Facile synthesis of 3,3-di(heteroaryl)indolin-2-one derivatives catalyzed by ceric ammonium nitrate (CAN) under ultrasound irradiation

Ceric ammonium nitrate efficiently catalyzes the reaction of isatin with indoles under sonic waves to afford symmetrical 3,3-di(indolyl)indolin-2-ones in excellent yields, as well as the reaction of 3-hydroxy-3-indolylindolin-2-ones with indoles, pyrrole to afford the corresponding adducts in excellent yields, which provides an efficient route to the synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-one derivatives, respectively.     

An Efficient and Clean Synthesis of Symmetrical and Unsymmetrical 3,3-Di(indolyl)Indolin-2-ones Using KSF

A facile and convenient protocol was developed for the synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-ones in low reaction times (22–35 min) and high yields (85–95%) using KSF as an efficient recyclable heterogeneous catalyst.     

Efficient synthesis of bis-indolyloxindoles from (phenylimino)indolin-2-ones and 1<Emphasis Type="Italic">H</Emphasis>-indole catalyzed by <Emphasis Type="Italic">p</Emphasis>-toluenesulfonic acid

p-Toluenesulfonic acid (p-TSA) efficiently catalyzed the reaction of (phenylimino)indolin-2-ones with 1H-indole in dichloromethane at room temperature to afford 3,3-di(indolyl)indolin-2-ones in 2-3 min with high yields.     

Facile Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones Catalyzed by Ceric Ammonium Nitrate (CAN) under Ultrasound Irradiation

Indole fragment is featured widely in a wide variety of pharmacologically and biologically active compounds.[1] The 3,3-bis(3-indolyl)oxindole has been shown to possess antibiotic activities against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. [2] As a continue of our work on the synthesis of indole derivates such as bis(indolyl)methanes,[3]we describe an ultrasound-accelerated reaction of isatin 1 with indoles 2 using a catalytic amount of ceric ammonium nitrate (CAN), which provides an efficient route to the synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones.     

Rapid and Efficient Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-yl)-2H-acenaphthen-1-ones Catalyzed by p-TSA

An efficient synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones and 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones via a reaction of various isatins or acenaphthenequinone with indoles in the presence of p-methylbenzene sulfonic acid (p-TSA) in CH₂Cl₂ at room temperature is described. The advantages of this method include good reaction yield, simple workup procedure, and mild reaction condition.     

Synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-ones under controlled catalysis of ionic liquids

Three ionic liquids, [BMIM][BF₄] doped with 60 mol % of LiCl ([BMIM][BF₄]-LiCl), N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT), and N,N,N,N-tetramethylguanidinium triflate (TMGT_f) were found useful as catalyst solvents for controlled 3-indolylation of isatins. Our investigation revealed that the reaction between isatin and indoles in [BMIM][BF₄]-LiCl or TMGT_f media stops at the step of addition of the two components providing 3-indolyl-3-hydroxyindolin-2-ones while the ionic liquid TMGT runs the reaction further through accompanying Friedel-Crafts substitution to afford symmetrical 3,3-di(indol-3-yl)indolin-2-ones. To take advantage of the difference between the effects of these ionic liquids on the reaction progress, we planned a two-step protocol for the efficient synthesis of unsymmetrical 3,3-di(indol-3-yl)indolin-2-ones.     

Gold(I)-catalyzed sequential cycloisomerization/bis-addition of o-ethynylanilines: an efficient access to bis(indolyl)methanes and di(indolyl)indolin-2-ones

An efficient synthesis of bis(indolyl)methanes and di(indolyl)indolin-2-ones has been developed by a sequential approach involving gold(I)-catalyzed cycloisomerization/bis-addition of o-ethynylanilines with various aldehydes and isatins, respectively. This methodology opens clean and synthetically competitive alternative to the already established procedures of the synthesis of bis(indolyl)methanes and di(indolyl)indolin-2-ones.     

Catalyst-free straightforward synthesis of 3-cyano-3-arylamino-2-oxindoles through hydrocyanation with benzoyl cyanide

The effective hydrocyanation of 3-(arylimino)indolin-2-ones with benzoyl cyanide under catalyst-free condition at room temperature to synthesize 3-cyano-3-arylamino-2-oxindoles is described. This protocol benefits from low toxicity, inexpensive, and easy-to-handle cyanating agent, no catalysts, no additives, mild conditions, good substrate tolerance, and simple work-up procedure. This reaction successfully offers an alternative to structurally diverse 3,3-disubstituted oxindoles.     

Water-Promoted Synthesis of 3,3′-Di(indolyl)oxindoles

The reaction of isatin and indoles in refluxing water/ethanol (7:3) affords 3,3′-di(indolyl)oxindoles in excellent yields.     

CuI-catalyzed highly regioselective CH functionalization of indoles using indole-3-tosylhydrazones as carbene precursor: An efficient synthesis of 3,3-bis(indolyl)methane derivatives

Herein, we have developed a novel approach for synthesizing symmetrical and unsymmetrical 3,3-bis(indolyl)methane derivatives via CuI-catalyzed CH functionalization of indole using indole-3-tosylhydrazones as carbene precursor. This procedure works well with different substitutions such as NO₂, Br, CH₃ and OMe on indole or indole-3-tosylhydrazones and features high regioselectivity for C-3 functionalization over the C-1 and N-1 positions. Further, we have also revealed the feasibility of this protocol in a one-pot fashion starting from indole-3-carboxyaldehyde.     

Construction of C2-Spirocyclopropyl-Indolin-3-Ones through Base-Promoted [2+1] Annulation Reaction of Indolin-3-ones with Bromosulfonium Salts

A simple base-promoted [2+1] annulation of indolin-3-ones and bromosulfonium salts has been developed in this article. This strategy uses simple and easily prepared indolin-3-ones 1 as C1 synthons and bromosulfonium salts 2 as C2 synthons under mild reaction conditions, and 33 examples of C2-spirocyclopropyl-indolin-3-ones were obtained with up to 99 % yield and >20 : 1 dr.     

Synthesis of novel functionally substituted pyridazines and oxazines

Acetone 1,3-di(phenylhydrazone) reacts with arylidenemalononitriles in the presence of piperidine to give the coressponding 3,3′-carbonylbispyridazine derivatives. Under the same reaction conditions dioxime reacts with arylidenemalononitriles to give the corresponding 3,3′-carbonylbis-1,2-oxazines. Dioxime reacts with primary aromatic amines and formalin in a molar ratio of 1:1:2 to give 1-arylidene-3,5-dihydroxyimino-piperidine-4-ones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1223–1229, August, 2008.     

Syntheses of spiro[indazole-3,3′-indolin]-2′-ones and spiro[indazole-3,3′-indolin]-2′-imines via 1,3-dipolar cycloadditions of arynes and studies on their isomerization reactions

A 1,3-dipolar cycloaddition reaction of arynes with 3-diazoindolin-2-ones under mild conditions in excellent yields has been developed, which allows facile access to a library of labile spiro[indazole-3,3′-indolin]-2′-ones. Spiro[indazole-3,3′-indolin]-2′-imines could be obtained as well following the same protocol. The isomerization reaction of spiro[indazole-3,3′-indolin]-2′-ones under thermal or acidic conditions has been efficiently achieved to afford a wide range of indazolo-[2,3-c]quinazolin-6(5H)-ones and the one-pot synthesis of indazolo-[2,3-c]quinazolin-6(5H)-ones from arynes and 3-diazoindolin-2-ones is also described. Whereas, spiro[indazole-3,3′-indolin]-2′-imines could not undergo the same rearrangement.     

An Imidazoline–Aminophenol (IAP) Nickel Catalyst: Structure and Catalytic Activity in the Enantioselective 1,4‐Addition of 3′‐Indolyl‐3‐Oxindoles to Nitroethylene

The structure of a nickel complex of imidazoline–aminophenol (IAP) prepared from IAP with Ni(OAc)₂ was elucidated as cis‐bis(imidazolineaminophenoxide) [Ni(IAP)₂]. The [Ni(IAP)₂] complex smoothly promoted catalytic asymmetric 1,4‐addition of 3′‐indolyl‐3‐oxindole to nitroethylene to provide chiral mixed 3,3′‐bisindoles with high enantioselectivities. Mechanistic studies using ESI‐MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)₂] to generate the Ni–enolate of 3′‐indolyl‐3‐oxindole. From the optically active 3,3′‐mixed indole adduct, biologically important 3′‐indolyl‐3‐pyrrolidinoindoline was successfully synthesized in a three‐step reaction sequence.     

B(C6F5)3-Catalyzed Aza-Friedel–Crafts Reaction of Indolizines with 2-Aryl-3H-indol-3-ones

A Friedel–Crafts reaction of indolizines with 2-aryl-3H-indol-3-ones catalyzed by B(C₆F₅)₃ is described. This protocol gives access to indolizine derivatives that are valuable building blocks in synthetic and pharmaceutical chemistry. The reaction proceeds under mild conditions, affording various C2-quaternary indolin-3-ones based on indolizine with high yields and regioselectivities. Moreover, the synthetic transformations of the target products were realized by N-methylation and trifluoromethane sulfonation.     

One-pot multicomponent synthesis and antimicrobial evaluation of novel tricyclic indenopyrimidine-2-amines

The synthesis of novel tricyclic indenopyrimidine-2-amines from 3,3-dimethyl-/3-methyl-2H-indanones has achieved by base-catalyzed one-pot three-component reaction. The desired products are formed within 10 hours after addition at reflux temperature. This multicomponent approach offers a viable protocol for the construction of indenopyrimidine-2-amines in single-step without the isolation of the intermediates 3,3-dimethyl/3-methyl-2-(4-substituted benzylidene)-2,3-dihydro-1H-inden-1-ones. All the synthesized compounds have been screened for antimicrobial activity and some of the derivatives show comparable activity against bacterial and fungal isolates.     

A method for synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones with one-carbon ring expansion and its application to a formal synthesis of racemic 1-desoxyhypnophilin

A method for synthesis of 2-cyanobicyclo[3.3.0]oct-1-en-3-ones and 2-substituted bicyclo[3.3.0]oct-1-en-3-ones was developed by assembly of three components, cyclobutanones, chloromethyl p-tolyl sulfoxide, and nitriles, with one-carbon ring expansion of the cyclobutane ring. As an application of this method, a formal synthesis of 1-desoxyhypnophilin in racemic form was performed starting from 3,3-di(phenylthiomethyl)cyclobutanone.     

The transient-chelating-group-controlled stereoselective Rh(i)-catalyzed silylative aminocarbonylation of 2-alkynylanilines: access to (Z)-3-(silylmethylene)indolin-2-ones

A new method involving mild acryl transient-chelating-group-controlled stereoselective Rh(i)-catalyzed silylative aminocarbonylation of 2-alkynylanilines with CO and silanes is presented for producing (Z)-3-(silylmethylene)indolin-2-ones. Upon using an acryl transient chelating group, 2-alkynylanilines undergo an unprecedented alkyne cis-silylrhodation followed by aminocarbonylation to assemble (Z)-3-(silylmethylene)indolin-2-ones. Mechanistic studies show that acryl transient chelating effects result in the key alkyne cis-silylrhodation process.

Transient-chelating-group-controlled stereoselective rhodium(I)-catalyzed silylative aminocarbonylation of 2- alkynylanilines with CO and silanes toward (Z)-3-(silylmethylene)indolin-2-ones is presented.     

Microwave assisted synthesis of indole-annulated dihydropyrano[3,4-c]chromene derivatives via hetero-Diels-Alder reaction

An efficient two-step synthesis of indole-annulated dihydropyrano[3,4-c]chromene derivatives is achieved via Knoevenagel condensation of O-propargylated salicylaldehyde derivatives with indolin-2-ones followed by a microwave-assisted intramolecular-hetero-Diels-Alder reaction of the resulting (Z)-3-(2-(prop-2-ynyloxy)benzylidene)indolin-2-ones in the presence of 20 mol % CuI in acetonitrile.     

General synthesis of mono-, di-, and tri-acetylated indoles from indolin-2-ones

Having developed the one-pot triacetylation of indolin-3-ones, we have now devised a simple two-step reaction sequences to produce di- and mono-acetylated indoles from indolin-2-ones. The indolin-2-ones were first subjected to acetylation in the presence of acetic anhydride and a catalytic amount of N,N-dimethylaminopyridine to give 2-acetoxy-1,3-diacetylindoles. Subsequently, an enzyme-assisted deacetylation resulted in the chemoselective deprotection of the acetoxy group to produce 1,3-diacetyl-2-hydroxyindoles. However, a chemical deacetylation of 2-acetoxy-1,3-diacetylinoles under mild basic or acidic conditions resulted in the formation of 3-acetyl-2-hydroxyindoles.