Efficient one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones from aromatic aldehydes and their one-pot oxidation to quinazolin-4(3H)-ones catalyzed by Bi(NO3)3·5H2O: Investigating the role of the catalyst

An efficient and novel synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones via one-pot, three-component reaction of isatoic anhydride, primary amines and aromatic aldehydes catalyzed by Bi(NO₃)₃·5H₂O under solvent-free conditions is described. Oxidation of these 2,3-dihydroquinazolin-4(1H)-ones to their quinazolin-4(3H)-ones was also successfully performed in the presence of Bi(NO₃)₃·5H₂O. This new method has the advantages of convenient manipulation, short reaction times, excellent yields, very easy work-up, and the use of commercially available, low cost and relatively non-toxic catalyst. The role of Bi(NO₃)₃·5H₂O was also investigated in these transformations.     

Microwave-induced bismuth(III)-catalyzed synthesis of linear indoloquinolines

Microwave-induced Bi(NO₃)₃-catalyzed one-pot synthesis of a series of linear indoloquinolines is accomplished under mild reaction conditions. While majority of these examples were carried out under solvent-free conditions, in a few cases, minimal quantity of THF is used as solvent. The methodology involves several unique reaction pathways, providing different linear indolo[2,3-b]quinolines in good yields from readily available starting materials and using environmentally benign Bi(NO₃)₃·5H₂O as catalyst.     

M(HSO4)n-Promoted Synthesis of 2-Aryl-1-arylmethyl-1H-1,3-benzimidazole Derivatives

We have developed a highly selective synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles from the reaction of o-phenylenediamines and aromatic aldehydes in the presence of metal hydrogen sulfates [M(HSO₄)_n] in water and also under solvent-free conditions in good to excellent yields.     

Fe(HSO4)3 Promoted Trimethylsilylation of Alcohols and Phenols in Solution and Under Solvent-Free Conditions

Summary. Alcohols and phenols are efficiently converted to their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of Fe(HSO₄)₃ in solution and under solvent-free conditions.     

Synthesis,structure, and properties of organoplatinum(ii) derivatives of diphenyl ether

New mono- and disubstituted organoplatinum(II) derivatives of diphenyl ether,cis-(PhOC₆H₄-o)PtCl(PPh₃)₂ and (o-C₆H₄OC₆H₄-o)Pt(PPh₃)₂, were synthesized by the reaction of 2,2-dilithium diphenyl oxide withcis-Cl₂Pt(PPh₃)₂. Transmetallation of (PhOC₆H₄-o)AuPPh₃ withcis-Cl₂Pt(PPh₃)₂ was studied using³¹P NMR monitoring. This reaction proceeds with the retention of configuration to afford ClAuPPh₃ andcis-(PhOC₆H₄-o)PtCl(PPh₃)₂ under kinetically controlled conditions. The latter complex irreversibly isomerizes into thetrans isomer in the presence of equimolar quantities of ClAuPPh₃, whereas, in the presence of free PPh₃, this isomerization is reversible. The structures of the obtained diphenyl oxide derivatives of platinum were confirmed by³¹P NMR and FAB mass spectrometry. It was established by X-ray structural analysis that in thecis-(PhOC₆H₄-o)PtCl(PPh₃)₂ complex, the Pt atom is in a nearly square-planar coordination, and secondary intramolecular Pt...O interaction occurs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1814–1820, October, 1994.We would like to thank A. L. Blyumenfel'd and P. V. Petrovskii for recording the 31p NMR spectra, and D. V. Zagorevskii and K. V. Kazakov for measuring the mass spectrometric characteristics.This work was supported by the International Science Foundation (Project No. MDV 000).     

KAl(SO4)2 · 12H2O (alum) a reusable catalyst for the synthesis of some 4-substituted coumarins via Pechmann reaction under solvent-free conditions

A simple, efficient, and practical procedure for the Pechmann condensation using KAl(SO₄)₂ · 12H₂O (alum) as a non-toxic, reusable, inexpensive, and easily available catalyst is described under solvent-free condition at 65°C. These improved reaction conditions allow the preparation of a wide variety of some new substituted coumarins in high yields (86–96%) and purity under mild reaction conditions. Compared to the classical Pechmann condensation, this new method consistently has the advantage of high yields. Correspondence: Ali A. Mohammadi, Department of Chemistry, Shahid Beheshti University, P.O. Box 19839-4716, Tehran, Iran.     

Alum (KAl(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 12H<Subscript>2</Subscript>O) Catalyzed One-Pot Synthesis of Coumarins under Solvent-Free Conditions

Summary. Alum (KAl(SO₄)₂ · 12H₂O) is used as an efficient catalyst in the Pechmann condensation of phenol derivatives with β-keto esters leading to the formation of coumarins in excellent yields under solvent-free conditions. This methodology offers significant improvements for the synthesis of coumarins with regard to the yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents.     

RuCl3·xH2O: A Novel and Efficient Catalyst for the Facile Synthesis of 1,5-Benzodiazepines Under Solvent-Free Conditions

1,5-Benzodizepines are synthesized in excellent yields via condensation of o-phenylenediamine with ketones having a hydrogen at the α-position. The reaction is performed in solvent-free conditions and 5 mol% of RuCl₃·xH₂O is enough to direct the reaction to completion.     

Synthesis of 3-aryl-4(3H)-quinazolinones from anthranilic acid, ortho esters, and anilines using Ce(CH3SO3)3·2H2O as catalyst

Abstract  

3-Aryl-4(3H)-quinazolinones were synthesized efficiently by the three component one-pot cyclocondensation of anthranilic acid, ortho esters, and anilines in the presence of Ce(CH₃SO₃)₃·2H₂O at room temperature under solvent-free conditions. This method offers several advantages, such as a simple procedure, mild reaction conditions, short reaction time, and reusability of the catalyst.     

Modified Glaser Reaction of Terminal Alkynes on KF/Alumina

Summary. A variety of 1,3-diyne compounds are prepared in a solvent-free reaction on KF/alumina in the presence of catalytic amounts of Cu(OAc)₂·H₂O with up to 96% yields at room temperature.     

无溶剂一锅法Al(ClO4)3催化合成α-氨基膦酸酯

以无水高氯酸铝为催化剂, 将芳香醛、芳香胺及亚磷酸酯在无溶剂条件下一锅法反应, 高效地合成了α-氨基膦酸酯, 该催化剂优于其它已发现的催化剂[如Mg(ClO₄)₂, BiCl₃, AlCl₃等], 建立了一种适用于含有钝化基团的芳香胺的α-氨基膦酸酯的新合成方法.     

Bi(NO3)3.5H2O catalyzed phosphonylation of aldehydes: An efficient route to α-hydroxyphosphonates

The Bi(NO₃)₃.5H₂O mediated synthesis of α-hydroxyphosphonates via phosphonylation of aldehydes is reported herein. Both conventional and microwave technology was efficiently applied to range of aromatic, heteroaromatic, α,β-unsaturated aldehydes under solvent-free conditions. The solvent free conditions, avoidance of toxic reagents and excellent yield are some of the remarkable features of this protocol to access the medicinally privileged structure, α-hydroxyphosphonates.     

Simple and efficient synthesis of 3-aminopropenones and 3-aminopropenoates catalyzed by copper(II) nitrate trihydrate under solvent-free conditions

A simple, efficient and environmentally begin method has been developed for the synthesis of 3-aminopropenones and 3-aminopropenoates through the reaction of 1,3-dicarbonyl compounds with amines in the presence of Cu(NO₃)₂ · 3H₂O under solvent-free conditions. Correspondence: Geng-Chen Li, School of Material Science and Engineering, Shijiazhuang Railway Institute, Shijiazhuang 050043, China.     

1,3-Dibromo-5,5-dimethylhydantoin as an efficient homogeneous catalyst for synthesis of benzoxazoles, benzimidazoles, and oxazolo[4,5-b]pyridines

Abstract  

A simple and highly efficient method for synthesis of benzoxazoles, benzimidazoles, and oxazolo[4,5-b]pyridines is described. Condensation of orthoesters with o-substituted anilines or 2-amino-3-hydroxypyridine was performed in the presence of catalytic amounts of commercially available, inexpensive, and moisture-stable 1,3-dibromo-5,5-dimethylhydantoin under solvent-free conditions. The corresponding heterocycles were obtained in good to excellent yields. The main advantages of the present procedure are mild reaction conditions, short reaction times, high yields of products, easy work-up, and absence of solvent.     

无溶剂中性条件下分子I2或Fe(NO3)3·9H2O/NaI原位生成的I2催化醇与甲酸甲酰化反应

 Different alcohols were formylated by formic acid under solvent-free conditions in the presence of iodine as the catalyst with good-to-high yields at room temperature. I₂ generated in situ from Fe(NO₃)₃·9H₂O/NaI also catalyzed the formylation of the alcohols under solvent-free conditions. This gives a green and efficient reaction at room temperature, in which the use of toxic and corrosive molecular I₂ is avoided.     

Synthesis,Characterization, and Antimicrobial Evaluation of Sulfonamides Containing N-Acyl Moieties Catalyzed by Bismuth(III) Salts Under Both Solvent and Solvent-Free Conditions

Efficient N-acylation of sulfonamides with both readily available carboxylic acid chlorides and anhydrides has been carried out with catalysis by bismuth(III) salts including BiCl₃ and Bi (OTf)₃. The reactions proceed rapidly in both heterogeneous and solvent-free conditions and afforded the corresponding N-acylsulfonamides in good to excellent yields. The mild reaction conditions and low toxicity of bismuth salts make this procedure attractive and in close agreement with the goals of green chemistry. Some of the synthesized compounds were evaluated in vitro as antimicrobial agents against representative strains of Gram-positive (Staphylococcus aureus ATCC 25922, clinical strains of Staphylococcus aureus VISA and Enterococcus spp.) and Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, clinical strains of Klebsiella pneumonia and Escherichia coli) and as antifungal agents against Candida albicans (clinically isolated) by both disc diffusion and minimal inhibition concentration (MIC) methods. All these bacteria and fungi studied were screened against some antibiotics to compare with our chemicals' zone diameters.     

Organoaluminum Compounds as Catalysts for Monohydroboration of Carbodiimides

The effective catalytic activity of organoaluminum compounds for the monohydroboration of carbodiimides has been demonstrated. Two aluminum complexes, 2 and 3 , were synthesized and characterized. The efficient catalytic performances of four aluminum hydride complexes L¹AlH₂ (L¹=HC(CMeNAr)₂, Ar=2,6-Et₂C₆H₃; 1 ), L²AlH₂(NMe₃) (L²=o-C₆H₄F(CH=N-Ar), Ar=2,6-Et₂C₆H₃; 2 ), L³AlH (L³=2,6-bis(1-methylethyl)-N-(2-pyridinylmethylene)phenylamine; 3 ), and L⁴AlH(NMe₃) (L⁴=o-C₆H₄(N-Dipp)(CH=N-Dipp), Dipp=2,6-iPr₂C₆H₃; 4 ), and an aluminum alkyl complex L¹AlMe₂ ( 5 ) were used for the monohydroboration of carbodiimides investigated under solvent-free and mild conditions. Compounds 1 – 3 and 5 can produce monohydroborated N-borylformamidine, whereas 4 can afford the C-borylformamidine product. A suggested mechanism of this reaction was explored, and the aluminum formamidinate compound 6 was characterized by single-crystal X-ray, also a stoichiometric reaction was investigated.     

Zinc perchlorate catalyzed one-pot synthesis of 3,4-dihydropyrimidinones under solvent-free conditions

Abstract

In this paper, we report zinc perchlorate hexahydrate [Zn(ClO₄)₂?6H₂O] as a highly effective catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. These improved reaction conditions allow the preparation of a wide variety of substituted dihydropyrimidinones in high yields and purity under mild reaction conditions. Compared with the classical Biginelli reaction, this method has the advantage of excellent yields and short reaction time in solvent-free conditions.     

SbCl3-catalyzed solvent-free Friedel–Crafts reaction of phenols with mandelic acids to 3-aryl benzofuran-2(3H)-ones: Synthesis of spirocyclic 2,3-dihydrobenzofuran-2-ones

A facile, SbCl₃-catalyzed, one-pot, tandem Friedel–Crafts/lactonization reaction of phenols and mandelic acids has been developed under solvent-free conditions to afford 3-aryl benzofuran-2(3H)-ones in good to high yields (52–90%). Additionally, the utility of 3-aryl benzofuran-2(3H)-ones is demonstrated by using them as precursors in the synthesis of a new class of spirocyclic benzofuran-2-ones using classical synthetic methodologies.