Efficient One‐Pot Synthesis of Novel Spirooxindole‐Fused Phosphorous Heterocycle Derivatives by a Three‐Component Domino Reaction

A highly efficient, catalyst‐free, and regioselective synthesis of structurally diverse spirooxindole‐fused phosphorous heterocycle derivatives was constructed in good yields by means of a three‐component domino reaction of isatins, dichlorophenylphosphine or phenyl phosphorodichloridite, and o‐aminophenol in tetrahydrofuran reflux. The advantages of this method include high efficiency, mild reaction conditions, and environmentally benign reagents. These spirooxindole‐fused phosphorous heterocycles are promising candidates for drug discovery.     

Task‐specific Ionic Liquid Mediated Eco‐compatible Approach for the Synthesis of Spirooxindole Derivatives and Their DNA Cleavage Activity

Guanidine‐based task‐specific ionic liquid 1,1,3,3‐tetramethylguanidine acetate [TMG][Ac]was found to be a very effective solvent for the synthesis of pharmaceutically important spirooxindole derivatives through one‐pot multicomponent reaction of substituted isatin, thiazolidine‐4‐carboxylic acid and naphthoquinone followed by the spontaneous dehydrogenation in excellent yields without using any reagent and catalyst. The TMG‐based ionic liquid could be recovered and used at least four times without considerable reduction in its activity. The advantageous features of the developed synthetic protocol are high atom economy, operational simplicity, shorter reaction time, easily handling, and environmentally benign. The structure and relative stereochemistry of final products was established by single crystal X‐ray structure and spectroscopic techniques. The synthesized compounds were subjected for DNA cleavage activity.     

Chiral Iodine‐Catalyzed Dearomatizative Spirocyclization for the Enantioselective Construction of an All‐Carbon Stereogenic Center

The first enantioselective dearomatizative spirocyclization of 1‐hydroxy‐N‐aryl‐2‐naphthamide derivatives has been accomplished by chiral organoiodine catalysis to stereoselectively create an all‐carbon stereogenic center, providing a straightforward approach to access spirooxindole derivatives in good yields and with high to excellent levels of enantioselectivity. Chiral hypervalent phenyl‐λ³‐iodanes generated in situ from the oxidation of the chiral phenyl iodine actually participate in the asymmetric oxidative dearomatizative spirocyclization reaction.     

Application of Sulfonic Acid Functionalized SBA‐15 as a New Nanoporous Acid Catalyst in the Green One‐Pot Synthesis of Spirooxindole‐4H‐pyrans

Sulfonic acid functionalized SBA‐15 (SBA‐Pr‐SO₃H) as a new nanoporous solid acid catalyst was applied in the green one‐pot synthesis of spirooxindole‐4H‐pyrans via condensation of isatins, malononitrile or methyl cyanoacetate or ethyl cyanoacetate, and 4‐hydroxycoumarin in water solvent. SBA‐Pr‐SO₃H was proved to be an efficient heterogeneous nanoporous solid acid catalyst with a pore size of 6 nm that could be easily handled and removed from the reaction mixture by simple filtration and can be recovered and reused for several times without any loss of activity. The significant merits of present methodology are its simplicity, short reaction time, good yields, and environmentally benign mild reaction condition as water was used as a green solvent.     

A New Reaction of Isatin,Cyclic 1,3‐Diketone,and 2‐Cyanoacetamide: A Four‐Component Synthesis of Spirooxindoles

A novel reaction of isatins, 2‐cyanoacetamide, and cyclic 1,3‐diketones in ethanol was reported. The reaction gave the unexpected spirooxindole ethyl carboxylates in excellent yields and the spirooxindole carboxamide was not observed.     

Synthesis of Spirooxindoles through Cyclocondensation of Isatin and Cyclic 1,3‐Diones

A simple, clean, and efficient method for the synthesis of spirooxindole derivatives via condensation of isatin with enolizable cyclic β‐diketones has been developed. The use of water as a solvent allows avoiding the use of toxic organic solvents, which makes this reaction safe and environmentally friendly. The mechanism of the condensation reaction has been investigated using first‐principles‐based density functional theory calculations.     

Synthesis and characterization of MgO nanoparticles supported on ionic liquid‐based periodic mesoporous organosilica (MgO@PMO‐IL) as a highly efficient and reusable nanocatalyst for the synthesis of novel spirooxindole‐furan derivatives

The synthesis and catalytic application of a novel MgO containing periodic mesoporous organosilica with ionic liquid framework (MgO@PMO‐IL) is described. The prepared MgO@PMO‐IL was characterized by Fourier transform‐infrared spectroscopy, N₂ adsorption/desorption, transmission electron microscopy, field emission‐scanning electron microscopy, thermogravimetric and inductively coupled plasma analyses. This nanocatalyst was successfully applied as a highly efficient and recoverable catalyst for the synthesis of novel spirooxindole‐furan derivatives via the three‐component reaction of 1,3‐dicarbonyl compounds, N‐phenacyl pyridinium salts and isatin derivatives. The products were achieved in high to excellent yields with a simple work‐up procedure and short reaction times, and the catalyst could be recovered through a simple filtration process and successfully reused seven times without any significant decrease in its efficiency.     

Construction of Spirocyclic Oxindoles through Regio‐ and Stereoselective [3+2] or [3+2]/[4+2] Cascade Reaction of α,β‐Unsaturated Imines with 3‐Isothiocyanato Oxindole

On the basis of asymmetric regioselective [3+2] or [3+2]/[4+2] cascade reaction of 3‐isothiocyanato oxindoles with C=C and C=N bonds of α,β‐unsaturated methanesulfonamides, diversified S‐containing heterocyclic spirooxindole derivatives could be obtained in high yields along with good to excellent diastereo‐ and enantioselectivities under mild conditions in the presence of cinchona alkaloid‐derived organocatalysts.     

A mild and green chemistry approach for the synthesis of symmetrical spirooxindole derivatives

A simple and eco-friendly synthesis of the biologically important spirooxindole scaffold was done by the reaction of isatin with activated pyrazolones in the presence of a catalytic amount of p-toluenesulfonic acid in water at room temperature. A variety of symmetrical spirooxindole derivatives were obtained with excellent yields within short reaction time. This method is of great value because of its environmentally benign character, high yield, and easy handling.     

An efficient three‐component synthesis of hexahydroquinoline derivatives in ionic liquid

A series of hexahydroquinoline derivatives were synthesized by the three‐component reaction of 5,5‐dimethyl‐3‐aminocyclohex‐2‐enone, aromatic aldehyde, and acyl acetonitrile in ionic liquid without using any catalyst. This protocol has the advantages of easier work‐up, milder reaction conditions, high yields, and environmentally benign procedure. J. Heterocyclic Chem., (2011).     

Organocatalytic Asymmetric Cascade Reactions of 7‐Vinylindoles: Diastereo‐ and Enantioselective Synthesis of C7‐Functionalized Indoles

The first catalytic asymmetric cascade reaction of 7‐vinylindoles has been established by the rational design of such substrates. Cascade reactions with isatin‐derived 3‐indolylmethanols in the presence of a chiral phosphoric acid derivative allow the diastereo‐ and enantioselective synthesis of C7‐functionalized indoles as well as the construction of cyclopenta[b]indole and spirooxindole frameworks (all >95:5 d.r., 94–>99 % ee). This approach not only addresses the great challenge of the catalytic asymmetric synthesis of C7‐functionalized indoles, but also provides an efficient method for constructing biologically important cyclopenta[b]indole and spirooxindole scaffolds with excellent optical purity. Investigation of the reaction pathway and activation mode has suggested that this cascade reaction proceeds through a vinylogous Michael addition/Friedel–Crafts process, in which dual H‐bonding activation of the two reactants plays a crucial role.     

One‐Pot Three‐Component Synthesis of Spirooxindoles Catalyzed by Hexamethylenetetramine in Water

A simple, convenient, and multicomponent strategy for synthesis of spirooxindole derivatives has been developed. This strategy provides a rapid access to construct a diversity‐oriented library of spirooxindoles by using three simple and readily available isatin, malononitrile or cyanoacetic ester, and 1,3‐dicarbonyl compound catalyzed by hexamethylenetetramine in water.     

Catalytic Asymmetric 1,2‐Addition of α‐Isothiocyanato Phosphonates: Synthesis of Chiral β‐Hydroxy‐ or β‐Amino‐Substituted α‐Amino Phosphonic Acid Derivatives

α‐Amino phosphonic acid derivatives are considered to be the most important structural analogues of α‐amino acids and have a very wide range of applications. However, approaches for the catalytic asymmetric synthesis of such useful compounds are very limited. In this work, simple, efficient, and versatile organocatalytic asymmetric 1,2‐addition reactions of α‐isothiocyanato phosphonate were developed. Through these processes, derivatives of β‐hydroxy‐α‐amino phosphonic acid and α,β‐diamino phosphonic acid, as well as highly functionalized phosphonate‐substituted spirooxindole, can be efficiently constructed (up to 99 % yield, d.r. >20:1, and >99 % ee). This novel method provides a new route for the enantioselective functionalization of α‐phosphonic acid derivatives.     

The reaction of (N‐isocyanimino) triphenylphosphorane with (E)‐3‐aryl‐2‐ propenoic acid derivatives: One‐pot synthesis of 2‐[(E)‐2‐aryl‐1‐ethenyl]‐1,3,4‐oxadiazoles via intramolecular aza‐Wittig reaction

The reaction of (E)‐3‐aryl‐2‐propenoic acid derivatives with (N‐isocyanimino) triphenylphosphorane proceeds smoothly at room temperature to afford the corresponding 2‐[(E)‐2‐aryl‐1‐ethenyl]‐1,3,4‐oxadiazole via an intramolecular aza‐Wittig reaction in good yields under neutral conditions. The structures of the products were deduced from their IR, ¹H NMR, and ¹³C NMR spectra and mass spectrometry. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:612–616, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20701     

Efficient synthesis of 4‐heteroaryl‐substituted triphenylamine derivatives via a ligand‐free Suzuki reaction

This paper reports an efficient synthesis of 4‐heteroaryl‐substituted triphenylamine derivatives via the palladium‐catalyzed Suzuki reaction of heteroaryl halides with 4‐(diphenylamino)phenylboronic acid in ethylene glycol under ligand‐free and aerobic conditions. These derivatives are important structural motifs for use in dye‐sensitized solar cells and organic electroluminescence materials. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of 5‐aryl and 5‐amidocamptothecins

A variety of 5‐aryl‐(20S)‐camptothecin derivatives were synthesized by the reaction of 5‐hydroxy‐(20S)‐camptothecin with aromatic hydrocarbons under Friedel‐Craft reaction conditions in moderate to good yield as diastereomeric pairs. The methodology was then extended for the synthesis of 5‐amido‐(20S)‐camptothecin derivatives by reacting 5‐hydroxy‐(20S)‐camptothecin with alkyl and aryl nitriles under Ritter type reaction conditions. The reaction is presumed to proceed through an iminium ion intermediate under Friedel Craft and Ritter type reaction condition, which is further trapped by nucleophile present in the reaction medium. J. Heterocyclic Chem., 00 , 00 (2011).     

Solvent‐free three‐component synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives catalyzed by ammonium acetate

An efficient synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives via the reaction of aryl aldehyde, tetrahydrothiophene‐3‐one‐1,1‐dioxide and malononitrile or ethyl 2‐cyanoacetate was performed at room temperature catalyzed by ammonium acetate under solvent‐free conditions. Compared with the conventional methods, this protocol features mild reaction conditions, high yields, and eco‐friendliness. J. Heterocyclic Chem., (2011).     

An efficient synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives under catalyst‐free and solvent‐free conditions

A simple, efficient and convenient one‐pot synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives under solvent‐free and catalyst‐free conditions by the reaction of aromatic aldehydes, isatoic anhydride, and ammonium acetate was reported. The advantages of this protocol include short reaction time, mild reaction conditions, easy work‐up, high yields, and environmental friendliness. J. Heterocyclic Chem., (2011).     

Zinc chloride‐catalyzed one‐pot,three‐component synthesis of 5,8‐dihydro‐5,8‐dioxo‐4H‐chromene derivatives

An efficient zinc chloride‐catalyzed one‐pot synthesis of 5,8‐dihydro‐5,8‐dioxo‐4H‐chromene derivatives have been achieved by the reaction of 2,5‐dihydroxy‐6‐undecyl‐1,4‐bezoquinone, cyanothioacetamide, and aromaticaldehyde, in EtOH at room temperature. The structures of the products were characterized by IR, ¹H‐NMR, mass spectra, and elemental analyses. J. Heterocyclic Chem., (2011).     

One‐pot Three‐component Synthesis of Spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] Derivatives Catalyzed by Melamine Trisulfonic Acid

Novel spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] derivatives were prepared by the three‐component reaction of isatins 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine and Meldrum's acid in the presence of a catalytic amount of melamine trisulfonic acid. This protocol provides a simple one‐step procedure with the advantages of easy work‐up, mild reaction conditions and environmentally benign.