Preparation and characterization of MNPs–PhSO3H as a heterogeneous catalyst for the synthesis of benzo[b]pyran and pyrano[3,2-c]chromenes

Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using...     

N-acetylchloroacetamide in the synthesis of functionally-substituted pyrido[3′,2′∶4,5]-thieno[3,2-d]pyrimidin-4(3H)-ones

3-Cyano-2(1H)-pyridinethiones react with N-acetylchloroacetamide in ethanol in the presence of KOH to give pyrido[3,24,5]thieno[3,2-d]pyrimidin-4(3H)-ones.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 837–840, June, 1997.     

Cu-catalyzed dehydrogenative C?O arylation for the synthesis of 6-methyl benzofuro[3,2-c] quinoline derivatives

A novel strategy for the synthesis of 6-methyl benzofuro[3,2-c] quinoline derivatives via copper-catalyzed dehydrogenative C O arylation has been presented. Optimization studies have been carried out by varying various catalysts, bases, solvents, and other physical parameters. Keeping use of this dehydrogenative cross-coupling C O arylation reaction, a variety of bioactive building blocks like fused benzofuro quinoline heterocycles were smoothly assembled in moderate to higher yields.     

Synthesis of substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-ones and their sulfinyl and sulfonyl derivatives

A method for the synthesis of previously unknown pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-ones was suggested, which includes a condensation reaction of substituted 3-cyanopyridine-2(1H)-thiones with methyl 2-(chloromethyl)benzoate and subsequent treatment of the condensation products with potassium tert-butoxide. The oxidation of the condensation products to sulfoxides or sulfones and subsequent treatment of these compounds with potassium tert-butoxide led to substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-one 11-oxides or substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-one 11,11-dioxides.

     

Synthesis of 6H-isoindolo[2,1-a]indol-6-ones through a sequential copper-catalyzed C-N coupling and palladium-catalyzed C–H activation reaction

A series of 6H-isoindolo[2,1-a]indol-6-ones were synthesized through one-pot sequential coupling reactions, which were comprised of a copper-catalyzed C–N coupling cyclization and a palladium-catalyzed C–H activation course. General chemicals benzoyl chlorides and o-gem-dibromovinyl anilines were employed as the starting substrates.     

A metal-free C–C/C–O bond formation for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide catalyzed by polystyrene-supported p-toluenesulfonic acid (PS-PTSA)

An efficient and eco-friendly procedure for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide has been developed through a one-pot three-component condensation of 4-hydroxycoumarin with aldehydes and cyanoacetamide, in the presence of catalytic amount of polystyrene-supported p-toluenesulfonic acid (PS-PTSA) as a highly active and reusable heterogeneous acid catalyst in EtOH at 80?°C conditions. This new procedure offers several advantages such as shorter reaction times, excellent yields, a wide range of functional group tolerance, easy experimental work-up procedure, operationally simple under metal-free reaction conditions and C-C/C-O bond formation. The catalyst can be recovered and reused for at least four runs without any significant impact on the product 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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Potassium Carbonate–Mediated Efficient and Convenient Synthesis of 3-Methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones

Unprecedented cyclization was observed during N-sulfonylation of 3-[1-(phenylhydrazono)-ethyl]-chromen-2-one in pyridine, affording 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones. To avoid use of noxious pyridine, reaction was tried in different basic conditions and the best results were obtained with potassium carbonate in acetone. A wide range of substrates bearing either electron-donating or electron-withdrawing substituents on phenylhydrazine ring were compatible with the developed methodology. Rapid access of starting material, 3-acetylcoumarin, excellent yields of products, and use of environmentally benign base and solvent for the cyclization make this strategy an efficient and convenient method for synthesis of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones.     

Recent strategic advances for the activation of benzylic C–H bonds for the formation of C–C bonds

Alkylarenes, obtained from abundant hydrocarbon feedstock sources, are an attractive starting material for the formation of complex molecular architectures. Conventional activation strategies of the relatively inert sp³-hybridized benzylic C–H bonds usually require relatively harsh conditions and are difficult to apply to the synthesis of fine chemicals. The present review describes recent strategic advances for the activation of benzylic C–H bonds for the catalytic formation of C–C bonds. In particular, two activation methods, i.e., strategies that generate benzylic radicals or benzyl anions, are discussed.     

Intramolecular Ullmann-type C−N coupling for the synthesis of substituted benzo[4,5]imidazo[1,2-a]pyrrolo[3,4-c]pyridines

An efficient CuI catalyzed intramolecular Ullmann-type C−N coupling reaction is described here. Newly substituted 1H-benzo[4,5]imidazo[1,2-a]pyrrolo[3,4-c]pyridine-1,3,5(2H, 11H)-trione has been easily synthesized from ortho halogenated N-substituted pyrrolo[3,4-c]pyridine-1,3,6(5H)-triones in presence of CuI catalyst and K₂CO₃ base without any ligand. This procedure is based on intramolecular Ullmann-type reaction and provides a proficient method of making fused tetracyclic heterocycles.     

Solvent-free and three-component synthesis of 1H,6H-6λ5-[1,2]benzoxaphospholo[2,3-b][1,2]benzoxaphosphol-1-ones

A concise and facile synthesis of a new class of P,O-heterocycles is described. Knoevenagel condensation reaction of a salicylaldehyde and a cyclohexane-1,3-dione forms an α,β-unsaturated intermediate, which undergoes nucleophilic addition of a trialkyl phosphite under solvent-free conditions to afford the title compounds in good to excellent yields.     

Rhodium-catalyzed oxidative homologation of N-pyrimidyl indolines with alkynes via dual C—H activation: Facile synthesis of benzo[g] indolines

An efficient route to benzo[g]indolines by a rhodium-catalyzed C6- and C7 H functionalization of indolines with alkynes was achieved, which is potentially applicable to the synthesis of benzo[g] indoles through oxidation/removal of the directing group.     

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.     

Mild and efficient Winterfeldt oxidation of 1,2,3,4-tetrahydro-γ-carbolines for the synthesis of dihydropyrrolo[3,2-b]-quinolones and pyrrolo[3,2-b]quinolones

The Winterfeldt oxidation (NaOH, DMF, air, rt) of substituted 1,2,3,4-tetrahydro-γ-carbolines has been developed, which provides a convenient and efficient method for the synthesis of the corresponding dihydropyrrolo[3,2-b]quinolones in moderate to excellent yields (38-94%). The generality and substrate scope of this reaction are explored and a possible mechanism is proposed. The results imply that electron-withdrawing groups on N2 of tetrahydro-γ-carbolines and N5-H are necessary. The synthesis of 5 or 7-substituted pyrrolo[3,2-b]quinolones in near quantitative yields was also achieved through deprotection and aromatization of N1-Boc-dihydropyrrolo[3,2-b]quinolones.     

Domino reactions in the synthesis of benzothieno[2,3-c]pyridines. New one-pot method of preparing 2-([1]benzothieno-[2,3-c]pyridin-1-yl)benzoic acids and 8,13b-dihydro[1]benzothieno[2',3':3,4]pyrido-[2,1-a]isoindol-5(7?H)-ones

A series of previously unknown 2-([1]benzothieno[2,3-c]pyridin-1-yl)benzoic acids and 8,13b-dihydro-[1]benzothieno[2',3':3,4]pyrido[2,1-a]isoindol-5(7 H)-ones has been synthesized using domino reactions, taking place at the cyclization of 2-[3-oxo-4-(phenylsulfanyl)butyl]-1,3-isoindolinediones in polyphosphoric acid.     

Copper and zinc co-catalyzed synthesis of imidazoles via the activation of sp C–H and N–H bonds

An efficient and facile approach to synthesize imidazoles from amidines and arylketone via oxidative coupling of sp³ C–H bond and N–H bond is reported. This strategy exhibits high performance in terms of regioselectivity with moderate to high yields by using easily available materials, and provides an alternative method to synthesize multi-substituted imidazole skeletons.     

Cu(II)-β-cyclodextrin-catalyzed synthesis of spiro[indoline-3,4′-pyrano[3,2-c]chromene]-3′-carbonitrile derivatives

Cu(II)-β-cyclodextrin-catalyzed synthesis of spiro[indoline-3,4′-pyrano[3,2-c]chromene]-3′-carbonitriles through the reaction of isatin derivatives, 4-hydroxycoumarin, and malononitrile in ethanol at room temperature.     

I2–DMSO catalyzed synthesis of 1,2,2-triarylethanones via dual C–H activation of aryl methyl ketones

An I₂–DMSO promoted domino protocol was developed for the synthesis of 1,2,2-triarylethanones from readily available aromatic methyl ketones and methoxybenzenes. The 1,2,2-triarylethanones are important precursors for the synthesis of Tamoxifen and Droloxifene. The use of mild reaction conditions, high yield, and single step synthesis are the advantages of the present protocol.