A new synthetic approach to 7-hydroxynitidine

Benzo[c]phenanthridine alkaloid, 7-hydroxynitidine, was synthesized from readily available 2-benzyloxy-6-bromo-3,4-dimethoxybenzaldehyde 5 and napthylamine 6 using reductive amination followed by radical cyclization in eight steps. This method is highly efficient and better way to synthesize fully aromatized benzo[c]phenanthridine compounds.     

1-甲基-4-硝基-5-氯咪唑的合成新工艺研究

1-甲基-4-硝基-5-氯咪唑是合成免疫抑制剂硫唑嘌呤(Azathioprine)的中间体.硫唑嘌呤可抑制人体内淋巴细胞,减少狼疮病人的免疫复合物在肾脏的沉积,抑制局部炎症.同时用于治疗类风湿关节炎、各种血管炎、多发性肌炎皮肌炎及系统性红斑狼疮等.     

A new facile approach to N-alkylpyrroles from direct redox reaction of 4-hydroxy-l-proline with aldehydes

An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-L-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.     

A new approach to the one-pot synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles from N-tributylstannyltetrazoles

A new approach to the synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles was developed.     

Regioselective and Stereoselective Synthesis of the 3-Aryl-4- phosphoryl-1, 2, 4-triazoline-5-ones

Regioselective cyclization of 1-acylthiosemicarbazides has been shown to be an excellent method for the synthesis of triazoles, thiadiazoles and oxadiazoles, with a variety of potential biological activities1-6 and utilities as pharmacological properties7…     

3-正丙基-4-氨基-5-酰胺基-1-甲基吡唑的合成

以2－戊酮为起始原料，经Claisen缩合、环化、甲基化、皂化、硝化、酰胺化和还原反应，制得目标化合物。总收率比文献报道值提高一倍，达46．8％。     

Highly stereoselective Friedel-Crafts type cyclization. Facile access to enantiopure 1,4-dihydro-4-phenyl isoquinolinones

The present report describes a stereoselective synthesis of 1,4-dihydro-4-phenyl isoquinolinones 5 based on a stereoselective Friedel-Crafts type cyclization. Cyclization precursors 1 were prepared in two steps, from the readily available (S)-mandelic acid, in 60-80% overall yield. The stereoselective electrophilic cyclization was accomplished in 20-86% yield and with 20-97% ee. In the course of this work, the presence of the amide carbonyl was found to be particularly important to guarantee a stereospecific process during the electrophilic aromatic substitution.     

2,4,4-trisubstituted 5-amino-4h-imidazoles. A new synthetic approach and reactivity

The scope and limitations of the reaction between imidates and α,α-disubstituted α-aminoacetonitriles to give 5-amino-4H-imidazoles are studied. The reactivity of compounds 1a-b has been explored.     

A new synthetic approach to phosphatidylethanolamine

A new synthetic method for phosphatidylethanolamine head group was developed via ring-opening of cyclic dioxaphospholane 2 with sodium azide and subsequent hydrogenation.The advantage of this strategy included short reaction steps,readily available materials and good yields.     

A new approach to 1-alkyl-1,3-dihydro-2H-benzimidazol-2-ones

A new procedure for preparing 1-alkyl-1,3-dihydro-2H-benzimidazol-2-ones fromo-nitroanilines by successive ethoxycarbonylation, catalytic hydrogenation and thermal cyclization under neutral conditions is described.

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Eine neue Synthese von 1-Alkyl-1,3-dihydro-2H-benzimidazol-2-onen

Zusammenfassung Eine neue Methode zur Darstellung von 1-Alkyl-1,3-dihydro-2H-benzimidazol-2-onen auso-Nitroanilinen durch Ethoxycarbonylierung, katalytische Hydrierung und thermische Cyclisierung wird beschrieben.

     

A new synthetic approach to benzomorphans

A new approach to the synthesis of benzomorphan derivatives is exemplified by the obtention of 3,6-dimethyl-benzomorphan from the readily available 1-methyl-2,3-benzobicyclo-[3,2,l]octane-4,6-dione.     

A practical approach to new (5Z) 2-alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one derivatives

A practical protocol for the preparation of (5Z)-2-alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one derivatives is reported. The new compounds were obtained in good yield and stereoselectivity in two steps, namely a solvent-free Knoevenagel condensation under microwave irradiation, followed by an S-alkylation reaction with various halogenoalkanes.     

5-Aminocyclopentadienes by intramolecular addition of enolether to aminoallene functionalities

3-(1-Alkoxyvinyl)-1-aminoallenes 6 were generated by conjugate addition of acyclic and cyclic (1-alkoxyvinyl)cuprates with the semicyclic propyne iminium salt 4. They isomerized smoothly into spiroannellated cyclopentadienes 7 through a 1,5-cyclization that in some cases occurred already at ≤20°C. (1-Methoxyallenyl)cuprates reacted with salt 4 in a 2:1 ratio to give the 5,5-dimethoxy-4-methylenepentalene-1-spiro-2′-dihydroindole derivative 10. The thermal isomerization of morpholinoallene 12 into cyclopentadiene 13 indicates that the novel 1,5-cyclization can be extended to other 3-(1-alkoxyvinyl)-1-aminoallenes as well.     

Aziridination of 3-methyl-4-nitro-5-styrylisoxazoles

Herein we describe the preparation of a novel class of isoxazolyl aziridines. The products were obtained exclusively as cis diastereoisomers.     

New synthetic approach to [1]benzopyrano[4,3-b]pyridin-5-one derivatives

A new synthesis of [1]benzopyrano[4,3-b]pyridin-5-ones 4 was developed starting from 3-formyl-coumarin N-functionalized amidines 3. The reaction is based likely on the intramolecular cyclocondensation of the C-α amidinic carbanion in basic medium on the formyl group.     

A new synthetic approach to phenothiazine-2-amines

Elaboration of a Buchwald-Hartwig protocol for the introduction of amino functions to position 2 of the phenothiazine ring system has opened a new access to various N-alkyl and N-dienyl phenothiazines bearing secondary amines, tertiary amines, and amide moieties. Hydrolysis of the amido derivatives gave unsubstituted phenothiazine-2-amines. This protocol provides an easy access to phenothiazine-2-amines starting from the commercially available starting compounds.     

An entry to 7-amino- and to 2-ethoxycarbonyl-5-dethia-5-oxa-cephams from 1,3-alkylidene-l-erythritol

The alkoxyallene derived from 1,3-benzylidene-l-erythritol when treated with chlorosulfonyl isocyanate provided diastereomeric β-lactams with moderate stereoselectivity. After the intramolecular alkylation of the nitrogen atom, these afforded compounds having oxacepham skeletons. The exo-isopropylidene group enabled the introduction of a variety of substituents to the C-7 carbon atom of the cepham, whereas removal of the benzylidene protection followed by the oxidation of 3-OH to the ketone allowed carboxylation of the C-2 carbon atom.