关键词： .acid derivatives   asymmetric synthesis   sultam   derivatives of glyoxylic   glyoxyloyl bornane  

摘要： Synthesis of chiral derivatives of glyoxylic acid with special emphasis on N-glyoxyloyl-(2R)-bornane-10,2-sultam is presented. Investigation of glyoxylic acid chiral derivatives in various stereocontrolled organic syntheses showed their excellent ability to provide products of high optical purity. Application of our methodology to the synthesis of natural products and their analogs is presented.

关键词： 酶抑制剂/化学合成   酶抑制剂/化学   指示剂和试剂   内酯类/化学合成   内酯类/化学   模型   分子   分子构象   链霉菌属  

摘要： [GRAPHICS] A stereoselective synthesis of (-)-tetrahydrolipstatin is described. The synthesis involves an asymmetric ester derived titanium enolate anti-aldol reaction, a nitro aldol reaction to append the C2' C-11 side chain, and a diastereoselective reduction of a beta-hydroxy ketone to an anti-1,3-diol functionality followed by its elaboration to (-)-tetrahydrolipstatin.

关键词： X-rays   Cyclization   Chemical structure   Organic compounds   Molecular structure  

摘要： [GRAPHICS] Here, we report a novel synthesis of a monosubstituted, enantio and diastereomerically enriched transcyclononadienol. The reaction consists of an enantioselective (-)-sparteine-mediated allylic lithiation of an achiral 7-chlorononadienyl carbamate and a subsequent stereospecific intramolecular allyllithium-allyl chloride coupling. The stereochemical course of the cyclization has been determined, and the high configurative stability of the chiral nine membered carbocycle has been investigated by kinetic measurements and rationalized by computational calculations.

关键词： 联苯化合物/化学合成   联苯化合物/化学   指示剂和试剂   模型   分子   分子构象   苯乙酸酯类/化学合成   苯乙酸酯类/化学   万古霉素/化学合成   万古霉素/化学  

摘要： [GRAPHICS] Synthesis of fully protected actinoidic acid derivative 3 and selectively protected biaryl bisamino acid 4, intermediates for vancomycin total synthesis, are reported.

关键词： 手性试剂   L-焦谷氨酸酯   不对称合成   反应温度   后处理方法   化学产率   酯化   高温热环合  

摘要： 以价廉易得的L -谷氨酸为原料 ,经酯化、高温热环合得L -焦谷氨酸酯 ,并对已有文献的后处理方法进行了改进 ,化学产率高于文献值 ,且产物不易消旋 .

关键词： 羟腈酶   光活性羟腈化合物   基因工程   手性药物   不对称合成  

摘要： 羟腈酶是催化羟腈化合物分解和合成的裂解酶.合成反应生成的光活性羟腈化合物是许多手性药物和农用化学品的合成前本,在有机合成中具有巨大的应用价值.通过该文的研究,为木薯羟腈酶的工业化应用和催化机制的研究奠定了坚实基础.

关键词： 不对称合成   生物还原   酶化学   催化反应  

摘要： 利用白地霉菌株和啤酒酵母催化还原α－氯代酮　４分别制得光学活性的（Ｒ）和（Ｓ）－α－氯代酶 ８，并以它们作为关键步骤合成了 Ｒｏ２５－８２１０（１）和 Ｒｏ２５－６６３０（２）．

关键词： dehydroalanine   thiols   addition   diastereoselectivity   S-alkylcysteines   asymmetric synthesis  

摘要： An efficient procedure was developed for the asymmetric synthesis of S-alkyl derivatives of (R)-cysteine by nucleophilic addition of alkanethiols ((BuSH)-S-n, (BuSH)-S-t. or tert-C5H11SH) to the C=C bond of the dehydroalanine fragment in the Ni-11 complex of the Schiffs base of Delta-Ala with (S)-2-N-(N-benzylprolyl)aminobenzophenone [(S)-BPB-Delta-Ala]Ni-11. Under conditions of thermodynamic control of the reaction, the diastereomeric excess of the complexes with the (S, R)-configuration was 88-96%. After decomposition of the complexes, ( R)-S-butylcysteine, (R)-S-tert-butylcysteine. and (R)-S-tert-pentylcysteine were isolated with an enantiomeric purity of >97%.

关键词： imines   asymmetric synthesis   amino acids   Schiff bases   alpha,beta-didehydro-alpha-amino acids  

摘要： The present paper is an overview of new methods for the asymmetric synthesis of different types of alpha-amino acids. These methods are based on alkylation and condensation reactions of glycine and alanine imine derivatives, which can be carried out under very mild and simple reaction conditions. The enolates generated from these types of reagents are very soft and can be alkylated in a highly diastereoselective manner, even at room temperature, by using chiral templates or asymmetric PTC conditions. These methodologies afford monoalkylated and dialkylated alpha-amino acids as well as heterocyclic derivatives. In the case of cyclic imine derivatives with oxazinone or pyrazinone structures, the condensation reaction under PTC conditions or with Eschenmoser's salt allows the preparation of chiral alpha,beta-didehydro-alpha-amino acid derivatives which can be hydrogenated, cyclo-propanated or submitted to Diels-Alder cycloadditions to afford N-methylated and cyclic alpha-amino acids.

关键词： amino acids   asymmetric synthesis   pyrazinones   phase-transfer catalysis   palladium  

摘要： (6R)-6-Isopropyl-3-methyl-5-phenyl-1,2,3,6-tetrahydro-2-pyrazinone, obtained from (R)-valine and (S)-alanine, is highly diastereoselectively alkylated at room temperature by: a) activated alkyl halides under solid-liquid PTC conditions, b) non-activated alkyl halides with organic bases, c) electrophilic olefins employing both solid-liquid PTC conditions and organic bases, and d) allylic carbonates by means of palladium catalysis under neutral conditions. Enantiomerically pure (S)-alpha-methyl alpha-amino acids 8 are obtained by hydrolysis of the alkylated pyrazinones.