ZSM-5-SO3H as a novel, efficient, and reusable catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions

Abstract  

ZSM-5 has been modified as supported sulfuric acid (ZSM-5-SO₃H) and introduced for the first time as a mild, convenient, reusable, and heterogeneous catalyst. Various types of aldehydes were efficiently converted to their 1,1-diacetates using a catalytic amount of ZSM-5-SO₃H in excellent yields under solvent-free and heterogeneous conditions at room temperature. The deprotection of 1,1-diacetates has also been achieved using this novel catalyst in ethanol. The procedure is operationally simple, environmentally benign, and only a stoichiometric amount of anhydride is used.     

PHOSPHORUS PENTOXIDE-MONTMORILLONITE K-10 AS CATALYST FOR THE PREPARATION OF 1,1-DIACETATES UNDER SOLVENT-FREE CONDITIONS

A facile and efficient method for the preparation of 1,1-diacetates of aldehydes is improved. P₂O₅/montmorillonite K10 catalyzed 1,1-diacetates formation from aldehydes in dry media. Both aromatic and aliphatic aldehydes gave high yields (70–95%) of the corresponding 1,1-diacetates. Advantages of this method are the use of an inexpensive and selective catalyst, with high yields in simple operation and short reaction time under solvent-free conditions.     

Solvent-free catalytic preparation of 1,1-diacetates from aldehydes using a Wells-Dawson acid (H6P2W18O62·24H2O)

Aromatic and aliphatic aldehydes are transformed in 1,1-diacetates (acylals) in mild conditions, by a treatment with acetic anhydride and a Wells-Dawson acid (H₆P₂W₁₈O₆₂·24H₂O). gem-Diacetylation proceeds in Ac₂O with a little as 1% mol Wells-Dawson acid at room temperature and under solventless conditions, obtaining very good to excellent yields (88-98%) of 1,1-diacetates (19 examples). Neither 4-dimethylaminobenzaldehyde nor ketones react under the same conditions.     

Microwave-assisted solvent-free synthesis of 1,1-diacetates catalyzed by SbCl3 from aldehydes and acetic anhydride

Microwave-assisted synthesis of a variety of 1,1-diacetates catalyzed by SbCl₃ from corresponding aldehydes and acetic anhydride was reported. Only 10 mol% of catalyst was sufficient to push the reaction forward and high amounts of the catalyst did not improve the yields to a great extent. The present protocol offered several advantages including low cost of the catalyst, high yields, short reaction time and simple work-up procedure.     

从醛无溶剂制备1,1-二乙酸酯的催化剂Cu3/2PMo12O40/SiO2

芳香醛和脂肪醛在温和条件下经乙酸酐和Cu3/2PMo12O40/SiO2催化可转变成 1,1-二乙酸酯. 发现Cu3/2PMo12O40/SiO2是在无溶剂存在下制备 1,1-二乙酸酯的有效催化剂. 使用同一催化剂和乙腈作溶剂可使生成的 1,1-二乙酸酯发生逆反应脱保护生成醛. 这种新的方法具有反应时间短和收率高的优点,而且催化剂重复使用几次不丧失活性.     

NbCl5 as an Efficient Catalyst for Chemoselective Synthesis of 1,1-Diacetates Under Solvent-Free Conditions

A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by NbCl₅(5 mmol%) under solvent-free conditions has been developed. The yields are in the range of 93–98%. This protocol offered several advantages, including low catalyst loading, good yields, short reaction times, and environmentally friendliness.     

离子液体促进四氟硼酸铜催化芳醛和乙酸酐合成1,1-二乙酸酯

在室温条件下, 离子液体1-正丁基-3-甲基六氟磷酸盐([bmim]PF₆)能促进四氟硼酸铜催化一系列芳醛和乙酸酐反应, 以83%～97%的产率生成相应的1,1-二乙酸酯. 在离子液体[bmim]PF₆存在情况下, 催化剂活性远远高于无离子液体存在下的活性. 催化剂用量仅需 0.2 mol%就能使反应顺利进行, 远远少于文献报道的其它催化剂的用量, 反应在3～20 min内完成. 实验结果表明该法催化剂用量少、产率高、反应时间短、离子液体可重复使用、对环境友好.     

Investigation of the catalytic activity of an electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for ring-opening of epoxides

In this work, the catalytic activity of high-valent tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V^IV(TPP)(OTf)₂], in the nucleophilic ring-opening of epoxides is reported. This new V(IV) catalyst was used as an efficient catalyst for alcoholysis with primary (methanol, ethanol and n-propanol), secondary (iso-propanol) and tertiary alcohols (tert-butanol), hydrolysis and acetolysis of epoxides with acetic acid and also for the conversion of epoxides to 1,2-diacetates with acetic anhydride, conversion of epoxides to thiiranes with ammonium thiocyanate and thiourea, and for conversion of epoxides to acetonides with acetone. The catalyst was reused several times without loss of its activity.     

P4VP-H2SO4-Catalyzed Chemoselective Protection of Aldehydes to Acylal Along with Deprotection Reactions

Poly(4-vinylpyridine)-supported sulfuric acid is an excellent reusable heterogeneous catalyst for the chemoselective synthesis of 1,1-diacetates(acylal) from aldehydes in dichloromethane at room temperature within a few minutes. The protection of salicyaldehyde generated an anhydro-dimer as single product under similar reaction conditions. The catalyst is equally applicable for the deprotection of acylal in acetonitrile. The catalyst was prepared by the wet impregnation technique.     

A highly efficient protocol for regioselective ring-opening of epoxides with alcohols,water, acetic acid,and acetic anhydride catalyzed by SbF3

SbF₃ as an efficient catalyst has been used for regioselective alcoholysis, acetolysis and hydrolysis of epoxides to the corresponding β-alkoxy, β-acetoxy alcohols, and 1,2-diols in high to excellent yields. This study also represents a convenient synthesis of vic-diacetates from ring-opening of epoxides with acetic anhydride.     

Silica-bonded S-sulfonic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates

A simple and efficient procedure for the preparation of silica-bonded S-sulfonic acid (SBSSA) by reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform is described. This solid acid is employed as a recyclable catalyst for the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature.     

BiVO<Subscript>4</Subscript>-NPs: an efficient nano-catalyst for the synthesis of biscoumarins,bis(indolyl)methanes and 3,4-dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones (thiones) derivatives

BiVO₄-NPs can be used as an efficient and reusable nano-catalyst for the promotion of the synthesis of biscoumarins, bis(indolyl)methanes and 3,4-dihydropyrimidin-2(1H)-ones (thiones) derivatives. The structures of the products were characterized by IR, ¹H NMR and ¹³C NMR spectroscopy and comparison with the authentic samples. Easy work-up procedure, excellent yields, short reaction times and reusability of the catalyst are some advantages of this work. In addition, in this article and for the first time, the preparation of 3,4-dihydropyrimidin-2(1H)-ones and -thiones from the protected derivatives of aldehydes including oximes, semicarbazones and 1,1-diacetates is reported.     

An imidazolium ionic liquid having covalently attached an oxime carbapalladacycle complex as ionophilic heterogeneous catalysts for the Heck and Suzuki-Miyaura cross-coupling

An oxime carbapalladacycle, analogous to that used as catalyst in homogeneous phase, has been derivatized to increase its ionophilicity by introducing an imidazolium group covalently attached through a chain at the complex. The resulting complex is soluble in 1-butyl-3-methylimidazolium ionic liquid (bmimPF₆) and not extractable by ether. The catalytic activity of this palladium complex in bmimPF₆ is, however, unsatisfactory and only increases marginally in bmimPF₆/supercritical CO₂. This limitation has been overcome by supporting this imidazolium palladium complex on high surface area Al/MCM-41 aluminosilicate, whereby a solid active catalyst for the Suzuki cross-coupling has been obtained. Reusability and stability over reuse for this Al/MCM-41-supported catalyst have been studied.     

一种快速高效分解1,1-二乙酸酯的方法

研究了硅胶硫酸酯催化下1,1-二乙酸酯的分解反应. 该方法具有操作简单、反应时间短、收率高、无污染、催化剂可回收重复使用等特点.     

炭载Pd-Fe合金催化剂的制备及电催化氧还原活性

研究了用NH₄Cl作配位剂的配位还原法来制备的Pd-Fe/C催化剂,发现由于NH₄Cl能与Pd形成配合物,使PdCl₂的还原电位负移,与FeCl₃的还原电位接近,从而在低温下制备得到了高合金化程度的Pd-Fe/C催化剂。XPS表征结果表明:Pd与Fe形成合金后,Pd的电荷密度的减少,增加了Pd⁰的含量。因此,得到的Pd-Fe/C催化剂对氧还原的电催化活性比用相同方法制得的Pd/C催化剂高,而且该催化剂对甲醇氧化没有电催化活性。     

炭载Pd-Fe合金催化剂的制备及电催化氧还原活性

研究了用NH4Cl作配位剂的配位还原法来制备的Pd-Fe/C催化剂,发现由于NH4Cl能与Pd形成配合物,使Pd Cl2的还原电位负移,与Fe Cl3的还原电位接近,从而在低温下制备得到了高合金化程度的Pd-Fe/C催化剂。XPS表征结果表明:Pd与Fe形成合金后,Pd的电荷密度的减少,增加了Pd0的含量。因此,得到的Pd-Fe/C催化剂对氧还原的电催化活性比用相同方法制得的Pd/C催化剂高,而且该催化剂对甲醇氧化没有电催化活性。     

2,6-Dicarboxypyridinium Chlorochromate. An Efficient and Selective Reagent for the Mild Deprotection of Acetals, Thioacetals, and 1,1-Diacetates to Carbonyl Compounds

Summary. 2,6-Dicarboxypyridinium chlorochromate (2,6-DCPCC) was found to be an efficient reagent for the conversion of acetals, thioacetals, and 1,1-diacetates to their corresponding carbonyl compounds under neutral and anhydrous conditions in good to excellent yields. Selective deprotection of acetals or 1,1-diacetates in the presence of thioacetals at room temperature is also observed with this reagent.     

Cupric Sulfate Pentahydrate: A Mild and Efficient Catalyst for the Chemoselective Synthesis of 1,1-Diacetates from Aldehydes in a Solvent-Free System

Cupric sulfate pentahydrate was found to be an efficient catalyst for the protection of aldehydes as 1,1-diacetates in high yields in a solvent-free system at room temperature. Ketones are not affected under these reaction conditions.     

Cupric Sulfate Pentahydrate: A Mild and Efficient Catalyst for the Chemoselective Synthesis of 1,1-Diacetates from Aldehydes in a Solvent-Free System

Summary. Cupric sulfate pentahydrate was found to be an efficient catalyst for the protection of aldehydes as 1,1-diacetates in high yields in a solvent-free system at room temperature. Ketones are not affected under these reaction conditions.     

A New and Efficient Procedure for the Production of 1,1-Diacetate from Corresponding Aldehydes Promoted by Silica Chromate (SiO2-O-CrO2-O-SiO2)

Abstract

A wide range of aromatic aldehydes has been selectively converted to 1,1-diacetates using silica chromate (SiO₂?O?CrO₂?O?SiO₂) under solvent-free conditions at room temperature in moderate to good yields. This protocol is mild and efficient compared to other reported methods.

GRAPHICAL ABSTRACT