Synthesis of 2-selenoxo DHPMs by Biginelli reaction with Hf(OTf)4 as catalyst

By using Hf(OTf)₄ as catalyst, a series of 2-selenoxo DHPMs have been synthesized efficiently in good yields by Biginelli reaction with selenourea as starting material.     

Expeditious,Nano-BF3 · SiO2-Catalyzed Michaelis–Arbuzov Reaction in an Ionic Liquid: Synthesis of Privileged Aryl/Heterocyclic Phosphonates

An expeditious, simple, and green method was developed for the synthesis of privileged aryl/heterocyclicphosphonates, 8(a–c) to 13(a–c) through Michaelis–Arbuzov reaction of aryl/heterocyclic halides (Br), 1–6, and trialkylphosphites, 7(a–c), in room-temperature ionic liquid [bbim]Br using heterogeneous Lewis catalyst, nano-silica-supported boron trifluoride (BF₃-SiO₂). The advantages of this protocol are simplicity, good yield of the products, less reaction time (20–38 min), mild reaction conditions, easy workup, and reusability of the catalyst and ionic liquid. It is demonstrated that nano-BF₃-SiO₂ is a recoverable and easy accessible catalyst for the formation of C(sp²)-P bond in an ionic liquid.     

Nano-Fe3O4–Supported,Hydrogensulfate Ionic Liquid–Catalyzed,One-Pot Synthesis of Polysubstituted Pyridines

Abstract

Anchoring 1-methyl-3-(triethoxysilylpropyl) imidazolium chloride onto silica-coated magnetic Fe₃O₄ particles afforded the corresponding supported ionic liquid. Exchanging the Cl^? anion by treating with H₂SO₄ gave Brønsted ionic liquid 1-methyl-3-(triethoxysilylpropyl) imidazolium hydrogensulfate. The synthesized catalyst was characterized by various techniques such as infrared, x-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and elemental analyses. The results indicated that the prepared catalyst had a nanostructure. The catalytic activity of the supported ionic liquid was examined in the synthesis of the polysubstituted pyridines by reaction of aromatic aldehydes with acetophenones and ammonium acetate in moderate to good yields under solvent-free conditions. The catalyst can be easily recovered by applying an external magnetic field and reused for at least seven runs without deterioration in catalytic activity.     

The Efficient Synthesis of 3,4-Dihydropyrimidin-2-(1H)-Ones and Their Sulfur Derivatives with H2SO4 Immobilized on Activated Charcoal

Abstract

Various 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their sulfur derivatives were efficiently synthesized by a one-pot cyclocondensation reaction of aromatic and aliphatic aldehydes, β-dicarbonyl compounds and urea (or thiourea) in the presence of sulfuric acid immobilized on activated charcoal (133% w/w). The reactions were carried out in refluxing n-hexane-acetonitrile (2.5:0.5 mL) within 5–150 min to give 3,4-dihydropyrimidinones (or thiones) in high to excellent yields (81–97%).     

H6P2W18O62·14H2O as an efficient catalyst for the green synthesis of α-aminophosphonates from α-amino acids

Abstract

A simple, efficient and eco-friendly protocol has been described for the synthesis of α-aminophosphonates via Kabachnik-Fields reaction, catalyzed by H₆P₂W₁₈O₆₂·14H₂O as a reusable catalyst. The reaction was realized by condensation of amino acids, various aromatic aldehydes and triethylphosphite under solvent-free conditions, the corresponding α-aminophosphonates were formed in good yields. All the new products were characterized by IR, ¹H, ¹³C and ³¹P-NMR analyses. This method offers advantages such as simplicity workup with the green aspects, good yields and short reaction times.     

Efficient nucleophilic substitution reactions of highly functionalized allyl halides in ionic liquid media

Nucleophilic substitution reactions of highly functionalized allyl halides with three anions, N₃⁻, AcO⁻, and PhSO₂⁻, in ionic liquid media were conducted. The ionic liquid, [Bmim][BF₄], was found to be superior to classical organic solvents to give higher yields and faster reaction rates. The resulting products belong to multifunctionalized trisubstituted α,β-unsaturated ketones, which are useful building blocks for organic synthesis.     

A Novel and Convenient Synthesis of Coenzyme Q1

Abstract

A convenient and efficient synthetic route to Coenzyme Q₁ (6) starting from 3,4,5‐trimethoxytoluene (1) is described. The key features of this synthesis include the Diels–Alder reaction of 2,3‐dimethoxy‐l,4‐benzoquinone (3) with cyclopentadiene and the introduction of a C₅ side chain to 4,5‐dimethoxy‐2‐methyltricyclo[6.2.1.0^2,7]undeca‐4,9‐diene‐3,6‐dione (4) under mild conditions, (6) was obtained in overall 60% yield.     

An efficient synthesis of 1-cyanoacetyl-5-halomethyl-4,5-dihydro-1H-pyrazoles in ionic liquid

The synthesis of eleven 1-cyanoacetyl-5-hydroxy-5-halomethyl-4,5-dihydro-1H-pyrazoles from the reaction of 4-alkoxy-3-alken-2-ones f(R ³C(O)C(R ²) = C(R ¹)OR, where R ³ = CF₃, CCl₃, CHCl₂, CO₂ Et; R ²/R ¹ = H/H, H/Me, H/Et, -(CH₂)₄-, Me/H, H/Pr, and R = Me, Et) with cyanoacetohydrazide is reported. The reaction was carried out in the ionic liquid ([bmim][BF₄]) and molecular solvents. The results showed that when the ionic liquid was used as reaction medium, the reaction time was drastically decreased and the yield was improved.     

Silica-Supported Ionic Liquid Si-[SbSipim][PF6]: An Efficient Catalyst for the Synthesis of 3,4-Dihydropyrimidine-2-(1H)-ones

Silica-supported sulfonic acid–functional ionic liquid (Si-[SbSipim][PF₆]) was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones via a one-pot, three-component Biginelli reaction. The catalyst could be easily separated and reused six times without noticeable reduction inactivity. The process was simple and proceeded in excellent yields.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

An Efficient One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2‐ones Catalyzed by Methanesulfonic Acid

Abstract

An efficient synthesis of 3,4‐dihydropyrimidin‐2‐ones (DHPMs) from the aldehydes, β‐ketoesters, and urea in ethanol using methanesulfonic acid (CH₃SO₃H) as the catalyst is described. Compared with the classical Biginelli reaction conditions, this method has the advantage of excellent yields and short reaction time.     

离子液体中6-(2,3-环氧丙氧基)-2(1H)-喹啉酮及其衍生物的合成

6-(3-氨基-2-羟基丙基)-2-(1H)-喹啉酮衍生物被发现具有新的正性肌力的活性. 设计合成了一系列新的氨丙醇类喹啉酮化合物. 首先研究了6-羟基-2-(1H)-喹啉酮环氧化物2在离子液体中的合成, 该反应后处理简便, 收率高, 对环境友好. 然后用合成得到的2-(1H)-喹啉酮环氧化合物在离子液体中与一系列具有生物活性的有机碱反应, 合成了氨丙醇类2-(1H)-喹啉酮化合物3. 然后由6-羟基-2-(1H)-喹啉酮出发, 在离子液体中, 进行了一锅法合成氨丙醇类2-(1H)-喹啉酮化合物的研究. 制得的2b, 3b～3f 6个新化合物用IR, ¹H NMR, MS和元素分析进行了结构表征.     

An unusual oxidation-dealkylation of 3,4-dihydropyrimidin-2(1H)-ones mediated by Co(NO3)2·6H2O/K2S2O8 in aqueous acetonitrile

4-Aryl-6-methyl-3,4-dihydropyrimidin-2(1H)-one (DHPM) scaffolds of Biginelli type were oxidized using Co(II)/S₂O₈²⁻ and the reaction afforded 6-unsubstituted pyrimidin-2(1H)-ones through an unprecedented dealkylation process. 4-Alkyl DHPMs under similar conditions afforded yet another unusual product, ethyl tetrahydropyrimidin-2,4(1H,3H)-dione-5-carboxylate.     

An efficient synthesis of 1-cyanoacetyl-5-halomethyl-4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrazoles in ionic liquid

The synthesis of eleven 1-cyanoacetyl-5-hydroxy-5-halomethyl-4,5-dihydro-1H-pyrazoles from the reaction of 4-alkoxy-3-alken-2-ones f(R ³C(O)C(R ²) = C(R ¹)OR, where R ³ = CF₃, CCl₃, CHCl₂, CO₂ Et; R ²/R ¹ = H/H, H/Me, H/Et, -(CH₂)₄-, Me/H, H/Pr, and R = Me, Et) with cyanoacetohydrazide is reported. The reaction was carried out in the ionic liquid ([bmim][BF₄]) and molecular solvents. The results showed that when the ionic liquid was used as reaction medium, the reaction time was drastically decreased and the yield was improved. Correspondence: Marcos A. P. Martins, Núcleo de Química de Heterociclos – NUQUIMHE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.     

离子液体[TEAPS]HSO_4催化“一锅法”合成2-取代-1H-菲并[9,10-d]咪唑

在室温离子液体3-(三乙胺基)丙磺酸硫酸氢盐([TEAPS]HSO4)的催化作用下,由菲醌、醋酸铵和芳香醛"一锅法"合成了一系列2-取代-1H-菲并[9,10-d]咪唑化合物.实验中考察了投料比、催化剂用量、溶剂、反应时间对反应的影响,确定了最优反应条件,给出了可能的反应机理.此外催化剂可以方便的回收,且循环使用四次其催化活性并没有显著降低.目标产物经过了1HNMR,13CNMR,IR和MS确证表征.条件温和,反应时间短,产率高,且对环境友好.     

Synthesis of novel coumarinyl-pyrido[2,3-d]pyrimidine-2,4-diones using task-specific magnetic ionic liquid, [AcMIm]FeCl4 as catalyst

Abstract

An acid-functionalized magnetic ionic liquid, 1-acyl-3-methylimidazolium tetrachloroferrate, [AcMIm]-FeCl₄ has been utilized for the synthesis of a series of novel highly functionalized coumarinyl-pyrido[2,3-d]pyrimidine-2,4-dione derivatives (3a-3l) by the reactions of various 3-chloro-3-(2-oxo-2H-chromen-3-yl)acrylaldehydes (1) with functionalized aryl, 6-aminouracils. The major significant of the present procedure is the use of task-specific acidic ionic liquid which act as catalyst as well as reaction medium and thus avoiding use of organic solvent and/or protic acid catalyst. The other major advantages of the protocol are (i) shorter reaction time (1?h), (ii) easy work up procedure, (iii) excellent yields of products (91-94%), and (iv) recyclability of catalyst. The compounds (3a-3l) were identified using FT-IR, ¹H NMR, and ¹³C NMR and mass spectroscopic studies.     

Facile one-pot synthesis of 2-arylbenzothiazoles catalyzed by H3PO4/TiO2-ZrO2 (1/1) under solvent-free conditions

A highly efficient and simple protocol for the preparation of 2-arylbenzothiazoles through condensation of 2-aminothiophenol and different aldehydes in the presence of H₃PO₄/TiO₂-ZrO₂(1/1)-cetyl pyridinium bromide (CPB) is described. The reaction proceeded under mild and solvent-free conditions to afford 2-arylbenzothiazole derivatives. In this method, the title compounds were obtained in good to excellent yields and short reaction times. The structures of synthesized products were identified by infrared, ¹H NMR, ¹³C NMR, and mass spectroscopy.     

含氰基基团的以C为中心的不对称阴离子离子液体的合成、表征及应用

首次通过不对称阴离子的钠盐/钾盐和不同的季胺化的咪唑,吡咯溴盐/氯盐进行离子交换,合成了一系列含氰基官能团的不对称阴离子功能化离子液体。通过红外、核磁共振、质谱和元素分析对离子液体的结构进行表征;通过TGA对离子液体的热稳定性进行测定,结果发现不对称功能化离子液体具有良好的热稳定性,其分解温度在219-319℃范围内。将功能化离子液体[Bmim][C(CN)2COCH3]作为弱配体应用于模型的Suzuki偶联反应,发现在反应中加入功能化离子液体[Bmim][C(CN)2COCH3]可以使反应收率提高10-15%。     

D,L‐α‐Tocopherol Synthesis Catalyzed by the Brønsted Acidic Ionic Liquids

Abstract

The synthesis of D,L‐α‐tocopherol from trimethylhydroquinone and isophytol using the Brønsted acidic SO₃H‐functionalized ionic liquids as catalysts was explored. The catalytic activities of the SO₃H‐functionalized ionic liquids were dependent on their anions. The yield of D,L‐α‐tocopherol also depended on the solvent, which was the reaction medium. A yield of 94.3% was obtained using the SO₃H‐functionalized ionic liquid with [BF₄ ^?] anion as catalyst in propylene carbonate/heptane. The reaction mixture exhibited good biphasic behaviors, so that the produced D,L‐α‐tocopherol could be separated by decantation. The SO₃H‐functionalized ionic liquids could be reused after the removal of water.     

A Convenient Synthesis of 2-Amino-1,3- selenazoles Using Ionic Liquid and Microwave Irradiation

Abstract

A simple and environmentally benign synthesis of 2-amino-1,3-selenazoles by microwave irradiation using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) ionic liquid (IL) is described. Acyl halides, phenacyl halides, and α-bromo-β-keto esters easily undergo condensation with selenourea in ([Bmim]BF₄) by microwave irradiation to afford the desired products of good purity in excellent yields. The ionic liquid can be easily recovered and reused at least 10 times without losing its activity. The duration of the reaction ranges from 4–6 min.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

Efficient Synthesis of Spiro[diindenopyridine-indoline]triones Catalyzed by PEG-OSO3H-H2O and [NMP]H2PO4

One-pot, three-component synthesis of spiro[diindenopyridine-indoline]triones has been reported via the reaction of 1,3-indandione, aromatic amines, and isatins with (PEG-OSO₃H) as an efficient, polymeric acid surfactant–based catalyst in water and also in presence of acidic ionic liquid [NMP]H₂PO₄, which acts both as a medium and catalyst under conventional heating and ultrasonic irradiation. The reactions were complete in short reaction times with excellent yield of products. Surfactant-based PEG-OSO₃H could be recycled and reused several times without any significant loss of activity. The compounds exhibit fluorescence in methanol with large Stokes shift.