关键词： ALPHA-AMINO-ACIDS   STEREOSELECTIVE-SYNTHESIS   MICROBIAL METABOLITE   NEUROBLASTOMA-CELLS   HYDROXY ACIDS   DERIVATIVES   ESTERS   VIRANTMYCIN   LACTACYSTIN   METHIONINE  

摘要： A two-step protocol for the asymmetric synthesis of protected quaternary (E)-vinylglycines from simple aldehydes is reported. The key step is a regiocontrolled deconjugative asymmetric alkylation of dehydroamino acids, giving the targets as single geometric isomers with high diastereoselectivity (92-96% de). The products can be converted to valuable quaternary beta-amino alcohols by chemoselective reduction.

关键词： MICHAEL ADDITION-REACTIONS   NUCLEOPHILIC GLYCINE EQUIVALENTS   SUBSTITUTEDPYROGLUTAMIC ACIDS   NECROSIS-FACTOR-ALPHA   FACE DIASTEREOSELECTIVITY   NEW-GENERATION   AMINO-ACIDS   ENANTIOMERS   DERIVATIVES   STEREOSELECTIVITY  

摘要： The preparation of new thalidomide derivatives 4-methyl-(3S,4R)-3a and 4-phenyl-(3S, 4S)-3b starting from pyroglutamic acids (2R, 3R)-7a and (2R, 3S)-7b, possessing an inappropriate stereochemistry, was successfully realized due to stereochemically complete epimerization at the alpha-stereogenic center upon formation of the corresponding N-phthaloyl anhydrides 9a,b. The demonstrated conformational stability of these new thalidomide derivatives provides solid experimental evidence for practical feasibility of the approach described here to overcome the inherent problem of configurational instability of thalidomide by introducing an alkyl or aryl group in the C4 position.

关键词： sensitivity analysis   asymmetric damped systems   eigenvalue sensitivities   eigenvector sensitivities   rotor dynamic model  

摘要： In general, the derivative of an eigenvector of a vibrating symmetric system is the solution of a singular problem. Further complications are encountered in dealing with asymmetric damped systems for which the left and right eigenvectors, and their derivatives become distinct and complex. Several approaches have been proposed to overcome this singularity such as Nelson's method and the modal method. In the present work, a new approach is presented for calculating simultaneously the derivatives of the eigenvalues and their associated derivatives of the left and right eigenvectors for asymmetric damped systems. With the proposed method, the exact eigenderivatives can be obtained by solving a first-order linear algebraic system of equations. The method is applied on a 104 DOF ventilator-rotor system, which is used as an example of an asymmetric damped system with distinct eigenvalues. The diameter of the shaft has been chosen as the design parameter. The comparison of the computational time shows that the proposed method is more efficient than both Nelson's approach and the modal method. Copyright (c) 2006 John Wiley & Sons, Ltd.

关键词： 手性α-氨基酸   不对称合成   综述  

摘要： 按合成方法综述了手性α-氨基酸的研究进展。简要介绍了手性拆分、L-氨基酸的高同系化、不对称烷基化、亚胺的不对称烷基化、脱氢氨基酸的不对称氢化等各种合成方法。对手性α-氨基酸合成的今后发展方向做了讨论。

关键词： 生物催化   不对称还原   不对称合成   羰基还原   手性醇   前手性酮  

摘要： 利用活性微生物细胞催化羰基不对称还原成为手性醇合成的重要方法。虽然当前已经筛选出许多立体选择性很高的微生物和反应过程,但这类反应能实际应用的还很少,主要是因为产业化方面的研究不够。本文从此出发,结合作者近几年的研究工作对当前活性微生物细胞催化羰基不对称还原相关工程方面的研究进行了详细的介绍和论述。分析了利用活性细胞催化时空产率低的原因,对国内外研究者针对这些原因为提高时空产率所进行的各种研究和提出的方法分别进行了归纳和分析。

关键词： 苯磺酸贝他斯汀   抗过敏药   不对称合成  

摘要： 用(S)-[Ru(BINAP)Cl2]2(NEt3)作催化剂,不对称氢化还原(4-氯苯基)-(吡啶-2-基)-甲酮得到(S)-(+)-(4-氯苯基)-(吡啶-2-基)-甲醇,与4-(4-溴哌啶-1-基)丁酸乙酯缩合,再经水解、成盐得到抗过敏药苯磺酸贝他斯汀,总收率57%。

关键词： fluorine   enolate   decarboxylation   palladium  

摘要： This manuscript details the development of an asymmetric, palladium-catalyzed, decarboxylative coupling of fluoroenolates with allyl electrophiles.

关键词： enantiopure beta-amino alcohols and beta-diamines   chiral ligands   alkylation of enolates   chiral oxazolidinones   determination of enantiomeric purity  

摘要： This Account describes convenient procedures for the preparation of several enantiopure beta-amino alcohols and beta-diamines, which have proved to be efficient ligands in relevant stereoselective reactions such as alkylation of enolates and hydrogenation of carbonyl compounds. Furthermore, the title compounds are useful precursors of various chiral oxazolidinones, oxazinones, phosphonamides, etc., which allow the enantioselective formation of a wide variety of chiral derivatives, including alcohols, aldol condensation products, aminophosphonic acids, sulfoxides, and others, as well as the development of derivatizing reagents for the determination of enantiomeric purity in chiral alcohols and chiral amines. 1 Introduction 2 Chiral Cyclic 1,2-Amino Alcohols Derived from Cyclohexene Oxide 2.1 Synthesis of Enantiopure Cyclic 1,2-Amino Alcohols Derived from Cyclohexene Oxide 2.2 Enantioselective Addition of Diethylzinc to Aldehydes in the Presence of Chiral Cyclic 1,2-Amino Alcohols as Ligands 2.3 Synthesis of Chiral 1,4-Oxazin-2-ones and their Diastereo-selective alpha-Alkylation 3 Synthesis of cis- and trans-Hexahydrobenzoxazolidin-2-ones and their Application as Chiral Auxiliaries in Asymmetric Synthesis 3.1 Diastereoselective alpha-Alkylation 3.2 Diastereoselective Aldol Reaction 3.3 Regio- and Diastereoselective C-Acylation 3.4 Stereospecific Chiral Sulfinyl Transfer Agents 3.5 Stereoselective Michael Addition 3.6 Diastereoselective Azidation 4 Chiral Cyclic 1,2-Diamines Derived from Cyclohexene Oxide 4.1 Synthesis of Enantiopure Cyclic 1,2-Diamines 4.2 Application of Phosphorylated Derivatives of Enantiopure 1,2-Diamines as Chiral Derivatizing Agents 4.3 Enantioselective Reduction of Acetophenone in the Presence of Enantiopure 1,2-Diamines 4.4 Synthesis of Sulfonamide Ligands and their Application in the Enantioselective Alkylation, Vinylation and Allylation of Ketones 4.5 Diastereoselective Addition of Phosphorylated Derivatives to Aldehydes.

关键词： CHELATE COMPOUNDS   SPIN EQUILIBRIA   ACID   SUSCEPTIBILITY   LIGAND  

摘要： A C-2 hexadentate, in which two pyridine-2-aldehyde 2'-pyridylhydrazone ( PAPHY) groups are linked to a chiral auxiliary derived from (R,R)-tartaric acid, (R,R)-1, reacts with iron(II) benzenesulfonate to give the two-bladed propeller, octahedral complex (P-Fe)-[Fe{(R,R)-1}](PhSO3)(2) with complete diastereoselectivity, as determined by H-1 NMR spectroscopy and X-ray crystallography. Saponification of the ester linkages and deprotonation of the hydrazone-NH groups in the configurationally pure diastereomer affords the complex (P-Fe)-[Fe(5-HOCH(2)PAPY)(2)] with 85% retention of configuration at the iron stereocenter, as determined by reprotonation of the neutral complex with enantiomerically pure (aR)-binaphthyl phosphoric acid and analysis of the H-1 NMR spectrum of the mixture of diastereomeric salts produced. This is the first asymmetric synthesis of a two-bladed propeller, octahedral metal complex by the classical organic methodology of chiral auxiliary-directed, asymmetric synthesis.

关键词： 氮杂糖   哌啶   羟甲基化   手性砌块   L-deoxygulojirimycin  

摘要： 报道一种合成天然氮杂糖L-deoxygulojirimycin关键中间体及全保护L-gulono-1,5-lactam的方法.其关键反应之一为二碘化钐(SmI2)促进下对硅基保护的3-羟基戊二酰亚胺10的C-2位的区域和立体选择性不对称羟甲基化,区域选择性为80 20,立体选择性为93 7;另一关键反应为采用OsO4-NMO体系对18进行不对称双羟基化反应,立体选择性单一,并通过NOE确定产物的立体化学.