联二萘酚衍生手性二胺催化的不对称Aldol反应

在10 mol%手性二胺和10 mol%手性磷酸的催化下,苯乙酮及其衍生物与三氟丙酮酸甲酯完成Aldol反应,得到80%的产率和73%ee的对映体过量产物,其结构经1H NMR和13C NMR表征.     

X-Ray Investigation of Chiral β-Hydroxyketone Derived From (+)-Isomenthone

X-ray analysis was carried out to study the molecular structure of β-hydroxyketone, which is one of the minor products of selective aldol condensation of (−)-menthone with 4-carbomethoxybenzaldehyde. The cyclohexanone ring of the compound has a practically undistorted chair conformation with an axial orientation of the 1-methyl group and the bulkiest 2-[1′-hydroxy-1′ -(4-carbomethoxyphenyl)]methyl substituent and the equatorial orientation of the isopropyl group in the 4 position. The stereochemical configuration was found to be (1R,2R,4 R, 1′ S), supporting that the compound belongs to the group of (+)-isomenthones; i.e., the starting (-)-menthone undergoes (to a certain extent) epimerization under the reaction conditions used. In crystal, there is intermolecular hydrogen bonding >C=O...HO- (the -O...H- bond length is 2.15 Å). The molecular conformation in hydroxyketone crystals differs from the one which prevails in solutions (according to previous NMR data) and which is characterized by an inverted cyclohexanone ring and intramolecular hydrogen bonding >C=O...HO.Original Russian Text Copyright © 2004 by S. V. Shishkina, T. G. Drushlyak, L. A. Kutulya, N. S. Pivnenko, and O. V. Shishkin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 933–940, September–October, 2004.     

Novel Asymmetric and Stereospecific Aziridination of Alkenes with a Chiral Nitridomanganese Complex

The addition of pyridine N -oxide is necessary to obtain high enantioselectivities in the asymmetric aziridination of styrene derivatives through transfer of a nitrogen atom from chiral, toluenesulfonic anhydride activated nitridomanganese complex 1 [Eq. (a)]. Remarkably, high stereospecificity was observed in all the aziridinations of trans- and cis-1,2-disubstituted alkenes. R¹=H, Me, nPr, iPr; R²=H, Me; Ts=p-toluenesulfonyl.     

金属络合物催化剂在不对称氮杂环丙烷反应中的研究进展

不对称氮杂环丙烷化;手性催化;金属络合物催化剂在不对称氮杂环丙烷反应中的研究进展     

Asymmetric Syntheses Vi: Asymmetric Aldol Reaction of D-Camphor Imine Derived From Benzylamine

Addition of the D-camphor imine of benzylamine to a variety of aldehydes or ketones gives diastereose-lectivities ranging from 16–70%. The d.e. value is attributed by the difference of the orientation of C-11 groups. The rotation of (5e) indicates that addition reaction occurs from the pro-R face of lithium derivative (2).     

Chiral Diamine-catalyzed Asymmetric Aldol Reaction

A highly efficient catalytic system composed of a simple and commercially available chiral primary diamine (1R,2R)-cyclohexane-1,2-diamine(6) and trifluoroacetic acid (TFA) was employed for asymmetric Aldol reaction in em-PrOH at room temperature. A loading of 10%(molar fraction) catalyst 6 with TFA as a cocatalyst could catalyze the Aldol reactions of various ketones or aldehydes with a series of aromatic aldehydes, furnishing Aldol pro- ducts in moderate to high yields(up to >99%) with enantioselectivities of up to >99% and diastereoselectivities of up to 99:1.     

手性联萘酚配合物催化的缺电子烯烃不对称环氧化反应

缺电子烯烃的不对称环氧化反应是有机合成领域最具有挑战性的课题之一。手性联萘酚配体所修饰的催化剂是一种很优异的C2轴对称手性诱导源,可以催化各种α,β－不饱和羰基化合物如α,β－不饱和酮、α,β－不饱和羧酸脂等的不对称环氧化反应,具有良好的催化活性和对映选择性。本文对由手性联萘酚类配体所修饰的小分子催化剂、聚合物负载的催化剂和自负载催化剂在不饱和羰基化合物的催化不对称环氧化反应中的应用进行了综述,探讨了催化剂结构、配位金属原子、添加物、氧化剂、溶剂和反应温度等因素对手性联萘酚催化剂催化效能和对映选择性的影响。     

手性金属络合物催化不对称Baeyer-Villiger反应

Baeyer-Villiger反应是有机化学基本反应之一,但是催化不对称Baeyer-Villiger反应的研究尚处于起步阶段。本文按手性配体的不同,评述了手性金属络合物催化不对称Baeyer-Villiger反应的研究,特别是由外消旋或前手性酮制备光学活性内酯的研究进展。     

Asymmetric Samarium-Reformatsky Reaction of Chiral alpha-Bromoacetyl-2-oxazolidinones with Aldehydes

The samarium(II) iodide mediated asymmetric Reformatsky-type reaction of chiral 3-bromoacetyl-2-oxazolidinones with various aldehydes was studied. A series of chiral 4-substituted 2-oxazolidinones 1-3 and 5,5-disubstituted "SuperQuat" oxazolidinones 4-5 were employed as chiral auxiliaries of the alpha-bromoacetic acid. The reaction of 1 with various aldehydes gave the alpha-unbranched beta-hydroxy carboximides in good yields with high diastereomeric excess values (up to >99% de). The majority of the reaction product derived from 5,5-diphenyl SuperQuat 5 were highly crystallinity; a single recrystallization yielding a diastereomerically pure product with the other diastereomer not detectable by spectroscopic methods. The absolute configurations of the beta-hydroxy carboximides were determined by signs of optical rotations of the corresponding known ethyl esters referring to the literature values. Hydrolytic cleavage of the appended of beta-hydroxy moieties from the auxiliary SuperQuats was readily achieved under mild conditions using lithium hydroxide; the corresponding carboxylic acids and the returned SuperQuats were obtained in good yields without any evidence of racemization. The first step of the reaction is the reduction of the alpha-bromo group to produce the samarium enolate, which adds to an aldehyde. The absolute configuration of the adduct (7i) derive from benzaldehyde was found to be R, with the samarium enolate favoring the transition state predicted from chelation control of the reagent; this is in analogy to the discussion that has been used for the corresponding titanium enolate. The stereochemistry of the reaction may be explained by incorporating the Nerz-Stormes-Thornton chair transition structure model.     

Asymmetric Guerbet Reaction to Access Chiral Alcohols

The first example of an asymmetric Guerbet reaction has been developed. Using commercially available, classic Noyori Ru^II‐diamine‐diphosphine catalysts, well‐known in asymmetric hydrogenation, racemic secondary alcohols are shown to couple with primary alcohols in the presence of a base, affording new chiral alcohols with enantiomeric ratios of up to 99:1. Requiring no reducing agents, the protocol provides an easy, alternative route for the synthesis of chiral alcohols. Mechanistic studies reveal that the reaction proceeds via a Ru‐catalyzed asymmetric hydrogen autotransfer process in concert with a base‐promoted allylic alcohol isomerization.     

Asymmetric Catalytic Aziridination of Cyclic Enones

The first catalytic method for the asymmetric aziridination of cyclic enones is described. The presented organocatalytic strategy is based on the use of an easily available organocatalyst that is able to convert a wide range of cyclic enones into the desired aziridines with very high enantiomeric purity and good chemical yield. Such a method may very well open up new opportunities to stereoselectively prepare complex chiral molecules that possess an indane moiety, a framework that is found in a large number of bioactive and pharmaceutically important molecules     

果糖衍生手性酮催化烯烃不对称环氧化反应的研究进展

综述了果糖衍生的手性酮催化烯烃不对称环氧化反应的发展及应用。参考文献34篇。     

手性相转移催化剂及其不对称催化反应

综述了手性季铵盐和手性冠醚两类手性相转移催化剂及其在不对称催化反应（包括加成，取代，氧化及还原等反应）中的应用，参考文献９７篇。     

碳水化合物含磷配体在不对称催化中的应用*

糖类化合物价廉易得,具有天然手性结构,糖环上的多个羟基经过修饰,可以连接多种官能团。近年来手性糖类化合物的合成与应用研究引起了人们的广泛关注,尤其是在不对称合成和催化中的应用研究已成为有机化学中非常活跃的领域。碳水化合物含磷手性配体在不对称催化反应中的应用研究进展十分迅速,本文综述了近年来碳水化合物含磷手性配体与金属形成络合物作为催化剂,在不对称催化氢化、不对称烯丙位取代和不对称氢甲酰化等反应中的研究进展。     

Chiral Borated Esters in Asymmetric Synthesis： 1. The First Asymmetric Reaction Catalyzed by Chiral Spiroborated Esters with an O3BN Framework

The first asymmetric reaction catalyzed by chiral spiroborated esters with an O3BN framework was reported. In the presence of 0.1 equivalent of (R,S)-1 or (S,S)-1, acetophenone was reduced by 0.6 equivalent of borane in THF at 0-5℃ for 2 h to give (R)-1-phenylethanol of up to 76% ee and 73% isolated yield. Influence of reaction conditions on the stereoselectivity of the reduction was investigated and a possible catalytic mechanism of the chiral spiroborated esters toward the reduction was also suggested.     

BINOL衍生的手性磷酸催化的不对称反应研究进展

综述了近年来BINOL衍生的手性磷酸作为一类强酸性Brφnsted酸催化剂,在不对称氢转移反应、Friedel-Crafts, Mannich, Aza Diels-Alder, Aza-ene-type, Pictet-Spengler等反应中的研究进展.参考文献37篇.     

Construction of Chiral All-Carbon Quaternary Stereocenters by Asymmetric Friedel-Crafts Reaction of Isatin Derivatives

Un der the catalysis of chiral Cu(ll)complex,C2 and C3 alkylati on of pyrrole and C3 alkylation of in dole were realized simulta neously.The chiral oxindole skeleton with an all-carb on quater nary stereogenic cen ter at the C3-position could be obtai ned exclusively with high yields(up to 95%)and excellent enantioselectivities(up to>99%).