Quinone Monoimine Research Articles

Cooperative Rh/Achiral Phosphoric Acid-Enabled [3+3] Cycloannulation of Carbonyl Ylides with Quinone Monoimines: Synthesis of Benzofused Dioxabicyclo[3.2.1]octane Scaffolds.

A cooperative Rh/achiral phosphoric acid-enabled [3+3] cycloaddition of in situ-generated carbonyl ylides with quinone monoimines has been developed. With the ability to build up the molecular complexity rapidly and efficiently, this method furnishes highly functionalized oxa-bridged benzofused dioxabicyclo[3.2.1]octane scaffolds bearing two quaternary centers in good to excellent yields under mild conditions. Moreover, the utility of the current method was demonstrated by gram-scale synthesis and elaboration of the products into various functionalized oxa-bridged heterocycles.

Copper-Catalyzed [3 + 2] Annulation of O-Acyl Oximes with 4-Sulfonamidophenols for the Synthesis of 5-Sulfonamidoindoles and 2-Amido-5-sulfonamidobenzofuran-3(2H)-ones.

A copper-catalyzed [3 + 2] annulation of O-acyl oximes with 4-sulfonamidophenols is developed. The advantage of this method lies in the concurrent double activation of two substrates to form nucleophilic enamines and electrophilic quinone monoimines. The substituent on the α-carbon of O-acyl oxime determines two different reaction pathways, thereby leading to the selective generation of 5-sulfonamidoindoles and 2-amido-5-sulfonamidobenzofuran-3(2H)-ones.

Synthesis of spiropyrans via Ru(II)-catalyzed coupling of 3-aryl-2H-benzo[b][1,4]oxazines with benzoquinones.

An efficient Ru(II)-catalyzed C-H activation-based spiroannulation of benzoxazines with the easily available benzoquinone and N-sulfonyl quinone monoimine has been realized, providing a straightforward strategy to access NH-containing spiropyrans in moderate to good yields with good functional group compatibility. The procedure features atom- and step-economy, mild conditions, and excellent chemoselectivity. Moreover, a catalytically competent five-membered cycloruthenated complex has been isolated.

Highly enantioselective [3+2] annulation of 4-amino-isoxazoles with quinone monoimines to access structurally diverse isoxazoline fused dihydrobenzofurans and antifungal evaluation

The first catalytic enantioselective [3+2] cyclization between 4-amino-isoxazoles and quinone monoimines was achieved by using a chiral phosphoric acid catalyst. This transformation afforded a series of isoxazoline fused dihydrobenzofuran derivatives with two sequential chiral centers in high yields and outstanding enantioselectivities. The absolute configuration of the title compounds was determined by X-ray crystal structure analysis. The subsequent application of the obtained products displayed good antifungal activity against five plant pathogenic fungi further demonstrates the versatility of this transformation.This approach provided an excellent alternative strategy for the synthesis of corresponding bioactive molecules containing an isoxazoline fused dihydrobenzofurans skeleton.

Gold-Catalyzed Alkyne Multifunctionalization through an Oxidation-Oxyalkylation-Aryloxylation Sequence.

A gold-catalyzed oxidative three-component reaction of terminal alkynes with alcohols and quinone monoimines has been disclosed, affording α-ketoacetals in good to excellent yields. By using quinone monoimines as electrophiles for the interception of the in situ generated gold enolate intermediate, this one-pot process provides an unprecedented method for the polyfunctionalization of terminal alkynes through an oxidation-oxyalkylation-aryloxylation sequence, installing three oxygen atoms on the C-C triple bond.

NEW ACID-BASIC INDICATORS: RESEARCH USING A SMARTPHONE

Modern cameras, desktop scanners, smartphones allow not only registering an image, but also determining its color characteristics. That allows us to quickly, objectively and automatically determine the color characteristics of colored samples in acid-base titration, because there is a significant error at visually determining the pH range of the color transition. In analytical chemistry the characteristics of acid-base indicators are very important, in particular their pH transition interval. But the disadvantage of most indicators is the wide range of color transition: from 1 to 3 pH units. The aim of this work is to find new acid-base indicators that change color in an alkaline environment and have a narrow pH range of the color transition. We have developed the apparatus and technique of convenient and highprecision simultaneous determination of the pH of the medium and the color of the acidbase indicators. In acid-base titration the PH measurements were performed with a combined glass electrode AD1131 by рН-meter AD1000. The color transition was determined with help of a smartphone with the subsequent processing of the results by computer software. The color characteristics were measured for each channel of the RGB model in the range from 0 to 255. Our apparatus is small and mobile, and allows us simultaneously to measure the pH of the medium and accurately to determine the color characteristics. As a result, we can construct graphical dependencies of color on pH for each channel of the RGB model. We found the N-arylsulfonyl-2-aroylamido-1,4-benzo(naphto)quinone monoimines and 2,5-dibenzoylamido-1,4-benzoquinone are good acid-base indicators. They “work” in the pH range from 8.82 to 11.35 and have a very narrow color transition interval from 0.10 to 0.61. Solutions of these compounds in an alkaline medium have bright intense colors due to formation of mesomeric ions. That allows using of these indicators in the titration of weak acids with strong bases and vice versa by the method of neutralization.

Tandem Reaction of Phenyl α‐Cyano‐α‐arylacetates with Quinone Monoimines

AbstractA tandem reaction of phenyl α‐cyano‐α‐arylacetates with quinone monoimines was presented, which allowed for the synthesis of various 2‐aminobenzofuran derivatives in low to moderate yields. This method is applicable to a series of phenyl α‐cyano‐α‐arylacetates with various aryl groups and quinone monoimines with different substituents. In addition, a pausible mechanism was proposed.

Tandem Conjugate Addition/Aromatization/Acyl Transfer Reaction between 3‐Aryl‐2‐nitropropanoates and Quinone Monoimines

AbstractA tandem conjugate addition/aromatization/acyl transfer reaction between 3‐aryl‐2‐nitropropanoates and quinone monoimines was described. In the presence of NMM, the reaction proceeded smoothly to give various 1,2‐diarylnitroethanes in low to good yields. The structure of one product was determined by an X‐ray crystal structural analysis. Accordingly, a plausible reaction mechanism was proposed.

Enantioselective [3 + 2] annulation of 3-hydroxymaleimides with quinone monoimines

Enantioselective [3 + 2] annulation of 3-hydroxymaleimides with quinone monoimines provided a large variety of succinimide fused indolines in moderate to good yields with moderate to good enantioselectivities.

ACYLAMINATION OF N-ARYLSULPHONYL-1,4-BENZOQUINONE MONOIMINES

The acylamination of the N-substituted 1,4-benzoquinonimines is a simple method to enter the acylaminogroup into the quinoid ring. In this way, the final product with the unchangeable quinoid structure can be obtained in one stage. The acylamination was carried out as reaction of N-arylsulfonyl-1,4-benzoquinone monoimines and N-chloramide of 4-methylbenzoic acid. The starting N-arylsulfonyl-1,4-benzoquinone monoimines contained both donor and acceptor substituents in the quinoid ring. As a result, 2-(4-methylbenzoyl)amino-N-(4-methylphenyl) sulfonyl-1,4-benzoquinone monoimines were obtained. These monoimines are the products of substitution of the hydrogen atom of the free C=C bond of the quinoid ring of the starting quinone monoimine by the acylamino group. The nature of the substituent in the quinoid ring of the starting N-arylsulfonyl-1,4-benzoquinone monoimines does not influence on the reaction direction. The direction of the reaction depends on the first stage, and this reaction can be regarded as a 1,4-addition. The possibility of this reaction is determined by the steric factor. The same 2-(4-methylbenzoyl)amino-N-(4-methylphenyl)sulfonyl-1,4-benzoquinone monoimines were obtained in reaction of N-arylsulfonyl-1,4-benzoquinone monoamines with O-(4-methyl)benzoylbenzhydroxamic acid in the presence of potassium acetate. The first stage of this reaction is the formation of an anion of hydroxamic acid under the action of acetate anion. Thereafter, the anion is added to the free C=C bond of the quinoid ring. formation of the final product. The PASS program was used to analyze the potential biological activities of the synthetic compounds. All products were found to be inhibitory to the enzymes Glutamyl endopeptidase II, Insulysin, Hexokinase, and Omptin.

RЕACTION OF O-ARYL(METHYL)SULFONATES OF 1,4-QUINONE MONOOXIMES WITH HYDRAZINES

Aroylhydrazones contain the active pharmacophore group >C=N–NH–CO–. These compounds show antimicrobial, antibacterial, and even anticancer activity. In addition, aroylhydrazones are synthons in the synthesis of various heterocyclic compounds. The purpose of this work is to define the features of the reaction of aryl(benzoyl)hydrazines with O-sulfonates of 1,4-quinone monooxime and to synthesize the benzoquinone hydrazones based on them. In the result of reaction of 1,4-quinone monoxime O-sulfonates with phenylhydrazine the p-tolyl(methyl)sulfates of the corresponding aminophenols were obtained. Subsequent treatment of these sulfates with water and acidification led to sulfate destruction and formation of a mixture of the corresponding aminophenol and p-tolyl(methyl)sulfate acid. We did not obtain 1,4-benzoquinone hydrazones. Thus, in the reaction of 1,4-quinone monoxime O-sulfonates with phenylhydrazine, the first stage is the N–O bond break with reduction of quinoid ring, and this redox process is due to the high basicity of aryl hydrazines. The aroylhydrazones of 1,4-benzoquinone were obtained only in the reaction of aroylhydrazines with 1,4-quinone monoxime O-sulfonates, containing two alkyl substituents in the both orthopositions to the carbonyl group of the quinoid ring. The first step of this reaction is also the =N–O– bond breaking of the starting sulfonates and formation of corresponding quinone imines. 2,6-Disubstituted quinone monoimines have less redox potential, and aroylhydrazines are less basic than arylhydrazines, therefore, the formation of corresponding aroylhydrazones of 1,4-benzoquinone is possible. The variation of the substituent attached to the oxygen atom of the starting 1,4-quinone monooxime O-sulfonates (MeSO2 or Ts) does not affect the reaction route.

Enantioselective dearomative [3+2] annulation of 5-amino-isoxazoles with quinone monoimines.

The first enantioselective dearomative [3+2] annulation of 5-amino-isoxazoles with quinone monoimines was realized using a chiral phosphoric acid as catalyst. Various novel (bridged) isoxazoline fused dihydrobenzofurans bearing two continuous quaternary stereocenters were achieved in moderate to good yields (up to 94%) with moderate to good enantioselectivities (up to 98% ee). The absolute configurations of two products were assigned by X-ray crystal structural analyses and a plausible reaction mechanism was proposed.

Unprecedented Tandem Conjugate Addition/C‐O Ester Migration of α‐Cyano Arylacetates with a Quinone Monoimine

AbstractAn unprecedented conjugate addition/C−O ester migration of α‐cyano arylacetates with a quinone monoamine was presented, which allowed for the synthesis of various 2,2‐diarylacetonitriles in moderate to quantitative yields. This method is applicable to a series of α‐cyano arylacetates with different aryl groups. Moreover, in order to demonstrate the synthetic utility of this transformation, 2‐(cyano(phenyl))‐4‐(4‐methylphenylsulfonamido)ethyl carbonate was subjected in hydrogenation to generate a 2,2‐diarylethylcarbamate.

Synthesis of Novel Pterocarpen Analogues via [3 + 2] Coupling‐Elimination Cascade of α,α‐Dicyanoolefins with Quinone Monoimines

By employing triethylamine as a catalyst, [3 + 2] coupling‐elimination cascade of α,α‐dicyanoolefins with quinone monoimines was realized. The reactions afforded various novel pterocarpen analogues with generally moderate yields (up to 75%). In addition, a plausible reaction mechanism was proposed.

Enantioselective Arylation of 3-Carboxamide Oxindoles with Quinone Monoimines and Synthesis of Chiral Spirooxindole-benzofuranones

A highly enantioselective arylation of 3-carboxamide oxoindoles with quinone monoimines is described. Various 3-aryl-3-carboxamide oxindoles with an all-carbon quaternary center were obtained in moderate to good yields (up to 99%) with moderate to good enantioselectivities (up to 98%) in the presence of a bifunctional thiourea-tertiary amine catalyst. The absolute configuration of one product was determined by an X-ray crystal structural analysis and the absolute configurations of the other products can be assigned by analogy. Moreover, several chiral spirooxindole-benzofuranones were synthesized from the 3-aryl-3-carboxamide oxindoles in moderate yields with moderate to good enantioselectivities.

Permanent porous hydrogen-bonded frameworks with two types of Br\xf8nsted acid sites for heterogeneous asymmetric catalysis

The search for porous materials with strong Brønsted acid sites for challenging reactions has long been of significant interest, but it remains a formidable synthetic challenge. Here we demonstrate a cage extension strategy to construct chiral permanent porous hydrogen-bonded frameworks with strong Brønsted acid groups for heterogeneous asymmetric catalysis. We report the synthesis of two octahedral coordination cages using enantiopure 4,4’,6,6’-tetra(benzoate) ligand of 1,1’-spirobiindane-7,7’-phosphoric acid and Ni4/Co4-p-tert-butylsulfonylcalix[4]arene clusters. Intercage hydrogen-bonds and hydrophobic interactions between tert-butyl groups direct the hierarchical assembly of the cages into a permanent porous material. The chiral phosphoric acid-containing frameworks can be high efficient and recyclable heterogeneous Brønsted acid catalysts for asymmetric [3+2] coupling of indoles with quinone monoimine and Friedel-Crafts alkylations of indole with aryl aldimines. The afforded enantioselectivities (up to 99.9% ee) surpass those of the homogeneous counterparts and compare favorably with those of the most enantioselective homogeneous phosphoric acid catalysts reported to date.

Enantioselective α‐Arylation of Cyclic β‐Ketoamides with a Quinone Monoimine

AbstractA facile and direct method for the construction of enantioenriched α‐arylated quaternary β‐ketoamides was developed. By employing a chiral bifunctional thiourea‐tertiary amine as catalyst, enantioselective α‐arylation of cyclic β‐ketoamides with a quinone monoimine proceeded smoothly to afford various α‐arylated quaternary β‐ketoamides in good yields (up to 97%) with moderate to good enantioselectivities (up to 85% ee). Generally, benzo six‐membered cyclic β‐ketoamides exhibited better enantioselection than benzo five‐membered cyclic β‐ketoamides.

Synthesis of benzannulated spiroketals with gold-catalyzed cycloisomerization/spiroketalization cascade

An unprecedented gold-catalyzed cascade reaction of alkynyl alcohol and quinone monoimines to diverse 5,5-benzannulated spiroketals has been successfully developed.

Kinetics and mechanism of the chain reaction between N-phenyl-1,4-benzoquinone monoimine and thiophenol

The kinetics of the reaction between N-phenyl-1,4-benzoquinone monoimine (quinone monoimine) and thiophenol is studied in chlorobenzene at 343 K. The reaction has the same mechanism proposed earlier for a similar reaction involving N,N'-diphenyl-1,4-benzoquinone diimine (quinone diimine). This mechanism has two paths: chain and nonchain. An important difference between the kinetics of the two reactions is the apparent reversible nature of the chain reaction in the quinone monoimine + thiophenol system. This nature reveals itself when the concentrations of thiophenol are comparable to or slightly higher than the concentrations of quinone imine. In light of this, kinetic research is conducted under conditions where the concentrations of thiophenol are significantly higher than those of quinone monoimine, allowing us to simplify the kinetic features and obtain interpretable data. The rate constants of the reaction’s elementary steps are estimated and found to be three to five times lower for the reaction involving quinone monoamine than for the one involving quinone diimine. Both reactions have relatively short chains whose lengths do not exceed several tens of units.

1,3-dipolar cycloaddition of diazomethane to quinoid derivatives of pyrido[1,2-a]benzimidazole

Reactions of diazomethane with quinone mono(di)imines and methylidene quinone imines of pyrido[1,2-a]benzimidazole series occurs by the route of 1,3-dipolar cycloaddition and leads to the formation of quinoid compounds, in particular, previously unknown heterocyclic structures of indazolo[7',6':4,5]imidazo-[2,1-j]quinoline, indazolo[7',6':4,5]imidazo[2,1-e]acridine, indazolo[4',5':4,5]imidazo[2,1-j]quinoline, and indazolo[4',5':4,5]imidazo[2,1-e]acridine.