Electrocatalytic multicomponent assembling of phthalhydrazide,aldehydes and malononitrile: An efficient approach to 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

Electrocatalytic multicomponent transformation of phthalhydrazide, aromatic aldehydes and malononitrile in n-propanol in an undivided cell in the presence of sodium bromide as an electrolyte leads to 1H-pyrazolo[1,2-b]phthalazine-5,10-diones in short reaction times (4–8 min) and high yields (85–98%) at room temperature. The developed efficient electrocatalytic approach to the corresponding 1H-pyrazolo[1,2-b]phthalazine-5,10-diones is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a new example of the ecologically pure synthetic concept for electrocatalytic multicomponent reactions strategy.     

Electrocatalytic multicomponent assembling of aldehydes, 4-hydroxycoumarin and malononitrile: An efficient approach to 2-amino-5-oxo-4,5-dihydropyrano(3,2-c)chromene-3-carbonitrile derivatives

2-Amino-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile derivatives are obtained in excellent yields by a simple, mild and efficient procedure by an electrocatalytic multicomponent chain transformation of aryl aldehydes, 4-hydroxycoumarin and malononitrile under neutral and mild conditions by electrolysis in an undivided cell in the presence of sodium bromide as an electrolyte.     

Solvent-free cascade reaction: direct multicomponent assembling of 2-amino-4H-chromene scaffold from salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes

The new type of solvent-free cascade reaction was found: the direct heating of the mixture of salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes at 60 °C in the presence of catalytic amounts of KF or NaOAc results in the formation of 2-amino-4-(1-nitroalkyl)-4H-chromene-3-carbonitriles or methyl 2-amino-4-(1-nitroalkyl)-4H-chromene-3-carboxylates in 80-90% yields. Thus, the new simple and efficient solvent-free ‘one-pot’ way to substituted medicinally privileged 2-amino-4H-chromene scaffold was found directly from such simple and reasonable starting compounds as salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes.     

Multicomponent assembling of salicylaldehydes,malononitrile and cyanoacetamides: A simple and efficient approach to medicinally relevant 2-amino-4H-chromene scaffold

Sodium hydroxide catalyzed a new multicomponent reaction of salicylaldehydes, malononitrile and cyanoacetamides under ‘on-water’ conditions, which results in the facile and efficient formation of the corresponding substituted 2-amino-4H-chromenes in 80–95% yields. The convenient approach to the substituted 2-amino-4H-chromenes developed here — the promising small-molecule ligands for different biomedical applications with known spasmolitic, diuretic and antianaphylactic activities — is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a fast, efficient and environmentally benign ‘on-water’ synthetic concept for multicomponent reactions strategy.     

Sodium acetate catalyzed multicomponent approach to medicinally privileged 2-amino-4H-chromene scaffold from salicylaldehydes,malononitrile and cyanoacetates

Sodium acetate-catalyzed multicomponent assembling of salicylaldehydes, malononitrile and cyanoacetates in water–alcohol mixture (1: 1) at ambient temperature affords alkyl (2-amino-3-cyano-4H-chromen-4-yl)cyanoacetates in 88–95% yields.     

Electrocatalytic cascade multicomponent assembling: stereoselective one-pot synthesis of the substituted 3-azabicyclo[3.1.0]hexane-1-carboxylate system from aldehyde, malononitrile, malonate and methanol

Electrolysis of aromatic aldehydes, malononitrile and malonate in methanol in an undivided cell in the presence of sodium bromide-sodium methoxide as double mediatory system results in the stereoselective formation of methyl (1R^∗,5R^∗,6R^∗) 6-substituted 5-cyano-4,4-dialkoxy-2-oxo-3-azabicyclo[3.1.0]hexane-1-carboxylates in 50-70% yields.     

Electrocatalytic multicomponent transformation of cyclic 1,3-diketones, isatins, and malononitrile: facile and convenient way to functionalized spirocyclic (5,6,7,8-tetrahydro-4H-chromene)-4,3′-oxindole system

An electrochemically induced catalytic multicomponent transformation of cyclic 1,3-diketones, isatins, and malononitrile in alcohols in an undivided cell in the presence of sodium bromide as an electrolyte results in the formation of spirooxindoles with fused functionalized 5,6,7,8-tetrahydro-4H-chromene system in 83-98% yields. The application of this efficient electrocatalytic method to the formation of medicinally relevant spirocyclic (4H-chromene)-4,3′-oxindoles is beneficial from the viewpoint of diversity-oriented large-scale processes and represents novel, facile, and environmentally benign synthetic concept for multicomponent reaction strategy.     

Multicomponent assembling of salicylaldehydes,malononitrile, and 4-hydroxy-6-methyl-2H-pyran-2-one: A fast and efficient approach to medicinally relevant 2-amino-4H-chromene scaffold

A new multicomponent reaction (MCR) was found: a sodium acetate-catalyzed transformation of salicylaldehydes, malononitrile and 4-hydroxy-6-methyl-2H-pyran-2-one in ethanol results in the fast (30 min) and efficient formation of new 4-pyrano-substituted 2-amino-4H-chromenes in 86–96% yields. The same transformation initiated by grinding in mortar in the presence of sodium acetate or potassium fluoride results in a faster (15 min) formation of 4-pyrano-substituted 2-amino-4H-chromenes in 80–90% yields. This novel ‘one-pot’ process opens an effective and convenient way to pyrano-functionalized 2-amino-4H-chromene systems, which are promising compounds for different biomedical applications.     

An efficient non-catalytic, regioselective approach to the synthesis of angularly fused polycyclic systems

A novel approach to the synthesis of partially reduced different ring sizes of PAH analogs with sec.amino and nitrile functionalities is delineated through base-induced ring transformation of 4-sec.amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by a carbanion, generated in situ from cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone separately in good yields. An increase in the size of cycloalkanone ring beyond cyclooctanone restricts the ring transformation under analogous reaction conditions possibly due to bulky conformation of higher homologs. The synthetic method provides an efficient general route for the construction of angularly fused partially reduced polycyclic aromatic hydrocarbons: 5-sec.amino-2,3,6,7-tetrahydro-1H-cyclopenta[c]phenanthrene-4-carbonitriles, 6-sec.amino-2,3,4,7,8-pentahydro-1H-benzo[c]phenanthrene-5-carbonitriles, 7-sec.amino-2,3,4,5,8,9-hexahydro-1H-cyclohepta[c]phenanthrene-6-carbonitriles, and 8-sec.amino-2,3,4,5,6,9,10-heptahydro-1H-cycloocta[c]phenanthrene-7-carbonitriles.     

An approach to biologically important S‐heterocycles,dithiocarbamyls, and their relevant phosphono derivatives

The feasibility of insertions of carbanions between two sulfur atoms has been reported when 5‐(4‐chlorophenyl)‐4‐cyano‐1,2‐dithiol‐3‐thione ( 1 ) and tetramethylthiuram disulfide ( 17 ) were allowed to react with unsaturated 2a,b and active phosphonium salts 11a,b . The reactions afforded, mainly, 1,3‐dithiols 4a,b and 14a,b together with substituted thiophenes 10a,b and 16a,b . Reactions of 1 and 17 with α‐alkylthiomethyl phosphonates 24a,b afforded the phosphonates 25a,b and 26a,b , respectively.     

Allenes and transition metals: a diverging approach to heterocycles

[reaction: see text] An alkynyl allene has been converted to heterocycles possessing an alpha-alkylidene cyclopentenone, a 4-alkylidene cyclopentenone, or a cross-conjugated triene. Thus, a common intermediate has been converted to three structurally unique compounds by changing only the reaction conditions and, therefore, controlling various reaction pathways.     

Electrocatalytic multicomponent cyclization of aromatic aldehydes,malononitrile, and malonates into 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates

Electrolysis of aromatic aldehydes, malononitrile and malonates in methanol in an undivided cell in the presence of double-mediator system NaBr-NaOAc afforded 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates in 40–60% yields.     

[3+3]-Cyclocondensation of aminomethylenecycloalkanones with cyclic azomethines — A new approach to condensed nitrogen heterocycles

A new method was developed for the synthesis of condensed azinium salts with a nitrogen atom in the ring fusion based on the [3+3]-cyclocondensation of aminomethylenecycloalkanones and cyclic azomethines.Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, 220141 Minsk. Institute of Pharmacology, Ministry of Health of the Russian Federation, 117607 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 972–974, July, 1997.     

Modeling and optimizing toughness and rigidity of PA6/SBR: Using compatibilizer and response surface methodology

The improvement of miscibility between toughened Polyamide-6 (PA6) and Styrene-Butadiene Rubber (SBR) was carried out using grafted Glycidyl Methacrylate (SBR-g-GMA). At first, the compatibilizers were prepared using different comonomers, Styrene, and N-vinyl pyrrolidone. Central composited design (CCD) was distinctly applied to study the influence of Glycidyl Methacrylate (GMA) content and comonomer/GMA on the process of compatibilizer preparation. Four models were developed for Gel content and Degree of grafting for both comonomers using Design-expert software. The models were used to calculate the optimum operating conditions and according to the Flory-Huggins parameter and obtained results, SBR-co-NVP-g-GMA was chosen as an effective compatibilizer. Afterward, another CCD was employed to scrutinize the effect of various amounts and grafting degree of compatibilizer on morphology and mechanical properties of PA6/SBR. The Interparticle distance and polydispersity were studied using a Scanning electron microscope (SEM) and also the Izod impact test inspected in order to evaluate the mechanical properties. Finally, modulus and impact strength were optimized to minimize the former and maximize the latter. Also, the most practical terms in the fitted model are statistically specified using F-value. The root causes for the improvement of blend properties were attributed to a chemical reaction between epoxy groups in SBR-g-GMA and both the carboxylic and amine groups in PA6. Impact strength (539.8 J/m) and modulus (2017.2 N/mm²) of the optimum blend indicate an excellent agreement with the amounts predicted by the models.     

Direct, one-step synthesis of condensed heterocycles: a palladium-catalyzed coupling approach

[reaction: see text] A palladium-catalyzed one-step synthesis of fused aromatic heterocycles from bifunctional bromoenoates or bromoalkyl indoles and iodoarenes is reported. This method provides an efficient route to a wide variety of substituted polycyclic aromatic and heteroaromatic compounds from readily accessible starting materials.