Organocatalytic synthesis of multiple substituted bicyclo[4.4.0]decalin system

An efficient and unprecedented organocatalytic reaction of γ-nitroketones with α,β-unsaturated aldehydes to give polyfunctionalized [4.4.0] bicyclic skeletons was developed. The diphenylprolinol silyl ether mediated nitro-Michael/Aldol reaction afforded the hexa-substituted decalin carboaldehydes with excellent diastereo- and enantioselectivity (up to >99:1 dr and >99% ee) via a formal [4 + 2] carbocyclization process.     

Facile one-pot,three-component synthesis of novel bis(heterocycles) incorporating thieno[2,3-b]thiophenes via Michael addition reaction

A synthesis of novel series of bis(2-amino-3-cyano-4H-chromene), bis(2-amino-3-cyanopyrano[3,2-c]chromene), bis(6-amino-5-cyano-1,4-dihydropyrano[2,3-c]pyrazole), and bis(2,7-diamino-3,4,6-tricyanopyrazolo[1,5-a]pyridine) derivatives linked to thieno[2,3-b]thiophene core via ether or ester linkages was reported. The formation of the target compounds presumably proceeds through a three component reaction of the appropriate bis(aldehyde) with 2 M of each of malononitrile and the corresponding active methylene compounds namely; dimedone, 4-hydroxycoumarine, 5-methyl-2,4-dihydro-3H-pyrazol-3-one, or cyanomethylpyrazole in dioxane at reflux in the presence of piperdine as a basic catalyst. The chemical structures of the new compounds were elucidated by several spectral tools.     

A three-component, one-pot synthesis of indolizidines and related heterocycles via the [3+2] cycloaddition of nonstabilized azomethine ylides

Nonstabilized azomethine ylides (i.e. those bearing only hydrogens or alkyl groups) can be generated from (2-azaallyl)stannanes and (2-azaallyl)silanes through an intramolecular N-alkylation/demetalation cascade. The resulting ylides undergo [3+2] cycloaddition with electron-poor or electron-rich dipolarophiles yielding indolizidines and related 1-aza[m.3.0]bicycloalkane systems in good yield. An in situ protocol allows for a one-pot, three-component synthesis of indolizidines. The (2-azaallyl)stannanes tolerate enolizable hydrogens in these cycloadditions, while (2-azaallyl)silanes do not. The mechanism of the cycloaddition cascade is clarified by a series of control experiments. The same (2-azaallyl)stannanes may be transmetalated by n-butyllithium to generate 2-azaallyllithiums, which also may undergo a [3+2] cycloaddition/N-alkylation cascade to form indolizidines.     

Microwave-assisted,mild, facile,and rapid one-pot three-component synthesis of some novel pyrano[2,3-d]pyrimidine-2,4,7-triones

Novel pyrano[2,3-d]pyrimidine-2,4,7-triones were synthesized in 90–97% yield via a three-component reaction of an aromatic aldehyde, Meldrums acid, and barbituric acid in the presence of 10 mol % K₂CO₃ under microwave irradiation. This is the first protocol to be reported for the synthesis of title compounds and the significant features of the present protocol are simplicity, high yields, short reaction time, involvement of aqueous work-up procedure, environmentally benign nature, and no chromatographic purification.     

An efficient synthesis of imidazo[2,1-b][1,3]thiazins via a one-pot,three-component and solvent-free reaction

A simple and eco-friendly method for the synthesis of novel imidazo[2,1-b][1,3]thiazin derivatives has been developed via the one-pot, three-component and solvent-free reaction of thiohydantoins, aromatic aldehyde and 5,5-dimethylcyclohexane-1,3-dione in the presence of catalytic amount of p-toluene sulfonic acid, in good and excellent yields.     

An efficient synthesis of thiazol-2-imine derivatives via a one-pot,three-component reaction

A simple and highly efficient one-pot, three-component procedure for the synthesis of thiazol-2-imines, via the reaction of aromatic α-bromoketones, primary amines, and phenyl isothiocyanate in the presence of a catalytic amount of triethylamine, is described.     

A three-component domino reaction of 2-tetralone, hydroxylamine and acetylene: a one-pot, highly regioselective synthesis of 4,5-dihydrobenz[e]indoles

2-Tetralone, hydroxylamine and acetylene react in the system MOH/DMSO to give 4,5-dihydrobenz[e]indole and its N-vinyl derivatives in up to 41% and 75% (in the case of excess acetylene) yields, respectively. The amount of the alternative regioisomer, N-vinyl-4,9-dihydrobenz[f]indole, does not exceed 2% (GLC-MS), while the corresponding regioisomer of 4,5-dihydrobenz[e]indole is not detectable.     

Combining multi-catalysis and multi-component systems for the development of one-pot asymmetric reactions: stereoselective synthesis of highly functionalized bicyclo[4.4.0]decane-1,6-diones

We have developed a direct amine/acid-catalyzed stereoselective hydrogenation of a variety of Wieland-Miescher (W-M) ketones, Hajos-Parrish (H-P) ketones and their analogs with organic hydrides (Hantzsch esters) as the hydrogen source. This astonishingly simple and biomimetic approach was used to construct highly functionalized chiral bicyclo[4.4.0]decane-1,6-diones in a diastereoselective fashion. This is an example of the development of a new technology by the combination of multiple catalysts and components in one pot to deliver highly functionalized chiral molecules.     

Microwave-assisted intramolecular [2 + 2] Allenic cycloaddition reaction for the rapid assembly of bicyclo[4.2.0]octa-1,6-dienes and bicyclo[5.2.0]nona-1,7-dienes

Microwave irradiation of alkynyl allenes affords an intramolecular [2 + 2] cycloaddition reaction. This cycloaddition provides an efficient route to bicyclomethylenecyclobutenes. The reaction occurs with complete regioselectivity for the distal double bond of the allene for the selective formation of a variety of hetero- and carbocyclic substrates. Bicyclo[4.2.0]octadienes and bicyclo[5.2.0]nonadienes have been prepared in high yield. [reaction: see text]     

A one-pot,three-component synthesis of new pyrano[2,3-h]coumarin derivatives

The reaction between 5,7-dihydroxy-4-substituted coumarin, malononitrile, and aromatic aldehydes in the presence of a catalytic amount of K₂CO₃ as a basic catalyst leads to new pyrano[2,3-h]coumarin derivatives in good to excellent yields.     

Ultrasound-promoted one-pot, three-component synthesis of spiro[indoline-3,1'-pyrazolo[1,2-b]phthalazine] derivatives

A series of 3'-aminospiro[indoline-3,1'-pyrazolo[1,2-b]phthalazine]-2,5',10'-trione derivatives have been synthesized by a one-pot three-component reaction of isatin, malononitrile or ethyl cyanoacetate and phthalhydrazide catalyzed by piperidine under ultrasound irradiation. For comparison the reactions were carried out under both conventional and ultrasonic conditions. In general, improvement in rates and yields were observed when the reactions were carried out under sonication compared with classical conditions.     

Enantioselective synthesis of bridgehead hydroxyl bicyclo[2.2.2]octane derivatives via asymmetric allylindation

A recent new strategy for the transformation of mono-dioxolane protected 1,3-cyclohexadione into bridgehead hydroxyl bicyclo[2.2.2]octane derivatives, based on allylindation followed by ozonolysis and intramolecular aldol addition, was modified to include asymmetric allylindation. This enabled the first enantioselective synthesis of (1R,4R,6S)-endo-4-(tert-butyl-dimethyl-silyloxy)-6-hydroxy-bicyclo[2.2.2]octan-2-one and (1S,4S,6R)-endo-4-(tert-butyl-dimethyl-silyloxy)-6-hydroxy-bicyclo[2.2.2]octan-2-one in high enantiomeric excess. Issues concerning the non-reproducibility of the asymmetric allylindation were also addressed.     

Regio and diastereoselective synthesis of functionalized 2,3-dihydrofuro[3,2-c]coumarins via a one-pot three-component reaction

An efficient and straightforward synthesis of furo[3,2-c]coumarins via the one-pot three-component condensation of aromatic aldehydes, 4-hydroxycoumarin and α-chloroketones in refluxing n-propanol is described. Pyridine or a mixture of AcOH and AcONH₄ was used as a basic catalyst.     

An efficient and novel protocol for the synthesis of spiro[1,3]oxazino[5,6-c]quinoline derivatives by one-pot,three-component reaction

Research on Chemical Intermediates - One-pot, three-component reaction of various aryl glyoxal monohydrates, 5-methylisoxazol-3-amine and 4-hydroxyquinolin-2(1H)-one in the presence of a catalytic...     

Synthesis of pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolines via a one-pot,three-component reaction

A one-pot, three-component reaction for the synthesis of pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolines starting from 2-aminopyridines, phthalaldehyde, and trimethylsilyl cyanide in good to high yields is described.     

Novel stereoselective synthesis of 2,3-dihydro-1H-benzo[f]chromen-3-amine derivatives through a one-pot three-component reaction

A short and stereoselective novel synthesis of benzo[f]chromen-3-amine derivatives in good yields, through a three-component aromatic Betti type reaction under solvent free conditions is reported. The spontaneous reaction occurs in the absence of acid catalysts. The use of chiral 1-phenylethylamine or α,β-unsaturated aldehydes allowed us to prepare enantiopure benzo[f]chromen-3-amine derivatives with good stereoselectivity. Conformational analysis compared with the ¹H NMR data of the products obtained, allowed us to the determine the absolute configuration, which was also confirmed by X-ray analysis.     

Microwave-assisted efficient, one-pot, three-component synthesis of 3,5-disubstituted 1,2,4-oxadiazoles under solvent-free conditions

A novel synthesis of 1,2,4-oxadiazoles is described from a one-pot, three-component reaction between nitriles, hydroxylamine, and aldehydes under microwave irradiation and solvent-free conditions in excellent yields.     

Eco-friendly synthesis of 3-aminoimidazo [1, 2-a] pyridines via a one-pot three-component reaction in PEG catalyzed by peptide nanofibers: as hydrogen-bonding organocatalyst

Journal of the Iranian Chemical Society - Self-assembled peptide nanofibers have attracted extensive attention; they offer unique templating possibilities, which allow the synthesis of...