溴化镁催化的1,2,3,4-四氢吡啶酮无溶剂合成研究

An efficient and environmentally friendly procedure for the one-pot synthesis of tetrahydropyrimidinones from aldehydes, β-diketones and urea/thiourea by using magnesium bromide as an inexpensive and easily available catalyst under solvent-free conditions was described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of good to excellent yields (74%-94%) and short reaction time (45-90 min). The structure of the Biginelli reaction product from β-diketone, salicylaldehyde and urea has been proposed to possess an oxygen-bridge by cyclization (intramolecular Michael-addition).     

Green Biginelli‐type Reaction: Solvent‐free Synthesis of 5‐unsubstituted 3,4‐dihydropyrimdin‐2(1H)‐ones

The Biginelli‐type compounds, 5‐unsubstituted 3,4‐dihydropyrimdin‐2(1H)‐ones were synthesized by a one‐pot three‐component condensation of aromatic aldehydes, aromatic ketones and urea in the presence of SnCl₄ · 5H₂O under solvent‐free conditions. The advantages of this method are short reaction time (4–10 min), excellent yields (74–97%), inexpensive catalyst and solvent‐free conditions. A plausible mechanism was proposed.     

One‐pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalysed by Cupric Acetate under Solvent‐free Conditions

A solvent‐free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones from aromatic aldehydes, β‐keto ester/acetyl acetone and urea catalysed by cupric acetate under thermal condition is reported as a simple and an efficient protocol. Compared with classical Biginelli reaction reported in 1893, this new method provides much improved modification in terms of yield and reaction time. The usage of milder catalyst, environmental friendly procedures and excellent yields within a very short time (5–15 min) are the advantages of the method in which the involvement of solvent‐free condition adds an edge to the method. Thus, the efficiency of the protocol enabled the rapid synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one derivatives in a short duration.     

A new biginelli reaction procedure using potassium hydrogen sulfate as the promoter for an efficient synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one

Simple and improved conditions have been found to carry out the Biginelli reaction for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one derivatives. This synthesis was performed using potassium hydrogen sulfate as the promoter in ethylene glycol solution. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (85–95%) and short reaction time (0.5–2 h).     

Facile one‐pot synthesis of a series of 7‐aryl‐8H‐benzo[h]indeno[1,2‐b]quinoline‐8‐one derivatives catalyzed by cellulose‐based magnetic nanocomposite

A sulfonated magnetic cellulose‐based nanocomposite was applied as an efficient, inexpensive and green catalyst for the one‐pot three‐component synthesis of 7‐aryl‐8H ‐benzo[h ]indeno[1,2‐b ]quinoline‐8‐ones starting from 1,3‐indanedione, aromatic aldehydes and 1‐naphthylamine under solvent‐free conditions in high yields (79–98%) within short reaction times (2–5 min). The nanobiostructure catalyst can be easily separated from the reaction mixture by using an external magnet and reused several times.     

Lewis Acid Catalyzed Synthesis of 1‐Aryl‐1,2‐dihydro‐naphtho[1,2‐e][1,3]oxazin‐3‐ones under Solvent Free Conditions: A Mechanistic Approach

Lewis acids catalyzed highly efficient one‐pot three component coupling of β‐naphthol, benzaldehydes and urea to produce 1‐aryl‐1,2‐dihydro‐naphtho[1,2‐e][1,3]oxazin‐3‐one derivatives under solvent free conditions is described. Mechanistic studies confirmed that product formation is possible only at very high temperature (140–150°C) and at lower temperature (90–100°C) formation of 14‐aryl‐14H‐dibenzo(a,j)xanthenes was observed. Among the nine Lewis acids screened, iodine, P₂O₅ and Yb(OTf)₃ are found to be most effective catalyst for this multicomponent reaction.     

Unexpected One‐pot Synthesis of Novel 2‐Aminopyrimidine‐4‐ones under Microwave Irradiation

One‐pot, three‐component condensation of guanidine, ethylbenzoylacetate and various aromatic aldehydes in the presence of NaHCO₃ have been investigated by microwave irradiation. The aromatic aldehydes bearing electron‐withdrawing groups undergo condensation with guanidine and ethylbenzoyl‐acetate to afford ethyl‐2‐amino‐4‐aryl‐1,4‐dihydro‐6‐phenylpyrimidine‐5‐carboxylate derivatives via Biginelli reaction. However, reaction of the aromatic aldehydes having electron‐releasing groups with guanidine and ethylbenzoylacetate did not give the corresponding dihydropyrimidines. Instead, novel 2‐amino‐5‐benzoyl‐5,6‐dihydro‐6‐arylpyrimidine‐4(3H)‐ones were obtained via an unexpected mechanism.     

Phosphotungstic acid grafted zeolite imidazolate framework as an effective heterogeneous nanocatalyst for the one‐pot solvent‐free synthesis of 3,4‐dihydropyrimidinones

Phosphotungstic acid (H₃PW₁₂O₄₀, PTA) supported on ZIF‐9(NH₂) was synthesized for the first time and performed as an effective and environmental friendly catalyst in the one‐pot three component Biginelli condensation of different substituted benzaldehydes with ethyl acetoacetate and urea to afford the corresponding 3,4‐dihydropyrimidin‐2‐(1H)‐ones under solvent‐free conditions. ZIF‐9(NH₂) and the prepared nanocatalyst PTA@ZIF‐9(NH₂) were characterized by XRD, FESEM, TEM, EDX, BET, AAS, TGA, UV–Vis, and FT‐IR. After reaction, the nanocatalyst can be easily separated from the reaction mixture by centrifuge and the recovered catalyst can be reused for at least five times with a 14% reduction in yield after the fifth run. This study showed that ZIF‐9(NH₂) can be utilized as a promising support for PTA and developed a highly active, stable and reusable heterogeneous catalyst under easy reaction condition in the multi‐component organic synthesis.     

Syntheses,spectral property,and antimicrobial activities of 6‐α‐amino dibenzo [d,f][1,3,2]dioxaphosphepin 6‐oxides

Diethyl α‐aminophosphonates ( 4 ) were prepared in excellent yield from three‐component reaction of aldehydes ( 1 ), amines ( 2 ), and triethylphosphite ( 3 ) under solvent‐free conditions in the presence of ceric ammonium nitrate (CAN) and were reacted with 2,2′‐dihydroxybiphenyl ( 5 ) using p‐toluene sulfonic acid monohydrate (PTSA) as a catalyst to obtain 6‐α‐aminodibenzo[d f][1,3,2]dioxaphosphepin 6‐oxides ( 6 ) in good yield. It is a first report on the cyclizations of 4 with 5 . An antimicrobial activity of numbers of 6 is evaluated. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:2–8, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20244     

Preparation and Structure of Magnesium Bis(hydrogen β‐glutamate) Hexahydrate

The dissociation equilibria of aqueous solutions of β‐glutamic acid were studied by potentiometric titration and the three pK values determined under standard conditions. The hydrogen β‐glutamate anion β‐GluH⁻ was found to be the dominating species in the physiologically relevant pH range 4.0–9.4. Neutralization of β‐glutamic acid by magnesium oxide affords magnesium bis(hydrogen β‐glutamate) Mg (β‐GluH)₂, which crystallizes as the hexahydrate from dilute aqueous solution. A single‐crystal X‐ray study showed that the β‐GluH⁻ anions are not part of the coordination sphere of the magnesium ion. Instead hexahydrated dications [Mg(H₂O)₆]²⁺ are intimately associated with free β‐GluH⁻ anions through a three‐dimensional network of H‐bonds. This study provides the first structural and conformational reference data for the β‐GluH⁻ anion.     

Stereoselective synthesis of new dihydropyrimidinone glycoconjugates #

Stereoselective synthesis of dihydropyrimidinone glycoconjugates in high yields, from different sugar aldehydes, by a three‐component coupling (Biginelli) reaction is reported. In this new method, HC1 generated ‘in situ’ from2,4,6‐trichloro[l,3,5]triazine(TCT; 10 mol%), was used under mild and solvent free reaction conditions.     

β‐Diketiminate Stabilized Magnesium Hydroxide,Heterobimetallic, and Halide Complexes: Synthesis and X‐ray Structural Studies

The controlled hydrolysis of heteroleptic magnesium amide, LMgN(SiMe₃)₂ (L = CH[C(Me)N(2,6‐iPr₂C₆H₃)]₂) with water afforded the corresponding hydroxide [LMg(OH)·THF]₂ as air and moisture sensitive compound. The presence of a sterically bulky β‐diketiminate ligand prevents the self‐condensation reaction of this hydroxide complex. Single crystal X‐ray analysis shows that the hydroxide is dimeric in the solid state. Reaction of the magnesium amide or LMg(Me)·OEt₂ with LAlMe(OH) generates the heterobimetallic species containing the Mg–O–Al moiety. Additionally, the reaction of methylmagnesiumchloride with the free ligand leads to complex L′MgCl (L′ = CH[Et₂NCH₂CH₂N(CMe)]₂). As revealed by the crystal structure, L′MgCl is a solvent free monomeric magnesium chloride complex that is analogues to the Grignard reagent.     

Rapid Synthesis of 1,2,3,4-Tetrahydropyrimidin-2-ones Using Zn（NH2SO3）2 as a Catalyst under Microwave Irradiation

Rapid synthesis of 1,2,3,4-tetrahydropyrimidin-2-ones （THPO） from aromatic aldehydes, β-ketoester and urea （or thiourea） using zinc sulfamate as the catalyst under microwave irradiation was described here. Compared with the classical Biginelli reaction, this new method consistently has the advantages of good yields （76%-96%）, short reaction time （3-15 min）, no corrosion to equipments, ease of manipulation, and low cost catalyst.     

Gallium(III) Iodide‐catalyzed Biginelli‐type Reaction Under Solvent‐free Conditions: Efficient Synthesis of Dihydropyrimidine‐2(1H)‐one Derivatives

The Biginelli‐type condensation of ethyl acetoacetate/cycloketone, aldehyde and urea/thiourea under solvent‐free condition catalyzed by 10% gallium(III) iodide to form dihydropyrimidine‐2(1H)‐one derivatives was described. This process offered one way to constructing dihydropyrimidine‐2(1H)‐ones in good to excellent yields with simple procedure and short reaction time.     

An efficient and green method for the synthesis of N‐phosphoramino o‐hydroxylphenyl α‐aminophosphonic monoesters

An efficient and green method to the synthesis of N‐protected o‐hydroxylphenyl α‐amino‐alkylphosphonic monoesters is described. It consists of the three‐component Mannich‐type reaction of phosphoramides, carbonyl compounds (aldehydes or ketones), and 2‐chlorobenzo[1,3,2] diox‐aphospholes under solvent‐free and catalyst‐free conditions, followed by hydrolysis. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:596–601, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20483     

Piperazine‐functionalized nickel ferrite nanoparticles as efficient and reusable catalysts for the solvent‐free synthesis of 2‐amino‐4H‐chromenes

Piperazine‐functionalized nickel ferrite (NiFe₂O₄) nanoparticles were synthesized as recoverable heterogeneous base catalysts using a routine method. The synthesized materials were characterized using various spectroscopic techniques such as infrared, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, thermogravimetry analysis, and vibrating sample magnetometry. Catalytic efficiency was investigated in the synthesis of 2‐amino‐4H‐chromene derivatives via a one‐pot three component reaction of aldehyde and malononitrile with β or α‐naphthol/5‐methyle resorcinol under solvent‐free conditions with good to high yields. This method is operationally simple and has several advantages such as good to high yield, short reaction times, solvent‐free conditions, and easy synthesis. Moreover, the catalyst was recovered easily using an external magnet and reused three times without distinctive loss in catalytic activity.     

A Catalyst‐Free Aqueous Synthesis of 2‐Amino‐7,9‐dihydrothieno[3′,2′:5,6]pyrido[2,3‐d]pyrimidine‐4,6(3H,5H)‐dione Derivatives

A series of novel 7,9‐dihydrothieno[3′,2′:5,6]pyrido[2,3‐d]pyrimidine‐4,6(3H,5H)‐dione derivatives were synthesized efficiently via the catalyst‐free reaction of aldehyde, ethyl 2,4‐dioxotetrahydrothiophene‐3‐carboxylate, and 2,6‐diaminopyrimidine‐4(3H)‐one through the sequence of deethoxycarbonylation and three‐component condensation in aqueous media. This protocol featured mild reaction conditions, high yields, easy work‐up, and environmentally friendly procedure.     

An Efficient One‐Pot Synthesis of 7,7‐Dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one Derivatives Using Chitosan–SO3H as Biodegradable Organocatalyst

Chitosan sulfonic acid (CS–SO₃H), a biodegradable green catalyst, was found to be an impressive system for one‐pot four‐component reaction of different aromatic aldehydes, 3‐acetylcoumarin, dimedone, and ammonium acetate leading to 7,7‐dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one under solvent‐free condition. This methodology produces diverse superiorities such as operational simplicity, short reaction time, and high yield. Further, the catalyst can be reused for four times without any noticeable decrease in the catalytic activity.     

Synthesis,Structure, and Some Transformations of Novel 1,5‐methanonaphtho[1,2‐g][1,3,5]oxadiazocine Derivatives

Biginelli reaction of thiourea, 2‐hydroxy‐1‐naphthaldehyde, and acetoacetic ester (or benzoyl acetone) under solvent‐free conditions and MW irradiation gave novel 3‐thioxo‐2,3,4,5‐tetrahydro‐1H‐1,5‐methanonaphtho[1,2‐g][1,3,5]oxadiazocine derivatives. Subsequent reaction of the obtained compounds with α‐chloroacetamide led to 5‐methyl‐5H,13H‐5,13‐methanonaphtho[1,2‐g] thiazolo[2,3‐d][1,3,5]oxadiazocin‐1(2H)‐ones, which were converted to the Z‐isomers of 2‐arylylidene‐5H,13H‐5,13‐methanonaphtho[1,2‐g]thiazolo[2,3‐d][1,3,5]oxadiazocin‐1(2H)‐one derivatives by reaction with arylaldehydes. The structures of the products were characterized by 1H NMR, 13C NMR spectra, and X‐ray analysis.     

Cobalt‐based metal coordination polymers with 4,4′‐bipyridinyl groups: highly efficient catalysis for one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions

Three new metal coordination complexes, namely [Co(BPY)₂(H₂O)₂](BPY)(BS)₂(H₂O)₄ ( 1 ), [Co(BPY)₂(H₂O)₄](ABS)₂(H₂O)₂ ( 2 ) and [Co(BPY)(H₂O)₄](MBS)₂ ( 3 ) (BPY = 4,4′‐bipyridine, BS = phenylsulfonic acid, ABS = p‐aminobenzenesulfonic acid, MBS = p‐methylbenzenesulfonic acid), were obtained under hydrothermal conditions. Complexes 1 , 2 , 3 were structurally characterized using single‐crystal X‐ray diffraction and infrared spectroscopy. All of them display low‐dimensional motifs: complex 1 displays a two‐dimensional structure; and complexes 2 and 3 exhibit a one‐dimensional tape structure. Through strong intermolecular hydrogen bonding interactions and weak packing interactions, all of them further stack to generate a three‐dimensional supramolecular architecture. Catalysts 1 , 2 , 3 were involved in the green synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions through Biginelli reactions. The corresponding catalytic product was obtained in quantitative yields (99%) under eco‐friendly synthesis conditions for the variety of reactions. Catalysts 1 , 2 , 3 exhibit excellent efficiency for the desired product, and their catalytic performance shows the following order: 2  >  1  ≈  3 , which can be ascribed to the hydrophobic interactions of different phenylsulfonate groups. The catalytic performance for the Biginelli reaction is not only dependent on the selected solvents, but also inversely proportional to the polarities of the solvents. Copyright © 2016 John Wiley & Sons, Ltd.