Regioselective palladium-catalyzed Suzuki–Miyaura coupling reaction of 2,4,6-trihalogenopyrido[2,3-d]pyrimidines

An effective, regioselective, and novel strategy to the access of 2,4,6-trisubstituted pyrido[2,3-d]pyrimidines is developed from the corresponding 2,4,6-trihalogenopyrido[2,3-d]pyrimidine through a Suzuki–Miyaura coupling reaction involving a novel regioselective halogen discrimination.     

Pd-NHC catalyzed Suzuki–Miyaura couplings on 3-bromo-9H-pyrido[2,3-b]indole-6-sulfonamide

A series of novel α-carboline derivatives such as 3-aryl-9H-pyrido[2,3-b]indole-6-sulfonamides have been synthesized from the readily available low-cost raw material, benzotriazole which is subjected to nucleophilic aromatic substitution with 5-bromo-2-chloropyridine followed by sequential steps of cyclization, sulfonation, amidation, and finally Suzuki–Miyaura coupling reactions. The C–C bond formation between 3-bromo-9H-pyrido[2.3-b]indole-6-sulfonamide and various boronic acids was achieved with more accessible palladium pre-catalyst, Pd-PEPPSI-IPr via Suzuki coupling under microwave condition in a short reaction time with excellent yields.     

Palladium-catalyzed one-pot Suzuki–Miyaura cross coupling followed by oxidative lactonization: a novel and efficient route for the one-pot synthesis of benzo[c]chromene-6-ones

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Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[α]pyrano[2,3-c]phenazine]and benzo[α]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green,convenient,high yielding and one-pot procedure for the synthesis of novel spiro[benzo[α]pyrano[2,3-c]phenazine]derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-l,4-dione,benzene-l,2-diamines,ninhydrine,and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione(theophylline) as an expedient,eco-friendly and reusable solid base catalyst under thermal,microwave irradiation and solvent-free conditions.This procedure has also been applied successfully for the synthesis of benzo[α]pyrano[2,3-c]phenazines.     

Expeditious one-pot multicomponent microwave-assisted green synthesis of substituted 2-phenyl Quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-b]pyrazine in water–PEG and water–ethanol

An eco-friendly, expeditious one-pot multicomponent synthesis of substituted 2-phenyl quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-b]pyrazine 4a–k in water–ethanol from easily available starting materials as acetophenone 1, succinamide 2, aromatic amine 3, in situ-generated α-iodo acetophenone from acetophenone, succinamide and catalyzed by silver iodide in combination with green solvent polyethylene glycol-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of products in very short time of reaction by avoiding the use of lacrimatic α-chloro and α-bromocarbonyl compounds, volatile, toxic organic hazardous solvents, and reagents is the advantage of this research work. The final products were confirmed by their characterization data such as FTIR, ¹H NMR, ¹³C NMR, Mass, HRMS and were compared with its reported method.     

l-Proline catalyzed efficient one-pot three-component aza-Diels–Alder reactions on nitrostyrylisoxazoles: a facile synthesis of new isoxazolyl tetrahydroquinolines and isoxazolo[2,3-a]pyrimidines

l-Proline acts as an efficient organocatalyst and found to promote one-pot three-component aza-Diels–Alder reaction of aryl or isoxazole imines formed in situ from aromatic or isoxazoleamines and aromatic aldehydes with nitrostyrylisoxazoles to afford the isoxazolyl tetrahydroquinolines or isoxazolo[2,3-a]pyrimidines, respectively, in excellent yields at ambient temperature under neutral conditions.     

Cyclization of alk-4-ynals with o-diaminoarenes as a selective one-pot synthesis of arylmethylidene-substituted 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazoles and 7,8-dihydro-6H-pyrrolo[1’,2’:1,2]imidazo[4,5-b]pyridines

Russian Chemical Bulletin - A one-pot synthesis of arylmethylidene-substituted 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazoles based on the reaction of alk-4-ynals with 1,2-diaminobenzenes in DMSO at...     

A new method for the formation of the imidazo[4′, 5′; 3,4] pyrido[2,3-b]indole ring: Formal synthesis of the alkaloids from marine origin grossularines-1 and 2

A new synthesis of the 2-dimethylamino-4-hydroxy-6-methoxymethyl-3H-imidazo[4′, 5′:3,4] pyrido[2,3-b]indole, used as key intermediate in the total synthesis of the alkaloids grossularines-1 and -2, based on the step-wise formation of the pyridine and imidazole rings, is described.     

A new convenient four-component synthesis of 6-amino-2H, 4H-pyrano[2,3-c]pyrazole-5-carbonitriles and one-pot synthesis of 6 ′-amino-5-cyano-1,2-dihydrospiro-[(3H)-indole-3,4 ′-(4 ′H)-pyrano[2,3-c]pyrazol]-2-ones

A new convenient method for the synthesis of 6-amino-2H,4H-pyrano[2,3-c]pyrazole-5-carbonitriles, namely, four-component condensation of carbonyl compounds (aromatic aldehydes, heterocyclic ketones), malononitrile, β-keto esters, and hydrazine hydrate in ethanol in the presence of triethylamine as a catalyst, which occurs selectively, is developed. One-pot two-step modification of this method is proposed for the synthesis of spiro[(3 H)-indole-3,4 ′-(4′H)-pyrano[2,3-c]pyrazol]-2-ones.     

Efficient and facile synthesis of 5-arylindeno[2′,1′:5,6]pyrido[2,3-d] pyrimidine-2,4(3H)-dione and 7-arylbenzo[h]pyrimido[4,5-b]quinoline-8,10(5H,9H)-dione under mild conditions

An efficient and facile method for the synthesis of 5-arylindeno[2′,1′:5,6]pyrido[2,3-d] pyrimidine-2,4(3H)-dione and 7-arylbenzo[h]pyrimido[4,5-b]quinoline-8,10(5H,9H)-dione derivatives from the reactions of 2-arylidene-2,3-dihydroinden-1-one (or 2-arylidene-3,4- dihydronaphthalen-1(2H)-one) and 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione under mild conditions was described. This is a simple, efficient, and very rapid synthetic method, which is believed to provide a useful process for the synthesis of these fused heterocyclic compounds. The products were confirmed by infrared, ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry.     

Fe3O4@SiO2–NH2 core-shell nanocomposite as an efficient and green catalyst for the multi-component synthesis of highly substituted chromeno[2,3-b]pyridines in aqueous ethanol media

ABSTRACT

An efficient and green approach for synthesizing chromeno[2,3-b]pyridine derivatives through one-pot three-component reactions of salicylaldehydes, thiols, and malononitrile has been developed by Fe₃O₄@SiO₂–NH₂ nanocatalyst in aqueous ethanol media under re?ux conditions. The present procedure provides several advantages such as environmentally benign, straightforward, excellent yields, short reaction times, cost-effective, good recyclability, little catalyst loading, and facile catalyst separation for the preparation of chromeno[2,3-b]pyridines as important privileged medicinal scaffold. In addition, aminopropyl-coated Fe₃O₄@SiO₂ nanoparticles were fully characterized by scanning electron microscopy, X-ray diffraction, energy dispersive analysis of X-ray, vibrating sample magnetometer, and FT-IR analysis.     

Synthesis and characterization of silica-coated Fe3O4 nanoparticle@silylpropyl triethylammonium polyoxometalate as an organic–inorganic hybrid heterogeneous catalyst for the one-pot synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones

In this study, silica-coated Fe₃O₄ nanoparticle@silylpropyl triethylammonium polyoxometalate catalyst was fabricated and characterized using atomic absorption, inductively coupled plasma optical emission spectrometry, elemental analysis, thermogravimetric analysis, Fourier-transform infrared, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry analyses. The activity of this catalyst was examined in the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones. The bonding of the polyoxometalate to the surface of the nanoparticles exhibited excellent catalytic activity in this synthesis. Besides, the catalyst showed good reusability and recovery from the reaction mixture. Tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones were synthesized in high yields in the presence of inexpensive supported solid acid catalysts under classical heating conditions.