关键词： asymmetric synthesis   trifluoromethyl   amine   aldehyde  

摘要： The first asymmetric synthesis of the beta-trifluoromethylated beta-amino aldehyde, which is one of the most promising precursors for the synthesis of trifluoromethylated bioactive compounds, is described. (c) 2005 Elsevier B.V. All rights reserved.

关键词： Ethers   Reagents   Aldehydes   Hydrolysis   Stereoselectivity  

摘要： Hydroboration of ethoxy acetylene, transmetalation to zinc, and addition to aldehydes in the presence of a chiral amino alcohol ligand (MIB) affords hydroxy enol ethers with high ee. The resultant enantiomerically enriched hydroxy enol ethers were converted to protected hydroxy aldehydes, a useful synthetic building block for the construction of a variety of polyoxygenated natural products. In addition, diastereoselective formation of syn- and anti-1,3-diols was studied.

关键词： Hydrocarbons   Anions   Aromatic compounds   Molecular structure   Pharmaceuticals  

摘要： Asymmetric total syntheses of the dibenzocyclooctadiene lignans interiotherin A and angeloylgomisin R are reported. The syntheses were based on an atropdiastereoselective, copper-promoted biaryl coupling reaction, a diastereoselective hydroboration/Suzuki-Miyaura coupling reaction sequence, and an asymmetric boron-mediated tiglylation of an aryl aldehyde precursor.

关键词： PHOSPHINE   HYDROXY acids   PHOSPHORUS compounds   ACIDS   CARBOXYLIC acids   CHEMISTRY  

摘要： The anti selective hydrogenation of alpha-amino-beta-keto esters via dynamic kinetic resolution was achieved for the first time by using the iridium-MeOBIPHEP catalyst in asymmetric synthesis of anti aromatic beta-hydroxy-alpha-amino acid esters with excellent diastereo- and enantioslectivities. Acetic acid as a solvent and sodium acetate as an additive affected dramatically the yield and the enantioselectivity, respectively. The product anti aromatic beta-hydroxy-alpha-amino acid esters are useful for synthesis of pharmaceuticals and natural products.

关键词： alkylation   chiral auxiliaries   lactams   peptidomimetics  

摘要： 2-Substituted 1,4-benzodiazepine-2-one compounds (9-12) were obtained by a highly diastereoselective alkylation of a seven-membered ring benzolactam (8) in the presence of (R)phenylglycinol as a chiral inductor. The corresponding acid derivative (16) afforded a conformationally constrained structure suitable for preparing peptidomimetic analogues useful as a novel molecular scaffold. After cleavage of the chiral appendage this approach might also lead efficiently to enantiomerically pure 2-substituted benzodiazepines (15). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

关键词： ENANTIOPURE CYCLIC NITRONE   VINYLOGOUS MANNICH REACTIONS   ENYNE METATHESISREACTION   PARVIFLORA WRIGHT CH   CYCLOADDITION REACTIONS   1   3-DIPOLAR CYCLOADDITIONS   CRYSTAL-STRUCTURE   N-OXIDES   ORGANOMETALLIC REAGENTS   MOLECULAR-STRUCTURE  

摘要： A general strategy for the construction of the 1-azabicyclo[5.3.0]decane core of Stemona alkaloids is developed. Our diversity-oriented approach exploits 1,3-dipolar cycloaddition of five-membered cyclic nitrones to C-6 olefins, followed by N-O reductive cleavage and azepine closure. The use of various enantiopure pyrroline N-oxides allows for a practical, stereoselective preparation of several putative precursors of different Stemona alkaloids.

关键词： AXIALLY DISSYMMETRIC MOLECULES   ALUMINUM-HYDRIDE REAGENTS   CARBON BONDFORMATION   TERT-BUTYL ESTERS   ENANTIOSELECTIVE REDUCTION   PHOSPHODIESTERASE-4 INHIBITOR   CONJUGATEADDITION   SELECTIVE HYDROGENATION   ARYLLITHIUM REAGENTS   AROMATIC KETONES  

摘要： A practical, chromatography-free catalytic asymmetric synthesis of a potent and selective PDE4 inhibitor (L-869,298, 1) is described. Catalytic asymmetric hydrogenation of thiazole ketone 5a afforded the corresponding alcohol 3b in excellent enantioselectivity (up to 99.4% ee). Activation of alcohol 3b via formation of the corresponding p-toluenesulfonate followed by an unprecedented displacement with the lithium enolate of ethyl 3-pyridylacetate N-oxide 4a generated the required chiral trisubstituted methane. The displacement reaction proceeded with inversion of configuration and without loss of optical purity. Conversion of esters 2b to 1 was accomplished via a one-pot deprotection, saponification, and decarboxylation sequence in excellent overall yield.

关键词： Reagents   Oxides   Anions   Stereoselectivity   Enantioselective synthesis  

摘要： [GRAPHICS] A general process for the efficient synthesis of sulfinyl transfer agents has been developed using cinchona alkaloids quinine and quinidine as chiral auxiliaries. The importance of these new and unique sulfinyl transfer agents is exemplified by the expedient synthesis of several sulfoxides in excellent enantiopurities and high yields.

关键词： METHOXY-N-METHYLAMIDES   DIASTEREOSELECTIVE ALKYLATION   1   2   3   6-TETRAHYDRO-2-PYRAZINONE STRUCTURE   STEREOCONTROLLED SYNTHESIS   EFFICIENT SYNTHESIS   ORGANIC-SYNTHESIS   ALANINE TEMPLATE   WEINREB AMIDES   SOLID-PHASE   SIDE-CHAIN  

摘要： Highly enantioselective alkylation of protected glycine diphenylmethyl (Dpm) amide 1 and Weinreb amide 10 has been realized under phase-transfer conditions by the successful utilization of designer chiral quaternary ammonium salts of type 4 as catalyst. Particularly, remarkable reactivity of the chiral ammonium enolate derived from 1b and 4c allowed the reaction with less reactive simple secondary alkyl halides with high efficiency and enantioselectivity. An additional unique feature of this chiral ammonium enolate is its ability to recognize the chirality of beta-branched primary alkyl halides, which provides impressive levels of kinetic resolution and double stereodifferentiation during the alkylation, allowing for two alpha- and gamma-stereocenters to be controlled. Combined with the subsequent reduction using LiAlH4 in cyclopentyl methyl ether (CPME), this system offers a facile access to structurally diverse optically active vicinal diamines. Furthermore, the optically active a-amino acid Weinreb amide 11 can be efficiently converted to the corresponding amino ketone by a simple treatment with Grignard reagents. In addition, reduction and alkylation of the optically active alpha-amino ketone into both syn and anti alpha-amino alcohols with almost complete relative and absolute stereochemical control have been achieved. With (S,S)- and (R,R)-4 in hand, the present approach renders both enantionners of alpha-amino amides including Weinreb amides readily available with enormous structural variation and also establishes a general and practical route to vicinal diamines, a-amino ketones, and a-amino alcohols with the desired stereochemistry.

关键词： 不对称催化反应   应用研究进展   螺环   手性   配体   不对称合成   研究领域  

摘要： 手性螺环配体的合成及其在不对称催化反应中的应用是不对称合成和催化研究中重要的研究领域之一,一些手性螺环配体被合成出来并成功地应用于不对称催化反应中.综述了近十年来手性螺环配体的合成及在不对称催化反应中的应用研究进展.