An Efficient Procedure for Esterification of Aryloxyacetic Acid and Arylthioacetic Acid Catalyzed by Silica Sulfuric Acid

Aryloxyacetate and arylthioacetate are wildly used in herbicides, plant regulator and insecticides. Recently, Wille et al. have reported that methyl aryloxyacetate is an efficient agent to prevent and treat allergic contact dermatitis.[1] The most popular synthesis is by heating sodium phenoxide (mercaptide) with ethyl chloroacetate in DMF,[2] or by the esterification of acid with alcohol using concentrated H2SO4 as catalyst.[3] In this paper, synthesis of aryloxyacetate and aryl thioacetate from aryloxyacetic acid and arylthioacetic acid respectively in ether catalyzed by silica sulfuric acid in 83%～94% yields is described. The catalyst is reused for 3 times without significant loss of activity (Entry 4). Compared with common procedures, the present procedure possesses the advantages of the operational simplicity, short reaction time,less-corrosion, high yield and reusable catalyst.     

An Efficient Method for the Synthesis of Acylals from Aldehydes under Solvent‐Free Conditions Catalyzed by Antimony Trichloride

A mild and efficient method has been developed for the preparation of acylals from aldehydes catalyzed by antimony trichloride under solvent‐free conditions in very good to excellent yields. The easy availability, low cost, and ease of handling of the catalyst make this procedure especially attractive for large‐scale synthesis.     

Mild and Efficient Procedure for the Synthesis of 1,5‐Benzodiazepines Catalyzed by Magnesium Perchlorate

A convenient and efficient method for the synthesis of 1,5‐benzodiazepines by the reaction of o‐phenylenediamines (OPDA) and ketones with hydrogens at the α‐position has been developed. The reaction is carried out at room in the presence of a catalytic amount of magnesium perchlorate under solvent‐free conditions.     

An Efficient Synthesis of Aromatic 1-Hydroxymethylene-1,1-bisphosphonates from Aldehydes

A simple and efficient procedure for synthesis of 1-hydroxymethylene-1,1-bisphosphoates from aldchydes is described.This method was applied to the synthesis of novel catechol substituted bisphosphonates as the anti-osteoporosis agents.     

An Efficient and Environment Friendly Procedure for the Synthesis of Arylmethylenemalononitrile Catalyzed by Strong Base Anion‐Exchange Resin in Water

Abstract

Knoevenagel condensation of malononitrile with aromatic aldehydes catalyzed by strong base anion‐exchange resin in water results arylmethylenemalononitrile in 74–98% yield at room temperature.     

Efficient and Convenient Procedure for Preparation of N‐Sulfonylimines Catalyzed by Montmorillonite K‐10

A general and practical chemical route to the synthesis of N‐sulfonylimines using montmorillonite K‐10 as the catalyst is described. This method provides several advantages such as operational simplicity, short reaction time, using of inexpensive materials, noncorrosivity, lack of pollution, and high yields.     

Practical and Phase Transfer–Catalyzed Synthesis of 6‐Methoxytryptamine

A convenient and cost‐effective synthesis of 6‐methoxytryptamine (1), starting from commercially available phthalimide and 1‐bromo‐3‐chloropropane via PTC N‐alkylation, PTC C‐alkylation, Japp–Klingemann reaction, hydrolysis, and decarboxylation, has been accomplished with a 44% overall yield.     

Simple and Efficient Procedure for the One‐Pot Synthesis of β‐Acetamido‐β‐aryl‐propiophenones by Molecular Iodine–Catalyzed Tandem Reaction

Molecular iodine efficiently catalyzes the four‐component tandem reaction of araldehydes, arylmethyl ketones, acetyl chloride, and acetonitrile to afford the corresponding β‐acetamido‐β‐aryl‐propiophenones. The new protocol gives high yields of the products, and the reactions go to completion within 10–15 min on a hot plate at 80–85°C.     

Perchloric Acid Supported on Silica Catalyzed Efficient Synthesis of 1,5‐Benzodiazepines

Perchloric acid adsorbed on silica gel efficiently catalyzed the condensation of o‐phenylenediamines (OPDA) with cyclic and acyclic ketones at ambient temperature to afford 1,5‐benzodiazepines in good yields under solvent‐free conditions.     

An Efficient and Green Procedure for the Preparation ofgem-Dicar-boxylates from Aldehydes Catalyzed by Fe2（SO4）3＂xH20

An efficient and environmentally benign conversion of aldehydes into the corresponding gem-dicarboxylates was realized by using hydrated ferric sulfate as a heterogeneous catalyst. In addition to its high efficiency, the catalyst can be recovered simply and reused efficiently for at least seven times.     

Mild and Efficient Synthesis of bis‐Indolylmethanes Catalyzed by Tetrabutylammonium Tribromide

A mild and efficient electrophilic substitution reaction of indoles with various aldehydes under a catalytic amount of tetrabutylammonium tribromide (TBATB) afforded biologically important bis‐indolymethanes in good yields.     

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.     

RuCl3 · xH2O: A New Efficient Catalyst for Facile Preparation of 1,1‐Diacetates from Aldehydes

An efficient, facile preparation of aldehyde 1,1‐diacetates (acylals) in excellent yields catalyzed by RuCl₃ · xH₂O is described. Ketones do not react under these conditions.     

PEG‐Supported Sulfonic Acid as an Efficient and Recyclable Catalyst for the Synthesis of 1,1‐Diacetates under Solvent‐Free Conditions

An operationally simple, efficient, and environmentally benign synthesis of 1,1‐diacetates in good yields by reaction of different aldehydes with acetic anhydride in the presence of PEG‐supported sulfonic acid under solvent‐free conditions is described.     

Efficient Synthesis of 1,5‐Benzodiazepine Derivatives by Ytterbium Trichloride–Catalyzed Condensation of o‐Phenylenediamine and Ketones

1,5‐Benzodiazepines are synthesized in good to excellent yields by ytterbium trichloride (YbCl₃)–catalyzed condensation of o‐phenylenediamine and ketones under mild and solvent‐free conditions. The Lewis acid–type catalyst, ytterbium trichloride, is found to be water stable and reusable.     

A Mild and Efficient Synthesis of bis‐Indolylmethanes Catalyzed by Sulfamic Acid

A mild and efficient electrophilic substitution reaction of indoles with various aldehydes under catalysis of sulfamic acid afforded biologically important bis‐indolymethanes in good yields.     

An Efficient and Green Procedure for the Preparation of gem-Dicar- boxylates from Aldehydes Catalyzed by Fe_2(SO_4)_3·xH_2O

~~An Efficient and Green Procedure for the Preparation of gem-Dicar- boxylates from Aldehydes Catalyzed by Fe_2(SO_4)_3·xH_2O~~     

A Mild and Practical Procedure for Tetrahydropyranylation of Alcohols and Phenols Catalysed by Anhydrous Ferrous Sulfate

Theprotectionofhydroxybyformationoftetrahydropyranyl(THP)ethersisofgreatimportanceinorganicsynhesisparticularlyduringthesynthesisofnaturalproducts.'OwingtotheremarkablestabilityofTHPethersunderavarietyofreactionconditions,suchasneutralandstronglybasicmedia,reactionsinvolvingGrignardreagents,reductionwithhydrides,oxidation,oxidativealkylationandacylation,etc.,tetrahydropyranylationisoneofthemethodsofchoicetoprotectahydroxylgroupsinamultisteporganicsynthesis.'Generallytetrahydropyranylationofa…     

Dodecatungstophosphoric Acid (H3PW12O40): A Novel and Efficient Recyclable Catalyst for Synthesis of 1,1‐Diacetates from Aromatic Aldehydes in Solvent‐Free System and Their Deprotection

A facile and efficient method for the formation of 1,1‐diacetates from a variety of aldehydes in the presence of a catalytic amount of H₃PW₁₂O₄₀ and acetic anhydride was achieved in good yields at room temperature. The deprotection of the resulting acylals is achieved using the same catalyst in acetone.     

Caro's Acid–Silica Gel: An Efficient and Versatile Catalyst for the One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives

An efficient one-pot synthesis of tetrahydrobenzo[b]pyran is described. This involved the three-component reaction of aromatic aldehydes, molononitrile, and dimedone in the presence of a catalytic amount of Caro's acid supported on silica gel in ethanol/water under reflux.