V（HSO4）3 catalyzed chemoselectivity acetylation of alcohols and phenols in solution and under solvent-free conditions

A variety of alcohols and phenols are efficiently acetylated with acetic anhydride in the presence of a catalytic amount of V(HSO4)3 in solution and under solvent free conditions.Mild reaction conditions,high yields of the products,easy procedure and selective acetylation of alcohols and phenols in the presence of amines and thiols are the main advantages of this procedure.     

Bi（OTf）3-catalyzed tandem reaction of naphthols with β,γ-unsaturated α-ketoesters. Efficient synthesis of functionalized 4H-chromenes

An efficient synthesis of functionalized 4H-chromenes by the tandem reaction of β,γ-unsaturated α- ketoesters with 2-naphthols, 1 -naphthols, and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi（OTf）3, 5 mol%] under mild conditions. The functionalized 4H-chromene synthesis and our previous 2H- chromene hemiacetal synthesis could complement each other to enrich reaction diversity.     

Yb（OTf）3 Catalyzed Nucleophilic Conjugate Addition of Pyrrole to α，β-Unsaturated Ketones and Nitro-compounds

Under the catalysis of Yb(OTf)3, nucleophilic conjugate addition of pyrrole to electron deficient olefins in CH2Cl2 at ambient temperature gives corresponding 2-alkylated pyrrole derivatives in good yields with high selectivity.     

Covalently anchored sulfonic acid on silica gel （SiO2-R-SO3H） as an efficient and reusable heterogeneous catalyst for the one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions

A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported.All types of aldehydes,including aromatic,unsaturated,and heterocyclic,are used.The silica gel/sulfonic acid catalyst (SiO2-R-SO3H) is completely heterogeneous and can be recycled.     

One-pot synthesis of novel pyrido[2,3-d]pyrimidines using HAp-encapsulated-γ-Fe2O3 supported sulfonic acid nanocatalyst under solvent-free conditions

Novel pyrido[2,3-d]pyrimidine derivatives were synthesized through a one-pot three-component approach using HAp-encapsulated-γ-Fe2O3[γ-Fe2O3@HAp-SO3H]catalyzed condensation of 6-arnino-2-（methylthio or ethylthio）pyrimidin-4（3H）-one,Meldrum＇s acid and aryl aldehydes at 60 ℃ and under solvent-free conditions.In this protocol the use of nanocatalyst provided a green,useful and rapid method to generate the products in short reaction times and excellent yields（88%-94%）.     

Solvent-switchable Acetalization by Yb（OTf）3-Catalyzed Procedures

O,O＇Diethyl acetals were prepared in high yields under mild conditions via the reaction of triethyl orthoformate with aldehydes and ketones in absolute ethanol in the presence of as low as 0.1 tool% of Yb（OTf）3. Using the same catalyst in THF-H2O, these O,O＇-diethyl acetals could be converted to the corresponding carbonyl compounds efficiently. This new protection-deprotection protocol presents the advantages of ease of execution, high efficiency and good chemoselectivity.     

Microwave-assisted synthesis of new N4-[bi-（4-fluorophenyl）- methyl]-piperazine thiosemicarbazones under solvent-free conditions

Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.     

PPh3-catalyzed Mannich reaction: a facile one-pot synthesis of β-amino carbonyl compounds under solvent-free conditions at room temperature

Research on Chemical Intermediates - PPh3 was used as an efficient catalyst for the one-pot three-component Mannich reactions of acetophenone with different aromatic amines and aromatic aldehydes...     

Aerobic oxidation of benzylic aldehydes to acids catalyzed by iron （Ⅲ） meso-tetraphenylporphyrin chloride under ambient conditions

Highly efficient aerobic oxidation of benzylic aldehydes to the corresponding acids catalyzed by iron (Ⅲ) meso-tetraphe- nylporphyrin chloride (Fe(TPP)Cl) under ambient conditions was developed.The catalyst has been proved to be an excellent catalyst for the system in the presence of molecular oxygen and isobutryaldehyde at room temperature.     

Yb(OTf)3-catalyzed synthesis of pyrroles under solvent-tree conditions

Ayb(Otf)3-catalyzed approach for the synthesis of pyrroles under solvent-free conditions was achieved,which could afford the desired products with yields ranged from moderate to excellent.     

An approach to the Paal-Knorr pyrroles synthesis catalyzed by Sc(OTf)3 under solvent-free conditions

A facile synthesis of N-substituted pyrroles by the Paal-Knorr condensation has been accomplished using a simple procedure. Among different metal triflates screened, 1 mol % Sc(OTf)₃ efficiently promoted the reaction to give excellent yield (89-98%) under mild reaction conditions. Additionally, Sc(OTf)₃ could be recovered easily after the reactions and reused without evident loss in activity.     

Silica sulfuric acid (SSA) as a solid acid heterogeneous catalyst for one-pot synthesis of substituted pyrroles under solvent-free conditions at room temperature

A variety of N-substituted pyrroles have been synthesized by reacting γ-diketones with amines, diamines or triamine in the presence of silica sulfuric acid (SSA) at room temperature under solvent-free conditions. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (70-98%).     

Effect of dimethoxyethane in Yb(OTf)3-promoted glycosidations

1,2-Dimethoxyethane (DME) is shown to be a suitable co-solvent for sensibly improving the α-selectivity of glycosidations performed with trihaloacetimidate donors. This solvent works equally well by using either moisture stable Yb(OTf)₃ or standard TMSOTf as the promoters.     

One-pot synthesis of dihydropyrimidiones catalyzed by strontium(II) triflate under solvent-free conditions

A simple, efficient and practical procedure for the Biginelli reaction using strontium(II) triflate [Sr(OTf)₂] as a novel catalyst is described under solvent-free conditions in high yields. The catalyst exhibited remarkable reactivity and it is reusable. Some of dihydropyrimidiones showed strong pesticidal activity.     

Strontium chloride-catalyzed one-pot synthesis of 4(3H)- quinazolinones under solvent-free conditions

<正>Strontium chloride was used as an efficient and recyclable catalyst in one-pot condensation of anthranilic acid,ortho esters and amines leading to the formation of 4(3H)-quinazolinone derivatives in good yields at room temperature under solvent-free conditions.     

Efficient synthesis of bis(indolyl)methanes catalyzed by(PhCH2PPh3)+Br3-under solvent-free conditions

<正>Benzyltriphenylphosphonium tribromide(BTPTB) has been applied as an efficient catalyst for the preparation of bis(indolyl)-methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.     

Ytterbium triflate catalyzed synthesis of chlorinated lactones

The direct synthesis of chlorolactones from differently substituted alkenoic acids, using either sodium hypochlorite or chloramine T as the source of electrophilic chlorine and ytterbium triflate hydrate as the Lewis acid is described. In both cases the reactions proceeded in good yields affording selectively five- or six-membered chlorolactones.     

Microwave-assisted novel synthesis of amino-thieno[3,2-b]pyridines under solvent-free conditions

In the presence of a catalytic amount of ytterbium(III) triflate and under microwave irradiation, mixtures of 2-amino-3-thiophenecarbonitriles, ketones, and silica gel afforded smoothly the corresponding amino-thieno[2,3-b]pyridine derivatives in one step. A wide variety of ketones were tested under these conditions. The reactions proceeded rapidly and afforded the desired products in good to excellent yields.