABSTRACTAn efficient and simple method for the synthesis of novel ketene dithioacetals via a one-pot three-component reaction of 5,5-dimethylcyclohexan-1,3-dion or 1,3-cyclohexandion with carbon disulfide in the presence of arylidenemalononitriles is reported. The effects of different bases have been investigated and triethylamine can provide products in good to excellent yields at room temperature. The structures of all the synthesized compounds were established from advanced spectroscopic data.

Facile synthesis of heteroaryl substituted $\gamma$-lactams from nitrovinyl arenes

Aliphatic nitroalkanes with different functional groups were synthesized from the Michael addition reactions of active methylene compounds 2 and nitrovinyl arenes 1 in high yields. The synthesized Michael adducts were subjected to intramolecular cyclization to give heteroaryl substituted γ-lactams in good to high yields under mild reaction conditions.

Ambient-Light-Promoted Three-Component Annulation: Synthesis of Perfluoroalkylated Pyrimidines.

An ambient-light-promoted and metal-free three-component reaction of active methylene compounds, perfluoroalkyl iodides, and guanidines/amidines is reported. This constitutes a powerful method to prepare perfluoroalkylated pyrimidines with mild reaction conditions, broad substrate scope, excellent functional group tolerance, and simple operation. A radical/polar mechanism involving the formation of a halogen-bond adduct and radical cross-coupling is proposed.

Synthesis and antioxidant properties of novel 2H-chromene-3-carboxylate and 3-acetyl-2H-chromene derivatives

In this communication, for the first time we have constructed a series of novel azo group fused 2H-chromene-3-carboxylate and 3-acetyl-2H-chromene derivatives via the Knoevenagel condensation reaction of active methylene compounds with aromatic 5-arylazosalicylaldehydes followed by a nucleophilic addition of the phenolic hydroxyl group to the carbonyl group of one of the ester groups. Shorter reaction times, high yields, simple work-up procedure and mild reaction conditions are the advantages of the present method. In addition, we have also studied the antioxidant activities using DPPH, hydroxyl, and ABTS radical scavenging methods.

Activation of α-diazocarbonyls by organic catalysts: diazo group acting as a strong N-terminal electrophile.

For the first time α-diazocarbonyls have been used as highly active N-terminal electrophiles in the presence of bicyclic amidine catalysts. The CN bond-forming reactions of active methylene compounds as C nucleophiles with α-diazocarbonyls as N-terminal electrophiles proceed quickly under ambient conditions, in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), because of the formation of the reactive N-terminal electrophilic intermediates. DBU activates both the active methylene and α-diazocarbonyl. Importantly, this reaction is general for both active methylenes and α-diazocarbonyls, and the activation mode will lead to new synthetic applications of α-diazocarbonyls.

Activation of α‐Diazocarbonyls by Organic Catalysts: Diazo Group Acting as a Strong N‐Terminal Electrophile

AbstractFor the first time α‐diazocarbonyls have been used as highly active N‐terminal electrophiles in the presence of bicyclic amidine catalysts. The CN bond‐forming reactions of active methylene compounds as C nucleophiles with α‐diazocarbonyls as N‐terminal electrophiles proceed quickly under ambient conditions, in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), because of the formation of the reactive N‐terminal electrophilic intermediates. DBU activates both the active methylene and α‐diazocarbonyl. Importantly, this reaction is general for both active methylenes and α‐diazocarbonyls, and the activation mode will lead to new synthetic applications of α‐diazocarbonyls.

Allylation of active methylene compounds with cyclic Baylis–Hillman alcohols: a DFT study

Allylation reaction of active methylene compounds with cyclic Baylis–Hillman (BH) alcohol catalyzed by 4-dimethyamino-pyridine (DMAP) has been investigated by means of density functional theory with B3LYP/6-311++G(d,p). The first step on the chemical path is considered as an acid–base reaction. It is then followed by allylation of active methylene compound with cyclic BH alcohol. Calculated gas-phase pKa values illustrate that active methylene compounds have higher acidity than the considered cyclic BH alcohol. The DMAP catalytic activity may be interpreted as a proton transfer bridge between the active methylene compounds and the cyclic BH alcohol. Two alternative competing reactivity sites are present. Regioselectivity has been carried out on the base of natural atomic charge, Fukui index. The computations help rationalizing the fact that the direct allylation is the favored reaction and leads to the end-product.

Deep eutectic solvent-assisted one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives

Choline chloride–urea-based deep eutectic solvent (DES) has been found to be a highly effective catalyst and reaction medium for the one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives. Three-component reactions of active methylene compounds, urea or thiourea and N-bromosuccinimide NBS in deep eutectic solvent furnished structurally diverse 2-aminoxazoles and 2-aminothiazoles in good to excellent yields under mild reaction conditions and short reaction times. DES is inexpensive, biodegradable and more accessible in any laboratory and industry.

New Route for the Synthesis of Four‐Membered Cyclic Ketene Dithioacetals

AbstractNovel ketene dithioacetals have been synthesized by a one‐pot condensation reaction of active methylene compounds with CS2 in the presence of alkyl acetylenecarboxylates. This reaction proceeds in a regioselective manner and provides products in good yields. The structures of the ketene dithioacetals were characterized by IR, 1H‐ and 13C‐NMR, and MS data, and elemental analyses.

ChemInform Abstract: A Convenient Synthesis of Pyrimidinone and Pyrimidine Containing Bisheteroarenes and Analogues

Abstract[via reaction of active methylene compounds or acrylates with N‐containing precursors, viz.

Chiral Phase Transfer Catalysts for the Synthesis of Chiral N‐Heterocycles viaAsymmetric Cascade Reactions

The effectiveness of a series of chiral phase transfer catalysts in cascade reactions of active methylene compounds with 2‐cyanobenzaldehyde leading to chiral 3‐substituted isoindolinones and fused benzoindolizidinones has been investigated. High yields and moderate enantiomeric excesses (e.e.s) were achieved employing a chiral phase‐transfer catalyst derived from bifunctional urea–quinine. Moreover, an efficient process of heterochiral crystallization, performed on moderately enantioenriched compounds, led to an impressive increase of the enantiopurity up to 93% e.e.s.

Tetrabutylphosphonium amino acid ionic liquids as efficient catalysts for solvent-free Knoevenagel condensation reactions

Five tetrabutylphosphonium amino acid ionic liquids ([P4444][AA]) were prepared, characterized, and used as catalysts for solvent-free Knoevenagel condensation reactions. The tetrabutylphosphonium prolinate ([P4444][Pro]) showed excellent catalytic activity and selectivity in Knoevenagel condensation reactions of active methylene compounds with various aromatic aldehydes, and all the yields of corresponding products were more than 85% under mild conditions. Furthermore, a plausible reaction mechanism for the excellent performance of [P4444][Pro] has been proposed, and [P4444][Pro] could be used repetitively at least six times without obvious decrease in activity and quantity.

ChemInform Abstract: A Highly Negatively Charged γ‐Keggin Germanodecatungstate Efficient for Knoevenagel Condensation.

AbstractThe title compound is synthesized and applied as homogeneous catalyst for the Knoevenagel reaction of active methylene compounds (II) with carbonyl compounds, e.g. (I).

The Aldol Reactions of Active Methylene Compounds

The aldol addition of active methylene compounds has been shown to be an important challenge for current organic chemistry, even if the aldol adducts can be particularly useful in the synthesis of complex valuable molecules. Starting from the early unsuccessful attempts employing “standard” methodologies, this review describes the most recent successful one-pot multicomponent procedures and the first examples of synthesis of valuable compounds, both cyclic and acyclic. Keywords: Aldol reactions, Active methylene compounds, Multi-component reactions, Tandem reactions, Heterocyclic compounds, Organocatalysis, Metal catalysts