Preparation of (1R∗,2S∗,5R∗,6R∗)-1-Methyl-2,5,6-Tribromo-Cyclooctane and 3-Methyl-6,7-Dibromocyclooctene

Abstract

Reaction of 4,5-dibromobicyclo[6.1.0]non-4-ene with anhydrous AlBr₃ forms (1R?,2S?,5R?,6R?)-1-methyl-2,5,6-tribromocyclooctane and 3-methyl-6,7-dibromocyclooctene.

     

(1R,6R)-(+)-鱼腥藻毒素的合成

鱼腥藻毒素(Anatoxin-a)是自兰藻类水华鱼腥藻(Anabaena flos-aquae)中分离的一种氮杂双环胺类生物碱,其化学结构及绝对构型经X光晶体衍射法测定分析为:(1R,6R)(+)-2-乙酰基-9-氮双环[4.2.1]壬-2-烯,简称为AnTX-a。     

Synthesis and Crystal Structure of 5（R）-（1R,2S,5R）-Menthoxy-4（R）- N-cyclohexylaminobutyrolactone

1INTRODUCTION Substitutedγ-butyrolactones are a group of impor-tant compounds containing unique carbon skeleton of butyrolactone which is widely present in many natural products and have received considerable interest because of their biological and medicinal properties[1～4].Therefore,much attention has been paid to the new asymmetric methods for synthesi-zing these interesting compounds[5～11].The prece-ding results led us to explore the possibility of using cyclohexylamine to convert5(…     

Crystal Structure of (1R,4R;1S,4S)2-Amino-3-Cyano-1,4-Diphenyl-2-Cyclopentene-1-ol

1INTRODUCTIONIntheearly1970'sthreegroupsofinvestigatorsL,~,'foundthatlow-valenttita-nium,preparedbythereactionofstrongreducingagentswithtitaniumtrichlorideortitaniumtetrachlorideintetrahydrofuran,canabstractoxygenfromketonesoraldehydes,leadingtotheforma-tionofolefins.Theinterestinthereactioninducedbylow--valenttitaniumreagentsisincreasingandalargenumberoffunctionalgroupscanbereduceds4-6).Recent-ly,wefoundthatthetitlecompoundisObtainedbycy-cllzatlonreactionof(3--oxo-1,3-diphenyl)propyl-pro…     

Homogeneous and Solid-Gas Hydrogenation of Alkynes in the Presence of the Clusters Fe3(CO)9(ε-RC2 R 1) {R=R 1=Ph, Et; R=Me, R 1=Ph}: Characterization of New Metallacyclic Derivatives

The clusters Fe₃(CO)₉(RC₂ R ¹) (R=R ¹=Ph, Et; R=Me, R ¹=Ph), complexes 1a, 1b, 1c, containing an alkyne bound in perpendicular fashion with respect to a cluster edge, catalyze the hydrogenation of some acetylenes either under homogeneous and solid–gas conditions. We hypothesize that cluster catalysis occurs and that the catalytic activity is related to the coordinating ability of the alkynic substrates. Competition between hydrogenation and formation of metallacyclic byproducts occurs. The new metallacyclic derivatives Fe₃(CO)₆(-CO)₂{(RC₂ R ¹)(R ²C₂ R ³)}, Fe₂(CO)₆{(RC₂ R ¹)(R ²C₂ R ³)} {R=R ¹=Et, R ²=R ³=H, Ph; R ²=Me, R ³=Et, Ph; R ²=H, R ³=Bu ^t . R=R ¹=Ph, R ²=Me, R ³=Et, Ph} (complexes 2, 3) were found both in the homogeneous reaction mixtures and after the solid–gas reactions. The formation of these products lowers the catalytic activity.     

达玛烷皂苷Ginsenoside Re与Notoginsenoside R1的全合成

采用汇聚式合成的方式，充分利用原人参三醇各羟基活性的差异，采用高效的区域选择性保护策略，并以Au（I）催化的糖苷化反应对达玛烷20位大位阻酸敏感羟基和6位羟基及6-O-Glc'糖基2位羟基连续三次糖苷化，以最长线性13步分别以5.1%和4.5%的收率合成了天然双糖基达玛烷皂苷Ginsenoside Re（1）和Notoginsenoside R₁（2）.     

(1R,2R)环己二胺Schiff碱双核配合物的合成与表征

合成了二(3-羧基水杨醛叉)缩(1R,2R)环己二胺Sch iff碱配体(H4DS)及其Cu(Ⅱ)和N i(Ⅱ)的同双核配合物.用元素分析,IR光谱和1H NMR对配合物的组成和结构进行了表征;用循环伏安法测定了配合物Cu2DS.2H2O的电化学性质.     

Les cations ammoniums chiraux de type [R1R2R3R4N]+, de nouveaux templates pour les réseaux bimétalliques à pont oxalate

Chiral ammonium cations of the type [R¹R²R³R⁴N]⁺, new templates for a new family of bimetallic oxalate bridged networks. This work deals with the obtention of a new family of bimetallic [R¹R²R³R⁴N][MnCr(C₂O₄)₃] oxalate bridged 2D networks templated by chiral ammonium cations of the type [R¹R²R³R⁴N]⁺, in which R stands for n-alkyl groups from methyl to dodecyl. To cite this article: M. Gruselle et al., C. R. Chimie 6 (2003).     

Chemoenzymatic synthesis of 1α,24(R)-dihydroxycholesterol

1α,24(R)-Dihydroxycholesterol, which is the key intermediate for the synthesis of 1α,24(R)-dihydroxyvitamin D₃, was effectively synthesized via stereoselective esterification of the 24(R)-hydroxy group using a lipase in combination with inversion of configuration of the 24(S)-hydroxy group using the Mitsunobu reaction (R:S=99:1).     

R基团搜索技术用于HIV-1逆转录酶抑制剂的分子设计

本文采用基于R基团搜索技术的Topomer CoMFA方法对41个人类免疫缺陷病毒(HIV-1)逆转录酶抑制剂进行了三维定量构效关系(3D-QSAR)分析。所得优化模型的拟合、交互验证及外部验证的复相关系数分别为0.995、0.859和0.945。采用Topomer Search技术对ZINC数据库进行R基团的虚拟筛选,得到R贡献高的基团,以活性最高的13号分子为模板进行过滤得到1个Ra基团和20个Rb基团。并以此设计得到20个新化合物分子,其中有19个化合物的预测活性值高于13号分子。研究结果表明,所建立的Topomer CoMFA模型具有良好的稳定性和预测能力,基于R基团的Topomer Search技术可以有效筛选并设计出新的HIV-1逆转录酶抑制剂,为抗艾滋病新药设计提供了理论依据。     

R?ntgenfluorescenzanalyse

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R?ntgen-Fluorescenzspektrometer

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R?ntgenfluorescenzanalyse

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R?ntgenfluorescenzspektralanalyse

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R?ntgenfluorescenzanalyse

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R?ntgenstrahlenemissionsspektrographie

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R?ntgenbeugungsanalyse

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