A novel and facile synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-1H-indole-4(5H)-ones via a one-pot multi-component reaction

A simple and efficient synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-1H-indole-4(5H)-ones was achieved via a one-pot multi-component reaction of cyclohexyl isocyanide, an aldehyde, a 1,3-dicarbonyl compound, and ammonium acetate in the presence of a catalytic amount of KHSO₄ in acetonitrile.     

Synthesis of (9E)-isoambrettolide, a macrocyclic musk compound, using the effective lactonization promoted by symmetric benzoic anhydrides with basic catalysts

Two alternative methods for the synthesis of (9E)-isoambrettolide are established via the rapid lactonization of the free threo-aleuritic acid or its protected seco-acid using substituted benzoic anhydrides with basic catalysts. The most efficient lactonization of the threo-aleuritic acid is performed using 2-methyl-6-nitrobenzoic anhydride (MNBA) with a catalytic amount of 4-dimethylaminopyridine N-oxide (DMAPO).     

Facile synthesis of N-(benzyl, methyl)-lysine as a building block for site-specifically lysine monomethylated peptides

Facile, mild and efficient one-pot preparation of N^α-Fmoc-N^ε-(benzyl, methyl)-lysine, a building block for monomethylated peptide synthesis, was described. This building block was proved to be efficient for the synthesis of site-specifically monomethylated peptide. Benzyl group, which was incorporated by reductive benzylation and removed via catalytic hydrogenolysis, served as an excellent protecting group.     

Disproportionation reaction of diarylmethylisopropyl ethers: a versatile access to diarylmethanes from diarylcarbinols speeded up by the use of microwave irradiation

An efficient synthesis of diarylmethanes under classical thermal conditions and under microwave heating is described from diarylcarbinols via a new disproportionation reaction. The key step involves a selective hydride transfer of isopropyl ether intermediates. Mild reaction conditions i.e., catalytic CBr₄ or TfOH in i-PrOH and good yields render this method useful and competitive to the conventional approaches relying on application of external reducing agents.     

Studying the reactivity of (phthalazin-1(2H)-on-2-yl)methyl trichloroacetimidate towards different C- and O-nucleophiles

A simple and efficient synthesis of phthalazin-1(2H)-one 2-substituted derivatives is achieved in very good yields via reaction of a phthalazinone-trichloroacetimidate with various C- and O-nucleophiles such as aromatic, heteroaromatic and olefinic reagents, sugars and cholesterol in CH₂Cl₂ in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf).     

A concise enantioselective synthesis of l-(−)-733,061 and (2S,3S)-methyl 3-aminopiperidine-2-carboxylate using catalytic enantioselective aza-Henry reaction as key step

An efficient enantioselective synthesis of l-(−)-733,061 and (2S,3S)-methyl 3-aminopiperidine-2-carboxylate is accomplished by means of catalytic enantioselective aza-Henry reaction. A key feature of this protocol is organocatalysis as genesis of chirality to ensure high degree of distereo- and enantiocontrol.     

CuFe2O4 nanoparticles: a magnetically recoverable and reusable catalyst for the synthesis of 5-substituted 1H-tetrazoles

An efficient and economical protocol for the synthesis of 5-substituted 1H-tetrazoles from various nitriles and sodium azide is described using magnetically recoverable and reusable CuFe₂O₄ nanoparticles. A wide variety of aryl nitriles underwent [2+3] cycloaddition under mild reaction conditions to afford tetrazoles in good to excellent yields. The catalyst was magnetically separated and reused five times without significant loss of catalytic activity.     

Synthesis of 1,2,4,5-tetrasubstituted imidazoles using silica-bonded propylpiperazine N-sulfamic acid as a recyclable solid acid catalyst

A simple and efficient procedure for the preparation of silica-bonded propylpiperazine-N-sulfamic acid (SBPPSA) by the reaction of 3-piperazine-N-propylsilica (3-PNPS) and chlorosulfonic acid in chloroform is described. Silica-bonded propylpiperazine-N-sulfamic acid is employed as a recyclable catalyst for the synthesis of highly substituted imidazoles from the reaction of benzil, aromatic aldehydes, ammonium acetate and amines under solvent-free conditions. The heterogeneous catalyst was recycled for five runs upon the reaction of benzil, 4-methylbenzaldehyde, benzylamine, and ammonium acetate without losing its catalytic activity.     

N,N-Dichlorobis(2,4,6-trichlorophenyl)urea (CC-2) as a new reagent for the synthesis of pyrimidone and pyrimidine derivatives via Biginelli reaction

A simple and efficient method for the synthesis of 3,4-dihydropyrimidin-2-(1H)one and benzo[4,5]imidazo/thioazo[1,2-a]pyrimidine derivatives has been described using N,N′-dichlorobis(2,4,6-trichlorophenyl)urea (CC-2) as a new reagent. This method is found to be efficient and convenient for the synthesis of pyrimidone and pyrimidine derivatives.     

Enantioselective synthesis of (2S,3′R,7′Z)-N-(3′-hydroxy-7′-tetradecenoyl)-homoserine lactone

A concise enantioselective total synthesis of (2S,3′R,7′Z)-N-(3′-hydroxy-7′-tetradecenoyl)-homoserine lactone is described. Key feature of this protocol is a catalytic asymmetric hydrogenation and a prophenol-zinc-catalyzed diazo addition to imine reaction as genesis of chirality. Moreover, flexibility is built in the synthesis to generate enantioenriched analogs using catalytic amount of enantioenriched C₂-symmetric ligands.     

Microwave-assisted cleavage of Weinreb amide for carboxylate protection in the synthesis of a (R)-3-hydroxyalkanoic acid

A versatile route for the modular synthesis of (R)-3-hydroxyalkanoic acids, constituents of the naturally biodegradable poly(3-hydroxyalkanoate) polymers, and its application to the synthesis of (R)-3-hydroxydecanoic acid is described. Key steps include a microwave-assisted catalytic transfer hydrogenation and a facile microwave-assisted hydrolysis of an N-methoxy-N-methyl (Weinreb) amide, which enhances the practicality of this protecting group for carboxylic acids.     

Indium triflate-catalyzed one-pot synthesis of 1-substituted-1H-1,2,3,4-tetrazoles under solvent-free conditions

A simple, efficient, and general method has been developed for the synthesis of 1-substituted-1H-1,2,3,4-tetrazoles via a three-component condensation of amine, trimethyl orthoformate, and sodium azide in presence of a catalytic amount of indium triflate under solvent-free conditions. The reaction proceeds smoothly to generate the corresponding 1-substituted tetrazoles in moderate to excellent yields under heating.     

Synthesis of complex alkoxyamines using a polymer-supported N-hydroxyphthalimide

The synthesis of a polymer-supported N-hydroxyphthalimide is described. The polystyrene-bound N-hydroxyphthalimide resin 1 has been used to prepare complex alkoxyamines exhibiting both stereochemical and positional diversity. Methods for efficient condensation of complex alkoxyamines with aldehydes and ketones are also outlined.     

An efficient catalytic method for the synthesis of 2,7-dialkyl-2,3a,5a,7,8a,10a-hexaazaperhydropyrenes

An efficient method for the synthesis of 2,7-dialkyl-2,3a,5a,7,8a,10a-hexaazaperhydropyrenes in high yields (up to 95%) via the intermolecular cyclization of 1,4,5,8-tetraazadecalin with N,N-bis(methoxymethyl)-N-alkylamines in the presence of SmCl₃·6H₂O as the catalyst has been developed.     

Efficient trans-acetoacylation mediated by ytterbium(III) triflate as a catalyst under solvent-free condition

A simple and efficient trans-acetoacylation method for the synthesis of β-keto ester derivatives has been described using ytterbium(III) triflate as a new catalyst under solvent-free condition. This method was found to be efficient and convenient for the synthesis of a wide variety of β-keto ester derivatives.     

Oxidative cyclization of a seco-cladiellane diterpenoid

A short and efficient synthesis of a diterpenoid with a 1,2-seco-cladiellane carbon skeleton is described, starting from geraniol and carvone. One-step oxidative cyclization with a RuO₂/NaIO₄ system leads to two diastereomeric, bicyclic triols, which contain six stereogenic centers and will be helpful in the synthesis of eleutherobin. The stereochemical outcome of this cyclization has been determined by X-ray analysis.     

Concise total synthesis of flavone C-glycoside having potent anti-inflammatory activity

The total synthesis of anti-inflammatory active flavone C-glycoside isolated from oolong tea extract is achieved. Introducing a C-glucosyl moiety to an aryl system and constructing a fused tetracyclic ring characteristic to this natural product were conducted based on the O-to-C rearrangement of sugar moiety and the successive intramolecular Mitsunobu reaction, respectively. This concise and efficient synthetic pathway is applicable to the large-scale synthesis of target flavone and for constructing a large library of related compounds.     

Stereoselective synthesis of C1-C5 and C4-C5 linked deoxy disaccharides via a ring closing metathesis protocol

The stereoselective synthesis of C-C linked deoxy disaccharides by a short and efficient route is described. An RCM strategy was adopted for the assembly of the required ring skeleton on the sugar unit, while OsO₄ was used to introduce the vic-diol unit.     

Nickel-catalyzed, base-mediated amination/hydroamination reaction sequence for a modular synthesis of indoles

A catalytic system consisting of [Ni(cod)₂] and ligand dppf enabled an efficient synthesis of differently substituted indoles through a modular reaction sequence, which consists of intermolecular aminations and intramolecular hydroaminations with ortho-alkynylhaloarenes.     

Synthesis of an indole containing KDR kinase inhibitor by tandem Sonogashira coupling-5-endo-dig-cyclization as a key step

An efficient synthesis of the potent KDR kinase inhibitor 3-[5-[[4-(methylsulfonyl)-1-piperazinyl]methyl]-1H-indol-2-yl]quinoline-2-(1H)-one using a Sonogashira coupling-5-endo-dig-cyclization strategy is described.