Synthesis of α-aminonitriles using silica-bonded N-propylpiperazine sulfamic acid as a recyclable catalyst

<正>α-Aminonitriles were synthesized via a one-pot three-component condensation of aldehydes,amines,and trimethylsilyl cyanide using silica-bonded N-propylpiperazine sulfamic acid(SBPPSA) as a recyclable solid acid at room temperature.SBPPSA showed much the same efficiency when used in consecutive reaction runs.     

One-pot three-component synthesis of α-amino nitriles catalyzed by nano powder TiO_2 P 25

A simple and efficient method has been developed for the synthesis ofα-amino nitriles from aldehydes,amines and trimethylsilyl cyanide（Me₃SiCN） in the presence of a catalytic amount of cyanuric acid at room temperature.     

SYNTHESIS AND POLYMERIZATION OF 2-OXO-3-METHYLENE-1,4-DIOXANES

A new kind of monomers was successfully synthesized by the reaction between 2-chloro methyl cycloketal and trimethylsilyl cyanide, followed by ring closure and dehaiogenation. Polymerizations of the monomers were carried out in benzene solution at 80℃with benzoyl peroxide as initiator. Both the structures of monomers and polymers were characterized by IR, ~1H NMR, ~(13)C NMR and elemental analysis.     

硅胶硫酸:一种在温和及无溶剂条件下一锅法合成1,4-二氢吡啶的高效多相催化剂(英文)

A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields,and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.     

一个简单、环境友好的硅胶固载硫酸催化Biginelli反应体系(英文)

A protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and-thiones was developed by means of a three-component condensation of an aldehyde,a β-dicarbonyl compound,and urea or thiourea in acetic acid catalyzed by silica-bonded S-sulfonic acid.Compared to the classical Biginelli reaction conditions,this new protocol has the advantages of consistently excellent yields and short reaction times.After the reaction,the catalyst could be recovered easily and reused with little change in its activity.     

H3PMo12O40 catalyzed three-component one-pot synthesis of 4,6-diarylpyrimidin-2(1H)-ones under solvent-free conditions

<正>4,6-Diarylpyrimidin-2(1H)-one derivatives have been synthesized from three-component one-pot condensation of acetophe-none derivatives,aldehydes and urea in the presence of trimethylsilyl chloride and a catalytic amount of H_3PMo_(12)O_(40)under solvent-free conditions.     

Propylphosphonic anhydride(T3P~) catalyzed one-pot synthesis of α-aminonitriles

The Strecker reaction was performed via a one-pot three component condensation of hetero aromatic/aromatic aldehydes, secondary amines and trimetylsilyl cyanide in the presence of propylphosphonic anhydride(T3P~) to accomplish the corresponding a-aminonitriles. The main advantages of this method are very short reaction time and excellent yields.     

A simple and efficient procedure for the synthesis of optically active s-triazolothiadiazole derivatives

A series of novel s-triazolothiadiazoles 3a-h were prepared by condensation reaction of substituted amino triazoles la-b with N-phethaloyl-L-amino acids 2a-d in the presence of the phosphoroxy chloride（POCl₃） as an anhydrous reagent.The structure of all synthesized compounds was confirmed by IR,¹H NMR,and ¹³C NMR spectroscopy.     

PPA-SiO_2 catalyzed efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation under solvent-free conditions

Silica gel-supported polyphosphoric acid（PPA-SiO₂） was found to be an efficient catalyst for the one-pot four-component Hantzsch condensation reaction of aryl aldehydes,dimedone,ethyl acetoacetate and ammonium acetate to afford the corresponding polyhydroquinoline derivatives in high yields.The main advantages of the present approach are short reaction times,clean reaction profiles,simple experimental and workup procedures.     

Conversion of ethanol to 1,3-butadiene over Ag-ZrO2/SiO2 catalysts:The role of surface interfaces

A series of Ag-ZrO₂/SiO₂ catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ¹H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO₂ improved the interaction between Ag and ZrO₂/SiO₂,creating more Ag^δ+active sites.The high dispersion of ZrO₂ on SiO₂ generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^δ+species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.     

V(HSO_4)_3 promoted oxidation of alcohols and trimethylsilyl,tetrahyropyranyl and methoxymethyl ethers with Cu(NO_3)_2·3H_2O in the absence of solvent

V(HSO_4)_3 has been found to be an efficient reagent for the promotion of the oxidation of alcohols and trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds with Cu(NO_3)_2·3H_2O in the absence of solvent.     

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple,efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride,aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation.The present environmentally benign protocol offers several advantages, such as shorter reaction time,a wide range of fimctional group tolerance,the use of an inexpensive heterogeneous catalyst,and a high yield of products via a simple experimental and work-up procedure.The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template.The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron imcroscopy(TEM).The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.     

A convenient one-step preparation of diaminonitrile compounds

A new method for preparation of diaminonitrile compounds is reported.In this method primary aliphatic diamine compounds were condensed with two equivalents of benzaldehyde and sodium cyanide in presence of an aqueous solution of sodium hydrogensulfite under mild conditions.This method provides an efficient,convenient and practical method for the syntheses of diaminonitrile compounds and the products are easily isolated.The prepared new compounds were characterized by elemental analysis,IR,NMR spectroscop...     

Amides as surrogates of aldehydes for C–C bond formation:amide-based direct Knoevenagel-type condensation reaction and related reactions

Aldehydes are perhaps the most versatile compounds that enable many C–C bond forming reactions, which are not amenable for other subclasses of carbonyl compounds. We report the first use of amides as surrogates of aldehydes for C–C bond formation,namely, the direct Knoevenagel-type condensation based on amides. The one-pot method consists of controlled reduction of an amide with LDBIPA [Li Al H(i Bu)2(Oi Pr)], Lewis acid-mediated release of a reactive iminium ion intermediate, nucleophilic addition, and in situ elimination of amine. The reaction shows good functional group tolerance. We also demonstrated that the Schwartz reagent could be used as an alternative of LDBIPA. The employment of nitromethane and a silyl enol ether as the nucleophiles opens an avenue for the unprecedented amide-based nitro-aldol condensation reaction and aldol condensation reaction, respectively.     

可重复使用的丙磺酸功能化纳米结构SBA-15上醇和酚与六甲基二硅氮烷的硅烷化反应(英文)

Various alcohols and phenols were trimethylsilylated in excellent yields using hexamethyldisilazane in the presence of catalytic amounts of environmentally friendly, hydrophobic, highly thermal stable, and completely heterogeneous sulfonic acid functionalized mesostructured SBA-15 in dichloromethane at ambient temperature. Primary, bulky secondary, tertiary, and phenolic hydroxyl functional groups were transformed to the corresponding trimethylsilyl ethers in excellent yields. The simple experimental procedure was accompanied by easy recovery and the catalyst was reusable (at least 18 reaction cycles); these are attractive features of this protocol.     

An efficient green synthesis of dispirohydroquinolines via a diastereoselective one-pot eight-component reaction

The one-pot eight-component reaction between Meldrum's acid, an aromatic aldehyde, and an aryl amine was achieved in the presence of citric acid catalyst. The corresponding dispirohydroquino-lines were obtained in good yields with excellent diastereoselectivity. This method is a combination of the Knoevenagel and Michael reactions.     

Thermodynamic study of CN~- ion inhibition of Jack bean urease using the extended solvation theory

Cyanide ion was studied as an inhibitor of Jack bean urease at 300 K in 30 mmol/L tris buffer,pH 7.The inhibition was investigated by isothermal titration calorimetry(ITC).The extended solvation model was used for CN~- + JBU interaction over the whole range of CN~- concentrations.The binding parameters recovered from the solvation model were attributed to the cyanide ion interaction.It was found that cyanide ion acted as a non-cooperative inhibitor of urease,and there is a set of 12±0.12 identical and in...     

Promoting condensation kinetics of polymeric carbon nitride for enhanced photocatalytic activities

Polymeric carbon nitride(CN)semiconductor by thermal condensation of N-rich precursors has attracted much attention for its capability ranging from photocatalytic and photoelectrochemical energy conversion to biosensing.However,the influence of condensation process on the final structure of CN was rarely studied,making the condensation kinetic far from be fully optimized.Herein,we report the preparation of CN by a simple condensation kinetics modulation using a faster ramping rate during the polymerization process.The modified condensation recipe was even simpler than the conventional one,but led to an improved photocatalytic H2 evolution up to 3 times without any additional chemicals or other complements.Detailed mechanism studies revealed the increase of crystallinity and surface area due to the rapid condensation played the key roles.This work would offer a more facile and effective way to prepare bulk CN for large-scale industrial applications of bulk CN with higher photocatalytic actives for sustainable energy,environmental and biosensing.     

Fructose-catalyzed synthesis of tetrahydrobenzo[b]pyran derivatives：Investigation of kinetics and mechanism

Fructose was used as an efficient catalyst for three-component condensation reactions of aryl alde-hydes, malononitrile, and dimedone in a mixture of EtOH and H2O as green solvents. The advantages of t...     

One-pot synthesis of tri- and tetra-substituted imidazoles using sodium dihydrogen phosphate under solvent-free conditions

<正>Sodium dihydrogen phosphate(NaH_2PO_4) efficiently catalyzes the condensation reaction of benzil,aldehydes,amines and ammonium acetate in a four-component reaction under solvent-free conditions.The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields.Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil,aldehydes and ammonium acetate using NaH_2PO_4.