Rhodium-catalyzed Reformatsky-type reaction of ethyl bromodifluoroacetate

Treatment of a variety of carbonyl compounds with ethyl bromodifluoroacetate and Et₂Zn in the presence of RhCl(PPh₃)₃ in CH₃CN afforded Reformatsky-type products in good to excellent yields in a mild reaction condition. This is a good method to obtain a β-hydroxy-α,α-difluoro carboxylic acid ethyl ester and especially to improve the poor reactivity of ketones.     

One-pot synthesis of 3,4-Dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones (thiones) promoted by nano-BF<Subscript>3</Subscript>.SiO<Subscript>2</Subscript>

3,4-Dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thione were synthesized under solvent free condition in the presence of nano-silica supported boron trifluoride (nano-BF₃.SiO₂). The reactions were carried out at 80 °C for 15 min under solvent free condition. This methods have some advantages such as good to excellent yield, mild reaction condition, ease of operation and workup, short reaction time and high product purity.     

Application of DMF-methyl sulfate adduct in the regioselective synthesis of 3-acylated indolizines

A number of 3-acylated indolizines were synthesized in good to excellent yields by a newly established reaction between picolinium salts and the methylsulfate salt of A (R = Me), the adduct formed from DMF-Me₂SO₄ as the key reagent. The low cost, short reaction time, mild reaction condition, and easy purification of the products make this an attractive new method for the synthesis of indolizine compounds. A variety of functional groups (nitro, cyano, ester, methoxy, and halogens) were well tolerated under the reaction conditions.     

Divergent synthesis of fused Benzo-xanthene and oxazine derivatives via Cu-catalyst

Cu-Cu₂O combination showed synergic effects in catalyzing intramolecular Ullmann coupling reaction for halo-Betti bases to afford fused benzo-xanthenes from both electron-rich and electron-deficient aromatic systems in good yield under mild reaction conditions. The sterically hindered halo-Betti bases also provided products in excellent yield. Under optimized condition, a gram scale reaction was also performed to afford the product in excellent yield. However, without ortho-halo substituted Betti-bases failed to afford fused benzo-xanthene derivatives. Exploring the reaction optimization without Cu metal, serendipitously it was produced 1,3-oxazine derivatives in excellent yield via intramolecular cross-dehydrogenative coupling (CDC) reaction. Similarly, electron-rich, electron-deficient and sterically hindered Betti-bases provided the products in good to excellent yield under mild condition.     

A novel amino acid functionalized ionic liquid promoted one-pot solvent-free synthesis of 3,4-dihydropyrimidin-2-(1H)-thiones

An environmentally benign, cheap and reusable L-amino acid functionalized ionic liquid [L-AAIL]/AlCl₃ was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-thione derivatives in good to excellent yield under solvent-free condition. Compared with the classical Biginelli reactions, this method consistently enjoys the advantages of mild reaction conditions, easy work-up, and short reaction time. These one-pot three-component Biginelli products could be separated easily from the catalyst–water system, and the catalyst could be reused at least five times without noticeably reducing catalytic activity.     

无溶剂条件下合成2-[3-氧代-1,3-二(未)取代苯基丙基]-1,2,3,4-四氢萘-1-酮

以3,4-二氢-1-萘酮和查尔酮为原料, 在 K₂CO₃-NaOH 存在下, 无溶剂室温研磨反应, 方便地得到2-[3-氧代-1,3-二(未)取代苯基丙基]-1,2,3,4-四氢萘-1-酮. 该方法具有反应条件温和、操作简单和产率较高等优点, 并通过IR, ¹H NMR, 元素分析确定了产物的结构, 3b晶体结构通过X衍射测定.     

Applications of iron and nickel immobilized on hydroxyapatite‐core‐shell γ‐Fe2O3 as a nanomagnetic catalyst for the chemoselective oxidation of sulfides to sulfoxides under solvent‐free conditions

In the present study, Fe²⁺ and Ni²⁺ immobilized on hydroxyapatite‐core‐shell γ‐Fe₂O₃ (γ‐Fe₂O₃@HAp‐Fe²⁺ and γ‐Fe₂O₃@HAp‐Ni²⁺) with a high surface area has been synthesized and characterized by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and scanning electron microscope (SEM) techniques. Then, γ‐Fe₂O₃@HAp‐Fe²⁺ and γ‐Fe₂O₃@HAp‐Ni²⁺ were used as a new and magnetically recoverable nano catalyst for the selective oxidation of sulfides to sulfoxides with 33% aqueous H₂O₂ (0.5 mL) as an oxidant at room temperature in good to excellent yields and short reaction time. Nontoxicity of reagent, mild reaction condition, inexpensive and high catalytic activity, simple experimental procedure, short period of conversion and excellent yields, and ease of recovery from the reaction mixture using an external magnet are the advantages of the present method.     

Synthesis of 3-methyl-2-cyclohexenones catalyzed by mercury(II) salts and their microwave assisted BiCl3 catalyzed aldol condensations

HgSO₄ catalyzed hydrative cyclization of 1,6-heptadiynes is present. This reaction proceeded smoothly under the mild condition for differently 4-sustituted 1,6-diynic substrates giving corresponding 3-methyl-2-cyclohexenones with high to excellent yield. The microwave assisted aldol condensation of cyclohexenones under the catalysis of BiCl₃ afforded 3-styryl-cyclohexenones with high regio- and stereo-selectivity.     

Catalytic Sc(OTf)3 mediated direct asymmetric aldol reaction of (−)-menthyl isothiocyanatoacetate with aldehydes by using (−)-menthol as chiral auxiliary

This method involves the direct asymmetric aldol reaction of (−)-menthyl isothiocyanatoacetate 5 with a variety of substituted aromatic aldehydes, which offers a convenient method for the synthesis of intermediate containing biologically relevant α-amino β-hydroxyl groups in oxazolidine ring. In this methodology, the products show remarkable diastereoselectivity using Sc(OTf)₃ as a catalyst and easily accessible (−)-menthol as a chiral auxiliary. This approach includes some important aspects such as mild reaction conditions, high yields, and excellent diastereoselectivity with a number of substituted aromatic aldehydes. The optimization and effect of different catalysts were studied at different reaction conditions and it is found that Sc(OTf)₃ shows excellent diastereoselectivity at −45°C.     

Rapid and Efficient Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-yl)-2H-acenaphthen-1-ones Catalyzed by p-TSA

An efficient synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones and 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones via a reaction of various isatins or acenaphthenequinone with indoles in the presence of p-methylbenzene sulfonic acid (p-TSA) in CH₂Cl₂ at room temperature is described. The advantages of this method include good reaction yield, simple workup procedure, and mild reaction condition.     

Highly selective and efficient oxidation of sulfides with hydrogen peroxide catalyzed by a chromium substituted Keggin type polyoxometalate

The catalytic oxidation of sulfides into the corresponding sulfones by a chromium substituted Keggin type polyoxometalate, (TBA)₄[PW₁₁CrO₃₉]·3H₂O, was achieved using mild reaction conditions. Excellent yields were obtained using four equivalents of 30% H₂O₂. Under these reaction conditions, the sulfide group was highly reactive and other functional groups such as hydroxyl or a double bond were unaffected. Using a commercially available, eco-friendly, and cheap oxidant, mild reaction conditions, operational simplicity, practicality, short reaction times, high to excellent yields, and excellent chemoselectivity are some of the advantages of this catalytic system.     

Highly efficient Pd(acac)2/TFA catalyzed head-to-tail dimerization of vinylarenes at room temperature

Pd(acac)₂ catalyzed dimerization of vinylarenes to form dimers under mild condition with excellent yields and stereoselectivities. In particular, the use of TFA highly promoted the activity and selectivity of the dimerization. The studies on mechanism for the reaction displayed clearly that the dimerization of styrenes is 100% atom economic reaction.     

Magnetically recoverable γ-Fe2O3 nanoparticles as a highly active catalyst for Friedel–Crafts benzoylation reaction under ultrasound irradiation

A simple, facile and efficient method has been developed for the Friedel–Crafts benzoylation of arenes using magnetic γ-Fe₂O₃ nanoparticles under solvent-free sonication. The γ-Fe₂O₃ nanoparticles were used as an efficient and magnetically recoverable catalyst for the synthesis of aromatic ketones in good to excellent yields at room temperature under solvent-free. The reaction occurred with high regioselectivity under mild condition. The magnetic γ-Fe₂O₃ nanoparticles are economically synthesized in large-scale, easily separated from the reaction mixture by an external magnet and able to be reused several times without significant loss of the catalytic performance, which make them easy application to industrial processes.     

Simple and Friendly Sulfones Synthesis Using Aqueous Hydrogen Peroxide with a Reusable Keggin Molybdenum Heteropolyacid,Immobilized on Aminopropyl-Functionalized Silica

Keggin molybdenum heteropolyacid (H₃PMo₁₂O₄₀), immobilized on aminopropyl-functionalized silica catalysts, were made using two immobilization methods: incipient wetness and equilibrium adsorption. The material prepared for the equilibrium adsorption technique was found to be a highly efficient, ecofriendly, and recyclable heterogeneous catalyst for the selective oxidation of sulfides to sulfones in excellent yields, under mild reaction condition using 35% w/v aqueous hydrogen peroxide as the oxidant.     

Sulfamic acid: an efficient, cost-effective and recyclable solid acid catalyst for the Friedlander quinoline synthesis

o-Aminoaryl ketones undergo smooth condensation with α-methylene ketones in the presence of sulfamic acid (NH₂SO₃H) (SA) under mild reaction conditions to afford the corresponding polysubstituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective and environmentally benign.     

A rapid, solvent-free, ligandless and mild method for preparing aromatic ketones from acyl chlorides and arylboronic acids via a Suzuki-Miyaura type of coupling reaction

Aromatic ketones were synthesized via a palladium catalyzed cross-coupling reaction of boronic acids with acyl chlorides in the presence of Na₂CO₃ at room temperature under solvent-free conditions. The ligand-free and mild reaction conditions, highly rapid reaction rate and good to excellent yields are important features of this method.     

A green and practical method for the synthesis of novel pyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazoles and <Emphasis Type="Italic">bis</Emphasis>-pyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazoles using sulfonic acid-functionalized ionic liquid

An efficient and practical protocol was developed for the synthesis of novel pyrano[2,3-c]pyrazoles and bis-pyrano[2,3-c]pyrazoles by one-pot four-component reaction of arylaldehyde, ethyl acetoacetate, hydrazine hydrate and dimethyl malonate using SO₃H-functionalized ionic liquid [DMBSI]HSO₄ as a potential green catalyst under solvent-free condition. The method presented is mild, environmentally friendly, inexpensive and functionality tolerant and produces the desired pyranopyrazoles in short reaction times (17–24 min) and excellent yields (85–95%). In addition, the catalyst can be reused at least ten times without almost any change in its catalytic activity.     

Facile and Versatile Synthesis of Alkyl and Aryl Isothiocyanates by Using Triphosgene and CoSolvent

A mild and efficient method for the conversion of alkyl and aryl amines to isothiocyanates via dithiocarbamates has been developed using (CH₃)₂CO-CS₂ as co-solvent and triphosgene as dehydrosulfurization reagent. High yields, mild reaction conditions and excellent functional group compatibility make it become a versatile synthetic method for the preparation of isothiocyanates compared with reported methods.

[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.]     

Catalyst-free aminobromination of alkenes with N-methyl-p-toluenesulfonamide as nitrogen resource

A catalyst-free electrophilic aminobromination system was described with N-methyl-p-toluenesulfonamide (p-TsNHCH₃) and N-bromosuccinimide (NBS) as nitrogen and bromine resources. The reaction can give vicinal haloamines in good yields, excellent regioselectivities, and stereoselectivities under convenient and mild condition. The existence of N-methyl group in the nitrogen resource was found to play an important role in the formation of vicinal haloamine product.     

Cufe2O4 Nanoparticles: A Magnetically Retrievable Catalyst for Green Synthesis of Novel 2-(3-(Dicyanomethyl)-2-Oxoindolin-3-Ylthio)Acetic Acids

Abstract

A highly efficient and green method for the synthesis of new 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids is described using magnetically recoverable and reusable CuFe₂O₄ nanoparticles. A wide variety of aryl isatylidene malononitrils underwent Micheal addition with thioacids to afford novel 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids in good to excellent yields. The reaction protocol is operationally simple and mild. Moreover, water as solvent makes the reaction procedure eco-friendly and economically viable. All products were characterized by NMR and IR spectroscopies.