An efficient, transition-metal-free process for the synthesis of substituted dihydrofurans via a Michael/cyclization tandem reaction

An efficient green route for the synthesis of substituted dihydrofurans was developed through a simple base-catalyzed, tandem reaction of nitrostyrene with 1,3-dicarbonyl compounds. The desired products were prepared with a large substrate scope and in excellent yields (up to 95%).     

An efficient three-component protocol for the synthesis of novel spiro-oxazinobarbiturates

Some novel spiro-oxazinobarbiturate derivatives have been successfully synthesized in a one-pot, three-component cascade reaction from various azines (pyridine, isoquinoline, quinoline and phenanthridine), 1,3-dimethylalloxan, and several activated acetylenes (alkyl propiolates, dialkyl acetylenedicarboxylates, and butyne-2-one). The high bond forming efficiency (formation of new C-N, C-C, and C-O bonds) of this reaction makes it attractive for the synthesis of spiro-oxazinobarbiturates in a single operation.     

An efficient organocatalyzed multicomponent synthesis of diarylmethanes via Mannich type Friedel-Crafts reaction

We have developed an efficient organocatalyzed, multicomponent synthesis of diarylmethane derivatives from tertiary aromatic amines, formaldehyde and 2-naphthols via Mannich type Friedel-Crafts reaction. Several organocatalysts such as (−)-chinchonidine, l-proline, l-thiaproline, and l-pipecolonic acid have been screened for the reaction but the best results were obtained with l-proline. In this Mannich type Friedel-Crafts alkylation, tertiary aromatic amines react with formaldehyde-proline adduct to generate 1-(4-(dimethylamino)benzyl)pyrrolidinium-2-carboxylate intermediate, which undergoes nucleophilic addition to give substituted diarylmethanes in excellent yields.     

A new sustainable protocol for the synthesis of nitroaldol derivatives via Henry reaction under solvent-free conditions

A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives.     

Extension of the Willgerodt-Kindler reaction: protected carbonyl compounds as efficient substrates for this reaction

Nitrogen derivatives of carbonyl compounds such as oximes, hydrazones, and semicarbazones were found to be excellent candidates for the Willgerodt-Kindler reaction. They can be used directly in a solvent-free reaction, under both classical and microwave conditions, to give the corresponding thiomorpholides in good yields.     

An efficient ZnO-catalyzed synthesis of novel indole-annulated thiopyrano-chromene derivatives via Domino Knoevenagel-hetero-Diels-Alder reaction

An efficient synthesis of pentacyclic indole derivatives is achieved via domino Knoevenagel-hetero-Diels-Alder reactions of indolin-2-thiones and O-propargylated salicylaldehyde derivatives in CH₃CN in the presence of 10 mol % of ZnO as a heterogeneous catalyst. The products are formed in good to excellent yields.     

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.     

An efficient one-pot method for the synthesis of novel ferrocene-triamide conjugates via pseudo five-component reaction

A simple and efficient one-pot synthesis of novel ferrocene-triamide conjugates from the reaction of ferrocenecarboxaldehyde with Meldrum’s acid and isocyanides in the presence of NH-containing compounds is described. This transformation proceeds through the creation of two CC bonds, two CN bonds, and one CO bond, leading to three peptide bonds, and presumably occurs via a domino sequence involving Knoevenagel condensation, [1+4] cycloaddition, deacetonation, and aminolysis reactions.     

Highly stereo and chemoselective synthesis of tetra and pentacyclic frameworks using Solid-State Melt Reaction (SSMR)

Benzopyran fused tetra and pentacyclic frameworks have been synthesized by the domino Knoevenagel hetero Diels–Alder (DKHDA) reaction using various 1,3-diones with O-allylated salicylaldehydes and O-propargylated salicylaldehydes in a solvent and catalyst free condition via Solid-State Melt Reaction (SSMR). The reaction requires only a single step operation thus providing potentially bioactive polycyclic heterocycles in high yields.     

熔融聚合法合成生物材料聚(乳酸-丙氨酸)

直接以乳酸、丙氨酸为原料,通过熔融聚合法合成生物降解材料聚(乳酸-丙氨酸)[P(LA-co-Ala)],并用特性粘数、IR、1H-NMR等手段对目标产物进行了表征。研究催化剂的种类和用量、聚合温度、聚合时间等对P(LA-co-Ala)合成的影响,得到最佳实验条件为:分步脱水后,以SnO为催化剂(质量分数为0.7%),170℃、70Pa下反应8h,P(LA-co-Ala)的特性粘数为0.7888 dL/g。     

Catalytic synthesis of sulfur and phosphorus compounds via atom-economic reactions

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An efficient one-pot synthesis of pyrrolines and tetrahydropyridines from their chloro-precursors via in situ aza-Wittig reaction

A simple and efficient method for synthesizing pyrrolines and tetrahydropyridines via an intramolecular aza-Wittig reaction has been achieved by microwave irradiation of the corresponding chloro-alkane derivatives in the presence of tertiary phosphite and sodium azide. The in situ formation of the alkyl azides makes this a facile and safe method for aza-Wittig reactions.     

An efficient synthesis of 2-Aminoethylidene-1,1-Bisphosphonates derivatives via Michael addition reaction

A facile, rapid and cheap synthetic strategy towards a wide range of novel 2-aminoethylidene-1,1-bisphosphonate derivatives was developed through the Michael addition reaction of various aromatic amines, aromatic amides as well as nucleoside analogues with tetraethyl ethenylidene-1,1-bisphosphonate. All the newly obtained compounds were characterized by ¹H, ³¹P, ¹³C NMR spectroscopy, IR and HR MS.     

Environment friendly organic synthesis using bismuth compounds. An efficient method for carbonyl-ene reactions catalyzed by bismuth triflate

Bismuth triflate (0.1 mol %) is a highly efficient catalyst for the cyclization of citronellal 1, a reaction that yields a ratio of 80:20 of isopulegol 2 and neoisopulegol 3. This methodology has also been extended to the synthesis of substituted piperidines. The bismuth triflate catalyzed ene reaction of aldehyde 4 gives a 70:30 mixture of piperidines 5 and 6. The advantages of these methods include the use of a highly efficient catalyst that is relatively nontoxic, cheap and easy to handle.     

An expedient synthesis of poly-substituted 1-arylisoquinolines from δ-ketonitriles via indium-mediated Barbier reaction protocol

We developed an efficient synthetic strategy of poly-substituted 1-arylisoquinolines via an indium-mediated Barbier type allylation from δ-ketonitriles. Initial attack of allylindium species occurred at the nitrile group selectively to form the enamine intermediate, which reacted with the ketone group intramolecularly to furnish the isoquinolines.     

An efficient catalytic protocol for the Pauson-Khand reaction

New experimental conditions have been developed for an efficient catalytic Pauson-Khand reaction. These are based on the use of a mixture of molecular sieves and tert-butanol as inducers of the process. This mixture, with the appearance of a paste, is able to adsorb CO, thus improving the conversion and making it possible to effect the reactions in the absence of a CO atmosphere. The protocol is applied to known and unknown substrates and compared to previously described conditions, showing good results with intra- and intermolecular examples.     

An efficient one-pot synthesis of thiophene-fused pyrido[3,2-a]azulenes via Gewald reaction

A simple and efficient procedure was developed for the synthesis of 11H(2H)-4-oxothiophene[3',4':6,5]pyrido[3,2-a]azulene-10-carboxylates(3) in moderate to good yields via the Gewald reaction of ethyl 1-cyanoacetyl-2-methoxyazulene-3-carboxylate(1) with carbonyl compounds(2) and elemental sulfur utilizing imidazole as catalyst.This reaction provides a new procedure for synthesis of pyridinone-fused azulenes.     

An efficient one-pot reaction for the synthesis of pyrazolones bearing a phenothiazine unit

A simple one-pot approach for the synthesis of new pyrazolones containing a phenothiazine unit is reported. Compound 4b was evaluated for its antiproliferative activity on a NCI-60 cancer cell line panel and exhibited selective cytostatic activity toward CCRF-CEM, HL-60(TB), K-562, MOLT-4, and RPMI-8226 leukemia cell lines.     

An efficient synthesis of 3,4-dihydropyridone via a tandem olefin isomerization–ring-closing metathesis reaction

Novel 3,4-dihydropyridones were efficiently prepared via a tandem olefin isomerization–ring-closing metathesis reaction catalyzed by the second-generation Grubbs catalyst. The products were further functionalized at the 5-position, providing an interesting structural motif to be evaluated in medicinal chemistry.     

Poly(4-vinylpyridinium)hydrogen sulfate: An efficient heterogeneous catalyst for the one-pot synthesis of polyhydroquinolines via unsymmetrical Hantzsch reaction in aqueous medium

A facile and highly efficient protocol for the synthesis of polyhydroquinolines via Hantzsch multicomponent condensation of dimedone, aryl/heteryl aldehydes, ethylacetoacetate and ammonium acetate utilizing poly(4-vinylpyridinium)hydrogen sulfate as a catalyst in aqueous medium has been described. The method offers several advantages such as high yield, short reaction time, simple workup, easy separation of the catalyst and its reusability.