Silica-supported tungstic acid (STA): A recyclable catalyst for the synthesis of 1H-indazolo [1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives under solvent-free condition

Abstract

An efficient one-pot synthesis of 1?H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives via three-component condensation reaction of phthalhydrazide or 4-phenylurazole, aldehydes or isatins and dimedone in the presence of a catalytic amount of silica-supported tungstic acid (STA), as a heterogeneous solid acid catalyst under solvent-free conditions is presented. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yields, short reaction time, simple workup, recovery and reusability of catalyst with broad scope of usable substrates. This has made the protocol sustainable and economic.     

Water mediated synthesis of various [1,3]oxazine compounds using alum as a catalyst

Abstract

A simple, efficient, and practical procedure for the synthesis of various substituted 2,3-dihydro-2-phenyl-1H-naphtho[1,2-e][1,3]oxazines and 3,4-dihydro-3-phenyl-2H-naphtho[2,1-e][1,3]oxazines using KAl(SO₄)₂ 12H₂O (alum) as a non-toxic, reusable, inexpensive, and easily available catalyst is described using water as a solvent. These improved reaction conditions allow the preparation of a wide variety of substituted [1,3]oxazines in high yields and purity under mild reaction conditions.     

Asymmetric Direct Aldol Reactions Catalyzed by a Simple Chiral Primary Diamine–Br⊘nsted Acid Catalyst in/on Water

Abstract

The direct asymmetric aldol reaction catalyzed by the simple and commercially available chiral primary diamines, (1S,2S)-1,2-diphenylethane-1,2-diamine and (1R,2R)-1,2-diphenylethane-1,2-diamine, is presented. The catalyst system is a primary amine with Br?nsted acid–catalyzed direct aldol reaction of p-nitrobenzaldehyde and cyclohexanone with high chemo- and stereoselectivity on water, which furnishes the corresponding β-hydroxyketone with up to 94% ee.     

Multi-component reaction synthesis of novel 3-phenyl-3,4-dihydro-2H-benzo[a][1,3] oxazino[5,6-c]phenazine derivatives catalyzed by reusable ZnO-PTA@Fe3O4/EN-MIL-101(Cr) nanopowder at room temperature

ABSTRACT

A simple, one-pot procedure for the synthesis of novel 3-phenyl-3,4-dihydro-2H-benzo[a][1,3] oxazino[5,6-c]phenazine derivatives by four-component coupling reaction between benzo[a]phenazine-5-ol, formaldehyde and amine in the presence of a catalytic amount ZnO-PTA@Fe₃O₄/EN-MIL-101(Cr) nanopowder in ethanol at room temperature under stirring condition. ZnO-PTA@Fe₃O₄/EN-MIL-101(Cr) An inorganic magnetic catalyst was analyzes and described by the XRD, TEM, FESEM, TGA, AFM, VSM and ICP-OES. This study presents simple, efficient, and one-pot multicomponent protocol, which provides several advantages such as short reaction times, high yields, easy working up, chromatography-free technique, catalyst recovery, and reusability are other highlights of this work.     

One‐pot and green synthesis 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and dihydropyrano[3,2-c]chromene derivatives by Fe3O4@SiO2-imine/phenoxy-Cu(II) as an efficient and reusable catalyst

In the current study, magnetite-silica core–shell nanoparticles modified with Cu-salen complex (Fe₃O₄@SiO₂-imine/phenoxy-Cu(II)) was utilized as a heterogeneous catalyst for the one-pot multicomponent synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and dihydropyrano[3,2-c]chromene derivatives under solvent-free conditions, without using any harmful organic reagents/solvent. The current synthetic protocol demonstrates that the reactions proceeds to completing step, leading to the successful synthesis of high purity compounds. Advantages of this method include easy purification, reusability of the catalyst, green and mild procedure and synthesis of new derivatives in high yields within short reaction time.

     

Amelioration of H4[W12SiO40] by nanomagnetic heterogenization: For the synthesis of 1H–pyrazolo[1,2‐b]phthalazinedione derivatives

We conveniently coated silicotungstic acid (STA, H₄[W₁₂SiO₄₀]) on amino‐functionalized Si–magnetite nanoparticles, as surface functionalization of magnetic nanoparticles is an excellent way for green and efficient catalysis. The nanoparticles were structurally characterized using various techniques. The catalytic activity and recyclability of the STA–amine–Si–magnetite nanoparticles were probed through synthesis of 1H–pyrazolo[1,2‐b]phthalazinedione derivatives. The reaction proceeds smoothly to provide products in excellent yields and short reaction times. The catalyst could be readily recovered using a simple external magnet and reused several times without any significant loss in activity. Herein, we report a comparison of the activity of H₄[W₁₂SiO₄₀] as a homogeneous and heterogeneous catalyst, the latter being found to be more efficient. The findings offer effective methods for environmentally friendly synthesis of pyrazolo[1,2‐b]phthalazinedione derivatives.     

One-Pot Synthesis of Benzo[4,5]imidazo[1,2-a]pyrimidin-2-ones Using a Hybrid Catalyst Supported on Magnetic Nanoparticles in Green Solvents

The conversion of soluble polyoxometalate into insoluble polyoxometalate is considered to be one of the major challenges in synthetic organic chemistry. Here, polyoxometalate was bonded to the salt part of an organic branch immobilized on the silica-coated Fe₃O₄ nanoparticle and characterized using various techniques. The fabricated complex was used as a heterogeneous catalyst in a novel one-pot reaction for synthesis of benzo[4,5]imidazo[1,2-a]pyrimidin-2-ones using aromatic amines, dimethyl acetylenedicarboxylate (DMAD), derivatives of benzaldehyde and 2-aminobenzimidazole in water/ethanol as a green solvent. 21 derivatives of benzo[4,5]imidazo[1,2-a]pyrimidin-2-one were synthesized by this method and fully characterized. The high stability of the catalyst showed that it can be reused for 6 times without decreasing in activity. The combination of new synthetic method, new ferromagnetic heterogeneous nano-catalyst, green solvent and simple separation method were presented in this work.     

Synthesis and Glycosidic Reaction of 1,2-Anhydromanno-, Lyxo-, Gluco-, and Xylofuranose Perbenzyl Ethers

ABSTRACT

Stereospecific synthesis of 1,2-anhydromanno-, lyxo-, gluco-, and xylofuranose perbenzyl ethers was successfully achieved via intramolecular S _N2 reaction of the corresponding C-1 alkoxide with C-2 bearing tosyloxy group. The key intermediates, furanose 2-sulfonates, were prepared from the corresponding 1,2-diols and tosyl chloride under phase transfer conditions in good yields. Condensation of the anhydro sugars with 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose or N-benzyloxycarbonyl L-serine methyl ester in the absence of catalyst gave 1,2-trans-linked glycofuranosides in high yield.     

Cu-catalyzed one-pot multicomponent approach for the synthesis of symmetric and asymmetric 1,4-dihydropyridine (1,4-DHP) linked 1,2,3-triazole derivatives

Abstract

Synthesis of various symmetric and asymmetric 1,4-DHP linked 1,2,3-triazole derivatives from economical and readily available starting materials via a convenient methodology in a single-pot method using CuSO₄·5H₂O as an efficient catalyst has been reported. The reaction proceeded efficiently under the optimized reaction conditions with excellent functional group compatibility providing the desired products in good yields. The method appears to be an efficient combinatorial strategy for the synthesis of new 1,4-DHP linked triazole derivatives.     

Deep eutectic solvent-mediated expedient multicomponent synthesis of oxazine scaffolds

A simple, efficient, and eco-friendly protocol for the synthesis of 1,3-oxazine derivatives, viz. 7-aryl-7,8-dihydro-6H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-e][1,3]oxazines and 3-aryl-3,4-dihydro-2H- naphtho[2,3-e][1,3]oxazine-5,10-diones, involving one-pot multicomponent condensation reaction of various amines and formaldehyde with sesamol/2-hydroxy-1,4-naphthoquinone, respectively, catalyzed by a choline chloride–oxalic acid deep eutectic solvent has been developed. The method offers several advantages, including mild reaction conditions, simple operating procedure, recyclable and biodegradable catalyst, short reaction times, and excellent yields of the target products.

     

Lithium bromide as an efficient,green, and inexpensive catalyst for the synthesis of quinoxaline derivatives at room temperature

Abstract

An efficient, simple, and green procedure for the synthesis of quinoxaline derivatives is described. The condensation of 1,2-diamines with 1,2-diketones using lithium bromide (LiBr) in H₂O/EtOH as a green reaction media at room temperature affords the title compounds in high to excellent yields and in short reaction times.     

An efficient one-pot synthesis of anthraquinone derivatives catalyzed by alum in aqueous media

Abstract

Alum (KAl(SO₄)₂·12H₂O) performs as a novel catalyst for the synthesis of anthraquinone derivatives from phthalic anhydride and substituted benzenes in good to excellent yields (70–96%) using water as a solvent at ambient temperature. Several solvents were examined for this reaction; however, in terms of reaction yield and time, water was found to be the optimum solvent. The remarkable advantages offered by this method are an inexpensive and easily available catalyst, a simple procedure, mild conditions, and much faster (60–120 min) reactions.     

Stereoselective Glycosidic Coupling Reactions of Fully Benzylated 1,2-Anhydro Sugars with N-Tosyl- or N-Benzyloxycarbonyl-l-serine Methyl Ester

Abstract

The glycosidic coupling reaction of 1,2-anhydro-3,4,6-tri-O-benzyl-β-d-mannopyranose (7), 1,2-anhydro-3,4,6-tri-O-benzyl-α-d-galactopyranose (21), and 1,2-anhydro-3,4-di-O-benzyl-α-d-xylopyranose (18) with N-tosyl- (10) or N-benzyloxycarbonyl- (11) L-serine methyl ester provides a new stereocontrolled synthesis of 1,2-trans linked glycopeptides. The 1,2-anhydro sugars are shown to react smoothyl with 10 or 11 in the presence of Lewis acid (ZnCl₂ or AgOTf) as well as powdered 4A molecular sieves in CH₂Cl₂ at room temperature to afford glycosyl serine derivatives with high stereoselectivity and high yield in less than 30 min. An improved method using 2-O-acetyl-3,4,6-tri-O-benzyl-α-d-mannopyranosyl chloride (6) as the key intermediate for ring closure was applied for the synthesis of 1,2-anhydro-3,4,6-tri-O-benzyl-β-d-mannopyranose.     

Synthesis of Some Bicyclic Thiazolo- and Oxothiazolo-Pyrimidines

Abstract

Oxothiazolopyrimidine compounds 2(a–e) were synthesized under reflux condition by a simple one-pot condensation reaction of the pyrimidine derivative 1 and chloroacetylchloride in the presence of silver acetate as a catalyst. In a similar way the thiazolopyrimidine 3 and oxothiazolopyrimidine 4 were synthesized by reaction of pyrimidine derivative 1 with 1,2-dibromoethane and 2-bromopropanoic acid respectively. The yields of products following recrystallization from ethanol were of the order of 55–89%.      

Simple ammonium ionic liquid catalyses the 1,5-benzodiazepine derivatives under mild conditions

Abstract

An incredibly elementary procedure for the effective synthesis of 1,5-benzodiazepine derivatives using triethyl ammonium acetate (TEAA) [Et₃NH][CH₃COO] ionic liquid has been developed. TEAA was found to be practical, inexpensive, reusable and has a simple work-up procedure, which is absent in other catalyst. The role of TEAA as the reaction medium as well as the catalyst has shown the benefits of the use of TEAA in organic synthesis. The effect of [Et₃NH][CH₃COO] on the synthesis of 1,5-benzodiazepine derivatives has been studied and results are provided herein.     

New Method for the Synthesis of Lactones via Nickel-Catalyzed Isocyanides Insertion

A novel nickel catalyst for the reaction of tert-butyl isocyanide insertion was discovered. In this approach, 1,2-bis(diphenylphosphino)ethane (L3) serves as an efficient ligand, thereby allowing the preparation of lactones from (o-bromophenyl)phenylethanone derivatives. It is noteworthy that this is the first example of nickel acting as a metal catalyst in the reactions of tert-butyl isocyanide insertion. The significance of this methodology may draw many chemists’ attention in the field of isocyanide-incorporating reactions.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

One‐Pot Synthesis of Novel Pyrrolo[1,2‐a]quinoxaline‐4(5H)‐ones Using Benzene‐1,2‐diamine,Acetylenedicarboxylates, and β‐Nitrostyrene Derivatives

The reaction between a variety of o‐phenylenediamines (=benzene‐1,2‐diamines), dialkyl acetylenedicarboxylates, and derivatives of nitrostyrene (=(E)‐(2‐nitroethenyl)benzene) in the presence of sulfamic acid (SA; H₃NSO₃) as catalyst led to the corresponding pyrrolo[1,2‐a]quinoxaline‐4(5H)‐one derivatives in high yields.     

One-pot synthesis of new 6-(alkylamine)dibenzo[c,e][1,2]oxaphosphinine-6-oxides

Several new 6-(alkylamine)-6H-dibenz[c,e][1,2]oxaphosphinine-6-oxides were prepared through a one-pot reaction, starting with 2-phenylphenol, phosphorus trichloride, and a Zn catalyst, to form 6-chloro-6H-dibenz[c,e][1,2]oxaphosphine. The alkylamine derivatives were subsequently prepared through a nucleophilic substitution reaction involving aliphatic amines and H₂O₂ oxidation under soft conditions. This method has the advantages that it is a one-pot synthesis, does not require an inert atmosphere, and involves in situ catalyst formation.     

手性二胺修饰的负载型钌催化剂催化芳香酮不对称加氢

研究了用手性修饰剂(1S,2S)-(－)-1,2-二苯基乙二胺修饰的负载型钌催化剂(Ru/γ-Al₂O₃)催化芳香酮的不对称加氢反应, 在KOH的异丙醇溶液中, 10～20 ℃, p_H2＝5 MPa条件下, 芳香酮及其衍生物加氢产物的ee值达79.5%～85.0%, 2-乙酰基噻吩加氢产物的ee值可达86.2%. 此催化剂制备简单, 容易与产物分离, 重复使用4次, 对映选择性基本保持不变.     

Sulfonated Porous Carbon (SPC)-Catalyzed Synthesis of Benzothiazole Derivatives in Water

Abstract

A simple and efficient procedure has been developed for the synthesis of benzothiazole derivatives in water by the condensation of 2-aminothiophenol with aldehydes in the presence of Sulfonated porous carbon (SPC). This method provides a simple and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst, and simple workup procedure.