Synthesis and Configuration of 6-Arylidene-2-furfurylidenecyclohexanones

6-Arylidene-2-furfurylidenecyclohexanones were obtained by the condensation of cyclohexanone with aldehydes of the aromatic and furan series under conditions of base or acid catalysis. The effect of substituents in the aromatic ring on the activity of the initial aldehyde was studied. According to data from the IR spectra, the obtained ketones exist in the form of trans,trans isomers.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 191–195, February, 2005.     

Synthesis of Derivatives of 1-(9-Alkyl-9H-carbazol-3-yl)-4-carboxy-2-pyrrolidinones

Derivatives of 1-(9-alkyl-9H-carbazol-3-yl)-4-carboxy-2-pyrrolidinones (methyl esters, hydrazides) were synthesized. The condensation of the synthesized hydrazides with aromatic aldehydes, acetylacetone, and acetoacetic ester was studied. Structure of the obtained compounds was confirmed by IR and NMR spectroscopy. The specific characteristics of the substituents are discussed.     

The palladium catalyzed thienylation of allylic alcohols with 2- and 3-bromothiophenes and their derivatives

Pd catalyzed reaction of allylic alcohols with 2-bromothiophene provides 3-(2'-thienyl)aldehydes or ketones selectively together with the small amounts of 2-(2'-thienyl)aldehydes and ketones. Similarly 3-(3'-thienyl)-aldehydes or ketones were obtained selectively from allylic alcohols and 3-bromothiophene. The reactivity and regioselectivity largely depend on the solvents, additives, and the structure of allylic alcohols. Generally aprotic dipolar solvent such as HMPA and DMF gave the most satisfactory results. 2-Thienyl iodide showed somewhat higher reactivity than 2-thienyl bromide. 2-Thienyl chloride was unreactive. Sodium iodide and/or triphenyl-phosphine were very effective as the cocatalysts especially for the reactions to give aldehydes. This thienylation reaction was also applicable to 2-bromothiophenes with a wide variety of substituents at 5-position. The synthetic utility of this catalytic reaction has been illustrated by the synthesis of 9-oxo-trans-2-decenoic acid (Queen substance).     

Versatility of the Biginelli reaction: Synthesis of new biphenyl dihydropyrimidin-2-thiones using different ketones as building blocks

A multi-component synthesis of biphenyl dihydropyrimidin-2-thiones from 1-phenylthiourea, aldehydes and ketones or di-ketones has been demonstrated. The reaction proceeded well for aldehydes with electron donor or acceptor substituents under mild conditions.     

2-Benzopyrylium salts

The reaction of alkyl and aryl benzyl ketones with acetals of aliphatic, aromatic, and heterocyclic aldehydes in the presence of triphenylmethyl perchlorate leads to 2-benzopyrylium perchlorates with substituents in positions 1, 3, 6, and 7. The influence of substituents in the benzyl ketones and the acetals on the ease of formation of the salts has been studied. The mechanism of the reaction is discussed.For communication XII, see [2].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 881–884, July, 1973.     

Chemoselectivity in the Reaction of 2‐Diazo‐3‐oxo‐3‐phenylpropanal with Aldehydes and Ketones

The chemoselectivity in the reaction of 2‐diazo‐3‐oxo‐3‐phenylpropanal ( 1 ) with aldehydes and ketones in the presence of Et₃N was investigated. The results indicate that 1 reacts with aromatic aldehydes with weak electron‐donating substituents and cyclic ketones under formation of 6‐phenyl‐4H‐1,3‐dioxin‐4‐one derivatives. However, it reacts with aromatic aldehydes with electron‐withdrawing substituents to yield 1,3‐diaryl‐3‐hydroxypropan‐1‐ones, accompanied by chalcone derivatives in some cases. It did not react with linear ketones, aliphatic aldehydes, and aromatic aldehydes with strong electron‐donating substituents. A mechanism for the formation of 1,3‐diaryl‐3‐hydroxypropan‐1‐ones and chalcone derivatives is proposed. We also tried to react 1 with other unsaturated compounds, including various olefins and nitriles, and cumulated unsaturated compounds, such as N,N′‐dialkylcarbodiimines, phenyl isocyanate, isothiocyanate, and CS₂. Only with N,N′‐dialkylcarbodiimines, the expected cycloaddition took place.     

Preparation of 2,2'-dihydroxytriphenylmethanes using metal phenolates with aromatic aldehydes

The reactions of oxophilic metal phenolates having electron-donating substituents (1a-c) with aromatic aldehydes (2, 3) were selectively condensed at the ortho-position of the starting phenol to afford 2,2'-dihydroxytriphenylmethanes (8-11). This method was also applicable to the preparation of bisphenols (12-17) starting with naphthaldehydes (4, 5) and pyridinecarboxaldehydes (6, 7), but in low yields. In the case of these aldehydes (4-7), satisfactory yields could be obtained by sonication.     

Simple route to meso-substituted trans-A2B2-porphyrins bearing pyridyl units

We have developed a methodology that affords regioisomerically pure trans-A₂B₂-porphyrins bearing pyridyl substituents. The optimal conditions for their synthesis were identified by the modification of known conditions for the reaction of dipyrromethanes with aromatic aldehydes. A total of five new porphyrins were synthesized.     

Synthesis of pyrylium salts and pyridines containing heterocyclic substituents

A method of synthesizing pyrylium salts with heterocyclic substituents in the ring, has been investigated. The synthesis was carried out in two stages: alkaline condensation of aromatic and heterocyclic aldehydes with methyl ketones to give 1, 5-diketones, followed by cyclization to pyrylium salts by treatment with triphenylmethyl perchlorate. Pyridines containing heterocyclic substituents were obtained by treating the pyrylium salts with ammonia.     

Stereochemistry of products of aldol condensation of 2-(3-oxo-1,3-diphenylpropyl)cyclohexanone with aromatic aldehydes

The aldol condensation of various aromatic aldehydes with 2-(3-oxo-1,3-diphenylpropyl)cyclohexanone in CH₂Cl₂ in the presence of TiCl₄-Et₃N at 0°C afforded perhydrochromens with two equatorial and one axial substituents whereas the aldol reaction under base catalysis gave perhydrochromens with equatorial substituents.     

Quinazolines and 1,4-benzodiazepines. LXXXV syntheses of 3-substituted lmidazo[1,5-a] [1,4]benzodiazepines

1,4-Benzodiazepines having a leaving group in the 2-position were condensed with carbanions of 1,3-dicarbonyl compounds. The products obtained were converted to the title compounds by a sequence of steps involving hydrolytic decarboxylation, nitrosation, catalytic hydrogenation and condensation with an orthoester or an amide acetal. Oxidative condensation of the enediamine 12 with a variety of aldehydes also led to imidazo-benzodiazepines with various substituents in the 1-position.     

Chirality Control by Substituents in the Asymmetric Addition of Et_2Zn to Aromatic Aldehydes Catalyzed by cis-(1 R,2S)-2- Benzamidocyclohexanecarboxylic Acid Derived 1,3-Aminoalcohols

A series of novel optically active 1,3‐aminoalcohols based on cis‐(1R,2S)‐2‐benzamidocyclohexanecarboxylic acid and trans‐(1R,2R)‐2‐benzamidocyclohexanecarboxylic acid were synthesized and used in the asymmetric diethylzinc addition to aromatic aldehydes. Not only the enantioselectivity but also the stereochemistry of the product were controlled by the N‐substituents and the substituents on the vicinity carbon to hydroxyl group of the cis‐derivatives.     

Heterocyclic tautomerisms. II. An investigation of the 2-arylbenzothiazoline 2-(benzylideneamino)thiophenol tautomerism. Part 2

The reaction between 4-mercaptoaniline and various aromatic aldehydes was studied as a model system in order to determine which type of substitution on the aryl group in 2-arylbenzothiazolines (1) might give rise to the greatest possible stabilization of the hypothetical 2-(benzylideneamino)thiophenol tautomer (II). Regardless of electronic effect of substituents, most aldehydes reacted with 4-mercaptoaniline to form poly[4-(benzylideneamino)thiophenols] (III). Aromatic aldehydes substituted in the 2 position with the hydroxyl function reacted to form the stable, monomeric 4-(benzylideneamino)thiophenols (IV). This stabilization in the monomeric state is presumed to be due to the hydrogen-bonded nature of these compounds (V). Both monomeric and polymeric compounds reacted with benzalacetophenone in the presence of a basic catalyst in the manner to be expected of the 4-(benzylideneamino)thiophenol structure (IV) yielding correspondingly substituted 1,3-diphenyl-1-[4-(benzylideneamino)phenylthio]-3-propanones (VI).     

Direct synthesis of 2-aryl-1,3-benzoselenazoles by reaction of bis(2-aminophenyl) diselenides with aryl aldehydes using sodium metabisulfite

We present here a general and easy method for the synthesis of several 2-aryl-1,3-benzoselenazoles from the reaction of bis(2-aminophenyl) diselenides with different aryl aldehydes, promoted by the non-toxic inorganic reducing agent sodium metabisulfite (Na₂S₂O₅) in DMSO at 120 °C. This efficient method furnishes in high yields the corresponding 2-aryl substituted 1,3-benzoselenazoles and tolerates a range of substituents at the aryl ring of aldehydes. The use of focused microwave irradiation decreases drastically the reaction time from 48 to 2 h.     

Hetarylethylene derivatives of 2,5-diphenyloxazole

A number of new effective luminophores were synthesized by PO olefination from 2-(4-bromomethylphenyl)-5-phenyloxazole and various heterocyclic aldehydes containing a furan ring. All of the compounds obtained have intense fluorescence in toluene and, depending on the nature of the substituents, the color of the luminescence changes from blue to green. It is shown that chloro, bromo, and methyl substituents have little effect on the spectral-luminescence properties of the compounds obtained, whereas a nitro group causes a decrease in the fluorescence quantum yield.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1616–1618, December, 1977.     

Sterically oriented synthesis and structure of new perphosphorylated resorcinarenes

Tetraarylresorcinarenes in a chair conformation of C_2h symmetry were synthesized by sterically oriented condensation of aromatic aldehydes with resorcinol and 2-methylresorcinol. By further phosphorylation of resorcinarenes with phosphorous amides perphosphorylated derivatives were obtained with rctt configuration of substituents at internuclear methylidene bridges. Structure of these compounds was proved using NMR spectroscopy and X-ray diffraction analysis.     

Synthesis of 2-imino-4-vinyl-2,5-dihydrofuran-3-carboxamides and some their chemical transformations

2-Imino-2,5-dihydrofuran-3-carboxamides containing 2-phenyl- and 2-furylvinyl substituents in position 4 of the furan ring were synthesized by condensation of 2-imino-4-methyl-2,5-dihydrofuran-3-carboxamides with the corresponding aldehydes. Acid hydrolysis of 4-(2-arylvinyl)-2-imino-2,5-dihydrofuran-3-carboxamides gave 4-(2-arylvinyl)-2-oxo-2,5-dihydrofuran-3-carboxamides, and their condensation with malononitrile resulted in the formation of 2-dicyanomethylidene derivatives.     

Synthesis of trans-A2B2-porphyrins bearing phenylethynyl substituents

Efficient and convenient conditions for the preparation of trans-A(2)B(2)-porphyrins bearing two phenylethynyl moieties directly from phenylpropargyl aldehydes and dipyrromethanes of diversified lipophilicity and reactivity have been developed. This new procedure allows the preparation of a library of porphyrins of this architecture with a wide range of substituents. Thanks to the identification of the reagent solubility as one of the key factors influencing the yield of the porphyrinogens, we were able to improve yields to ca. 30%. The scope and limitations of two sets of conditions have been explored. The methodological advantage of this approach is its straightforward access to building blocks and the formation of the porphyrin core in the last step without the need for deprotection of the triple bond or bromination and consecutive coupling reaction, which often demands copper salts to proceed smoothly, especially with electron-deficient alkyne partners. Therefore, it prevents undesired copper porphyrin formation, as well as the need for utilizing expensive alkynes. A two-step method for the preparation of phenylpropargyl aldehydes has also been refined.     

A comparison of ring-chain tautomerism in heterocycles derived from 2-aminobenzenesulfonamide and anthranilamide

A number of anthranilamide and 2-aminobenzenesulfonamide derivatives with aromatic aldehydes and 1,3-dicarbonyl compounds were synthesized. Substituted benzaldehyde derivatives of neither aminoamides showed tautomerism in solutions. Reaction products of 2-aminobenzenesulfonamide with p-substituted benzoylacetic aldehydes and p-substituted benzoylacetones undergo ring-chain tautomerism with a good linear correlation between the ring-chain equilibrium constants (log K, where K=[ring]/[chain]) and the Hammett-Brown σ⁺ parameters of the aromatic substituents. The equilibrium constant was measured for the reaction products of 2-aminobenzenesulfonamide with unsubstituted benzoylacetaldehyde at several temperatures which enabled the enthalpy and entropy of this reaction to be evaluated.     

金属载体强相互作用增强Au/TiO2催化剂在3-硝基苯乙烯选择性加氢反应的活性

自Haruta与Hutchings于上世纪八十年代末发现金纳米催化剂优异的反应活性以来,科研人员对金催化的应用领域进行了广泛而深入地研究.对金催化科学和应用领域的研究一直在进行.大量的研究表明,金催化剂在各种选择性氧化反应中具有优异的催化性能(高活性和高选择性).然而,在催化加氢反应中,尽管金催化剂相比于铂族金属显示出优越的选择性,但是由于金催化剂选择性加氢反应的活性较差,使其在选择性催化加氢反应中的应用受到了极大的限制.研究表明,金催化剂较弱的活化氢气能力是其催化加氢反应活性低的主要原因.研究发现,氢气活化的活性中心可能是界面、负价金、低配位的金原子等.金催化剂具有明显的载体效应,金属-载体之间的相互作用能够显著地改变金催化剂的催化性能.Tauster等研究发现,铂族金属与还原性载体之间存在强相互作用,能够引发载体包覆金属表面,并且使得电子从载体向金属迁移,导致金属带负电.受金属-载体强相互作用(SMSI)效应的启发,本文探究了Au/TiO2催化剂中SMSI对金催化剂加氢性能的影响.在H2或O2气氛下高温焙烧Au/TiO2,获得一系列金催化剂(Au/TiO2-TA,T为焙烧温度(oC):300、400、500和600;A为气氛:H2或O2).对比在3-硝基苯乙烯(3-NS)选择性加氢反应中的活性发现,Au/TiO2-500H的TOF值是Au/TiO2-500O的3.3倍;动力学测试表明,Au/TiO2-500H和Au/TiO2-500O的反应表观活化能分别为79.5和105.1 kJ/mol.这表明两类催化剂催化活性中心的结构存在差异.X射线光电子能谱测试结果表明,Au/TiO2-H样品中Au带部分负电,而Au/TiO2-O中Au显示为金属态.HAADF-STEM和EELS显示,Au/TiO2-H中Au NPs的表面有TiOx物种,增加了Au-TiO2的界面.EPR结果表明,Au/TiO2-H中存在表面Ti3+物种,而Au/TiO2-O样品中则没有.为确认加氢反应的活性中心到底是界面还是负价金物种,本文探究了不同温度下氢气处理的Au/TiO2的结构与性能的关系,发现Au/TiO2-300H/400H/500H催化剂都显示出较好的催化3-NS加氢活性,而Au/TiO2-600H虽然具有更多的负价金物种,但是3-NS选择性加氢反应的活性反而降低,因此,负价金不是活性中心.这是因为不同温度处理的Au/TiO2-H样品中,SMSI的强弱不同,在300、400、500 oC下,SMSI能够增加Au-TiO2的界面长度,从而增强了3-NS加氢反应的活性;而温度达到600 oC,SMSI效应太强,Au NPs被包覆更密实,导致Au/TiO2-600H的3-NS选择性加氢反应的活性下降.密度泛函理论计算表明,Au/TiO2-H样品具有更低的H2解离活化能以及氢转移活化能.氢氘交换反应也进一步验证了SMSI有利于H2的活化.