新轴手性N,N-Dioxide Biscarbolin衍生物催化酮亚胺的不对称硅氢化反应

以L-色氨酸为原料合成了5个伯酰胺结构的轴手性双咔啉N—O催化剂N2,N2'-二氧-9,9'-二甲基-3,3'-取代甲酰胺-β-双咔啉(4A~4E),并用于不对称催化酮亚胺的还原反应.结果表明,催化剂的催化转化率较高(80%~98%),立体选择性(e.e.值)较好,其中催化剂N2,N2'-二氧-9,9'-二甲基-3,3'-环己基甲酰胺-β-双咔啉(4B)的催化转化率达到了98%,e.e.值达68%.     

Direct Synthesis of Chiral Allenoates from the Asymmetric C?H Insertion of α‐Diazoesters into Terminal Alkynes

The asymmetric C H insertion of α‐diazoesters into 1‐alkynes was achieved using chiral cationic guanidinium salts and copper(I) complexes. Optically active 2,4‐disubstituted allenoates were generated under mild reaction conditions from various α‐diazoesters and 1‐alkynes in high yield (up to 99 %) and enantioselectivity (up to 97:3 e.r.). Control experiments excluded the possibility of an asymmetric isomerization of alkynoates.     

Direct Synthesis of Chiral Allenoates from the Asymmetric CH Insertion of α‐Diazoesters into Terminal Alkynes

The asymmetric C? H insertion of α‐diazoesters into 1‐alkynes was achieved using chiral cationic guanidinium salts and copper(I) complexes. Optically active 2,4‐disubstituted allenoates were generated under mild reaction conditions from various α‐diazoesters and 1‐alkynes in high yield (up to 99 %) and enantioselectivity (up to 97:3 e.r.). Control experiments excluded the possibility of an asymmetric isomerization of alkynoates.     

Simple and Effective Synthetic Approach to Chiral 2-Amino-4-piperidinyl Pyridine Derivatives

A facile way has been developed to provide a series of novel chiral N-(4-(piperidin-1-yl)pyridin-2-yl)amide derivatives as potential stereoselective catalysts. The key intermediate, 2-amino-4-piperidinyl pyridine, was obtained by nucleophilic substitution of 2-amino-4-chloropyridine with piperidine in good yields (up to 96%). The total control of enantioselectivity was obtained for the synthesis of L-proline and (R)-1,1′-bi(2-naphthol) derivatives.     

Catalytic effect and recyclability of imidazolium-tagged bis(oxazoline) based catalysts in asymmetric Henry reactions

Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C(2)-symmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered. The catalysts based on the new ligands and Cu(OAc)(2)·H(2)O were applied in asymmetric Henry reactions between various aldehydes 3 and CH(3)NO(2)4. The catalysts achieved a high level of enantioselectivity; product (R)-5n was attained at 94% ee in MeOH. Moreover, the catalyst could be recycled 6 times without an obvious loss of activity or enantioselectivity. In addition, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity.     

Applications of 4,4'-(Me3Si)2-BINAP in transition-metal-catalyzed asymmetric carbon-carbon bond-forming reactions

[structure: see text] A recently developed BINAP derivative with trimethylsilyl substituents on the 4- and 4'-positions of the binaphthyl skeleton, 2,2'-bis(diphenylphosphino)-4,4'-bis(trimethylsilyl)-1,1'-binaphthyl (tms-BINAP), was used in a variety of transition-metal-catalyzed asymmetric carbon-carbon bond-forming reactions. In pi-allylpalladium-mediated reactions, tms-BINAP gave better enantioselectivity than the unsubstituted BINAP, and the origin of the improved enantioselectivity was gained from an X-ray structural study of [Pd(eta(3)-C(3)H(5))((R)-tms-BINAP)]ClO(4).     

(2<Emphasis Type="Italic">E</Emphasis>)-4-hydroxyalk-2-enals and 2-substituted furans as products of reactions of (2<Emphasis Type="Italic">E</Emphasis>)-4,4-dimethoxybut-2-enal with Grignard compounds

Methods have been developed for the synthesis of (2E)-1,1-dimethoxyalk-2-en-4-ols and (2E)-4-hydroxyalk-2-enals by reaction of (2E)-4,4-dimethoxybut-2-enals and Grignard compounds. Thermal isomerization of (2E)-4-hydroxyalk-2-enals gave the corresponding 2-alkylfurans.     

Self-supported heterogeneous titanium catalysts for enantioselective carbonyl-ene and sulfoxidation reactions

A new strategy for the heterogenization of chiral titanium complexes was developed by the in situ assembly of bridged multitopic BINOL ligands with [Ti(OiPr)4] without using a support. The assembled heterogeneous catalysts (self-supported) showed excellent enantioselectivity in both the carbonyl-ene reaction of alpha-methylstyrene with ethyl glyoxylate (up to 98 % ee) and the oxidation of sulfides (up to >99 % ee). The catalytic performance of these heterogeneous catalytic systems was comparable or even superior to that attained with their homogeneous counterparts. The spacers between the two BINOL units of the ligands in the assembled catalysts had significant impact on the enantioselectivity of the carbonyl-ene reaction. This demonstrates the importance of the supramolecular structures of the assemblies on their catalytic behavior. In the catalysis of sulfoxidation, the self-supported heterogeneous titanium catalysts were highly stable and could be readily recycled and reused for over one month (at least eight cycles) without significant loss of activity and enantioselectivity (up to >99.9 % ee). The features of these self-supported catalysts, such as facile preparation, robust chiral structure of solid-state catalysts, high density of the catalytically active units in the solids, as well as easy recovery and simple recycling, are particularly important in developing methods for the synthesis of optically active compounds in industrial processes.     

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。     

新型树状结构手性联二萘酚衍生物的合成及催化性能研究

报道了树状结构的手性联二萘酚(BINOL)配体的合成及其在二乙基锌对醛的不对称加成反应中的应用.(R)-2,2′-二羟基-1,1′-联萘-3,3′-二羧酸与末端为氨基的Frechet聚芳醚型树状分子经缩合反应,以中等产率得到0～3代的树状分子配体,用¹HNMR,IR和MALDI-TOF质谱进行了结构表征.这些树状手性配体与Ti(OPrⁱ)₄在无水甲苯溶液中形成的配合物是二乙基锌对醛不对称加成反应的高效催化剂,树状分子载体的体积对催化剂的对映选择性没有明显的影响.以邻氯苯甲醛为底物时,反应的对映选择性随树状分子代数的增加而有所提高.     

Asymmetric platinum group metal-catalyzed carbonyl-ene reactions: carbon-carbon bond formation versus isomerization

A comparative study of the carbonyl-ene reaction between a range of 1,1'-disubstituted or trisubstituted alkenes and ethyl trifluoropyruvate catalyzed by Lewis acid-platinum group metal complexes of the type [M{(R)-BINAP}]2+ (M = Pt, Pd, Ni; BINAP is 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) revealed subtle but significant differences in their reactivity. For instance, the palladium-based Lewis acid [Pd{(R)-BINAP}]2+ catalyzes the ene reaction between methylene cycloalkane to afford the expected alpha-hydroxy ester in good yield and excellent diastereo- and enantioselectivity. In contrast, under the same conditions, the corresponding [M{(R)-BINAP}]2+ (M = Pt, Ni) catalyzes isomerization of methylene cycloalkane and the ene reaction of the resulting mixture of methylene cycloalkane and 1-methylcycloalkene at similar rates to afford a range of -hydroxy esters in high regioselectivity, good diastereoselectivity, and good to excellent enantioselectivity. In addition, [Pt{(R)-BINAP}]2+ also catalyzes postreaction isomerization of the ene product as well as consecutive ene reactions to afford a double carbonyl-ene product. The sense of asymmetric induction has been established by single-crystal X-ray crystallography, and a stereochemical model consistent with the formation of (S)-configured -hydroxy ester has been proposed; the same model also accounts for the observed exo-diastereoselectivity as well as the level of diastereoselectivity.     

两组手性β-氨基醇对前手性酮的不对称催化还原研究

以合成的两组手性催化剂,（S）-二苯基脯氨醇（1）和（2S）-（二苯基羟甲基）-4苯氧基-四氢吡咯（2）,（R）-2-氨基-1,1-二苯基-3．（2’-萘基）-1-丙醇（3）和（R）-1-（1’-氨基-2’-萘乙基）-环戊醇（4）,用于六种前手性酮的不对称硼烷还原反应,比较其还原结果,发现（2）的性能优于（1）,（4）优于（3）。因此认为催化剂中取代基的引入以及含有刚性骨架均有利于对映选择性的提高。     

Zirconium-substituted isopolytungstates: structural models for zirconia-supported tungsten catalysts

The synthesis and characterization of a series of mixed W-Zr polynuclear Lindqvist-type complexes, deriving from hexatungstate [W6O19]2-, are described in this work. This family of compounds is built from {W5O18Zr}2- moieties as shown by the X-ray structures of the monomeric [W5O18Zr(H2O)(3-n)(DMSO)n]2- (n = 1 and 2) and dimeric [{W5O18Zr(mu-OH)}2]6- anions. A comprehensive spectroscopic study (183W NMR, FTIR, Raman, EXAFS, and EPR) of these compounds is presented. The goal of incorporating Zr(IV) cations into an oxotungstic core is to obtain spectroscopic models that could mimic the interactions that develop in supported catalysts between the active phase and the supporting oxide. This work tends to show that these molecular compounds can be regarded as soluble structural analogues of WOx/ZrO2 catalysts, which are interesting candidates for the skeletal isomerization of light n-alkanes.     

The effect of hydrogen bond donors in asymmetric organocatalytic conjugate additions

A series of primary amine organocatalysts with various hydrogen bond donors were prepared and examined in the conjugate addition of isobutyraldehyde and acetone to trans-β-nitrostyrene and (E)-methyl 2-oxo-4-phenylbut-3-enoate. The effect of N–H acidity and hydrogen-bonding modes of the catalysts on the catalytic activity and enantioselectivity was studied. The experimental results did not support a general correlation of N–H acidity and hydrogen-bonding modes with catalytic activity and enantioselectivity. The catalysts with double hydrogen-bonding interactions provided better catalytic activities and enantioselectivities than the catalysts with single hydrogen-bonding interactions for the reaction of trans-β-nitrostyrene. The catalyst with the most acidic N–H bond showed the best catalytic activity and enantioselectivity for the reaction of (E)-methyl 2-oxo-4-phenylbut-3-enoate. These results suggest that the effect of hydrogen bond donors in organocatalytic reactions may be highly dependent on the substrates and the reaction conditions.     

Binuclear versus mononuclear copper complexes as catalysts for asymmetric cyclopropanation of styrene

A number of (S)-(−)-2-amino-1,1-diaryl-1-propanol compounds have been synthesized. They were used to form the binuclear copper complexes through a spontaneous assembly of the individual components, the β-aminoalcohol, 2-hydroxy-5-methyl-1,3-benzenedialdehyde, and copper acetate monohydrate, in methanol. These binuclear complexes were examined as asymmetric catalysts for cyclopropanation of styrene by ethyl diazoacetate. Moderate improvement in enantioselectivity has been observed for the binuclear versus mononuclear copper complexes. The e.e. values up to 87% for trans and 93% for cis products and the ratio between trans and cis products up to 9:1 have been obtained.     

Cationic Pd(II)-catalyzed enantioselective cyclization of aroylmethyl 2-alkynoates initiated by carbopalladation of alkynes with arylboronic acids

A cationic palladium(II)-catalyzed enantioselective intramolecular addition of vinylpalladium species to ketones initiated by the carbopalladation of alkynoates under mild conditions without a Pd(II)/Pd(0) redox system was developed with high yield and enantioselectivity. This cascade reaction provides an efficient method for the construction of optically active hydroxylactones.     

Improved Catalysts for the Iridium‐Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols Based on Charton Analysis

An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air‐stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes that were not accessible previously have been obtained with high levels of enantioselectivity, thus validating the initial hypothesis regarding the selected ligand‐design elements. A rationale for the high enantioselectivities achieved in most cases is also presented.     

Diborane(4) compounds with bidentate diamino groups

The reaction between B(2)(NMe(2))(4) and 1,2-(NH(2))(2)-4-Bu(t)C(6)H(3) affords the diborane(4) compound 1,2-B(2){1,2-(NH)(2)-4-Bu(t)C(6)H(3)}(2) as the exclusive product whilst the reaction between rac-1,2-(NH(2))(2)C(6)H(10) and B(2)(NMe(2))(4) also affords only the 1,2-isomer, i.e. 1,2-B(2){1,2-(NH)(2)C(6)H(10)}(2), which is shown to be the more stable isomer by computational methods. The previously reported compounds 1,1-B(2){1,2-(NH)(2)C(6)H(4)}(2) and 1,2-B(2){1,2-(NH)(2)C(6)H(4)}(2) both react with four equivalents of Bu(n)Li to give what are presumed to be tetra-anions which react further with MeI, SnClMe(3) or SnClPh(3) to give the tetrasubstituted products 1,1-B(2){1,2-(NMe)(2)C(6)H(4)}(2), 1,1-B(2){1,2-(NSnMe(3))(2)C(6)H(4)}(2) and 1,2-B(2){1,2-(NSnPh(3))(2)C(6)H(4)}(2) respectively. The compound 1,1-B(2){1,8-(NH)(2)C(10)H(6)}(2) has also been prepared from the reaction between B(2)(NMe(2))(4) and 1,8-diaminonaphthalene. Lithiation and subsequent reaction with SnClMe(3), SnCl(2)Me(2) or SnCl(2)Ph(2) affords 1,1-B(2){1,8-(NSnMe(3))(2)C(10)H(6)}(2), 1,1-B(2){1,8-(N(2)-μ-SnMe(2))C(10)H(6)}(2) and 1,1-B(2){1,8-(N(2)-μ-SnPh(2))C(10)H(6)}(2) respectively. All new compounds have been characterised by X-ray crystallography.     

Probing the mechanisms of enantioselective hydrogenation of simple olefins with chiral rhodium catalysts in the presence of anions

The strong influence of various anions upon the hydrogenation of 2-phenyl-1-butene, catalyzed by chiral rhodium catalysts was investigated. Both sulfonates and halides exert large increases in the enantioselectivity when [Rh[(-)-bdpp](NBD)]ClO4 (bdpp = 2,4-bis(diphenylphosphino)pentane, NBD = 2,5-norbornadiene) is used as the catalyst precursor at high pressures (70 atm) of dihydrogen in nonpolar solvents. A dihydride mechanism similar to that for Wilkinson's catalyst [RhCl(PPh3)3] was shown to be operating at both high- and low-pressure conditions through a combination of catalytic studies, 31P, 1H and parahydrogen-induced polarization (PHIP) NMR experiments. With sulfonate and in neat methanol, however, a mechanistic switch takes place from a dihydride route (dihydrogen addition before olefin binding) at high pressure to an unsaturate route (olefin binding before dihydrogen addition) at low pressures (<30 atm). Olefin isomerization is inhibited by halide addition, but occurs with sulfonate and in neat methanol through what is most likely a pi-allyl mechanism. A detailed understanding of the effects of addition of these anions is crucial for development of new classes of catalysts capable of efficient enantioselective reduction of prochiral olefins lacking a secondary polar binding group.     

有机钛化学——Ⅳ.某些新型双和单(烯基环戊二烯基)钛衍生物的合成与催化烯烃异构化

用几种不同路线设计和合成了16个新型的烯基取代环戊二烯及其钛衍生物。取代环戊二烯基钛催化剂在烯烃异构化反应中具有较高的活性和选择性。对反应机理进行了初步的研究。