环丙烷氨基酸合成研究进展

本文综述了合成环丙烷氨基酸类化合物的近期研究进展。制备方法包括对简单氨基酸衍生物的亲核环烷基化、类卡宾加成以及简单环丙烷化合物的衍生化合成等。在手性合成中利用了天然或合成的光学活性化合物。     

Stereoselective synthesis of activated cyclopropanes with an α-pyridinium acetamide bearing an 8-phenylmenthyl group as the chiral auxiliary

The reaction between an α-pyridinium acetamide bearing an 8-phenylmenthyl group as the chiral auxiliary and β-substituted methylidenemalononitriles gave rise to trans-cyclopropanes with diastereomeric ratios of up to 98:2. For most of the reactions, the absolute stereochemistry of the major product was found to be opposite of that of the major products of the reaction of the corresponding ester series, which also utilized the 8-phenylmenthyl group.     

多取代苯的自位硝化和溴化反应

系统地研究了苯环取代烷基和侧链取代基对自位硝化反应的影响，详细地讨论了脱溴甲基的机理，多取代苯的正常硝代与自位３硝化是一对竞争反应；侧链酯基的存在是自位硝化的必要条件；苯环上取代基的空间效应是自位硝化的充分条件，六元环过滤态很可能为自位硝化反应提供了一个能量有上利的途径。     

Synthetic studies toward the disorazoles: synthesis of a masked northern half of disorazole D1 and a cyclopropane analog of the masked northern half of disorazole A1

The synthesis of a masked northern half of the natural product disorazole D₁ and a cyclopropane analog of the masked northern half of disorazole A₁ is described. The synthesis involves in both cases as key steps a Z-selective Wittig olefination and a Sonogashira cross-coupling reaction.     

Simple Approach to the Highly Stereoselective Synthesis of trans-1,2-Cyclopropane Derivatives

In the presence of KF·2H2O, furoylmethyltriphenylarsonium bromide （1a） or thienoylmethyltriphenylarsonium bromide （1b） reacted with 2-[（un）substituted benzylidene]malononitrile （2） in chloroform at room temperature to give trans-3,3-dicyano-1-furoyl-2-[（un）substituted phenyl]cyclopropane （3a） or trans-3,3-dicyano-1-thienoyl-2- [（un）substituted phenyl]cyclopropane （3b） respectively in good yield with high stereoselectivity. The structures of product 3 were confirmed by IR, MS, 1^H NMR, 1^H-1^H COSY and microanalysis. The relative configuration of product 3 was determined by 1^H-1^H NOESY technique. The mechanism for the formation of product 3 was also proposed.     

Concise synthesis of multiply substituted stereodefined cis,cis-2,4-diene-1,6-dials, cis,cis-2,4-diene-1,6-diols and further applications

Reactions of 1,4-dilithio-1,3-dienes with DMF afforded multiply substituted stereodefined cis,cis-2,4-diene-1,6-dials in high yields. Treatment of these 1,6-dials with LiAlH₄ or RLi resulted in the formation of their corresponding 1,6-diols. These bifunctional compounds, cis,cis-2,4-diene-1,6-dials and -1,6-diols are otherwise not readily available. Further reaction of these 1,6-diols with an aldehyde catalyzed by strong acids led to the formation of oxacycles of novel structures.     

Novel functionalised P-ligands: advances and application

Novel endo- and exocyclic phosphine ligands possessing different functionalities obtained by reduction of the PO precursors with desired stereochemistry are discussed. The diastereoselective deoxygenation including the catalytic reduction processes, the factors defining the reactivity and the role of the substituents on the stability of phosphorus atom configuration in a series of 3-aryl-3-phosphabicyclo[3.1.0]hexanes are reported. The complexation features of the ligands with Rh(III) and Pd(II) were examined and Rh(III) complexes were tested in styrene hydroformylation showing the structure-activity dependence.     

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs (abbreviated XBAYs) were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the ¹H NMR chemical shifts (^δH(CH=N)) and ¹³C NMR chemical shifts (^δC(CH=N)) of the CH=N bridging group from di-substituted to multi-substituted XBAYs was made based on a total of 182 samples of XBAYs, together with the NMR data of other 129 samples of di-substituted XBAYs quoted from literatures. The results show that the substituent specific cross-interaction effect parameter \begin{document} $\left(\Delta\left(\displaystyle\sum\sigma\right)^2\right)$ \end{document} plays an important role in quantifying the ^δC(CH=N) values of XBAYs, but it is negligible for quantifying the ^δH(CH=N) values; the other substituent parameters also present different influences on the ^δC(CH=N) and ^δH(CH=N). On the whole, the contributions of X and Y to the ^δC(CH=N) of XBAYs are balanced, but the ^δH(CH=N) values of XBAYs mainly rely on the contributions of X.     

I2/K2CO3-promoted ring-opening/cyclization/rearrangement/aromatization sequence: A powerful strategy for the synthesis of polysubstituted furans

An efficient and straightforward synthetic method has been developed for the preparation of 4-cyanofuran-3-carboxylate derivatives via iodine/potassium carbonate-promoted ring-opening/cyclization/rearrangement domino reaction of 1-cyanocyclopropane-1-carboxylates, which are a wide range of structurally interesting and pharmacologically significant compounds.     

Temporary Generation of a Cyclopropyl Oxocarbenium Ion Enables Highly Diastereoselective Donor–Acceptor Cyclopropane Cycloaddition

A novel formal [3+2] cycloaddition of cyclopropylacetals and aldehydes was developed, and the resulting trisubstituted tetrahydrofurans display three new chiral centers formed with highly diastereoselectivity. This method is stereocomplementary to most previously reported cycloadditions of malonate diesters, relies on the transient generation of cyclopropyl oxocarbenium ions, proceeds under mild conditions, and is based on the concept of temporary activation of an otherwise inert protecting group.