Helical polymer carrying helical grafts from peptide-based acetylene macromonomers: synthesis

N-Propargylamide-terminated peptide-based macromonomers with a degree of polymerization ranging from 4 to 40 were synthesized by the polymerization of gamma-benzyl and gamma-stearyl-L-glutamate-N-carboxy anhydrides initiated with propargylamine. The macromonomers took an alpha-helical structure, which was confirmed by signals at 208 and 220 nm in CD spectra. The macromonomers were subjected to polymerization and copolymerization with an alanine-derived N-propargylamide [N-(tert-butoxycarbonyl)-L-alanine-N'-propargylamide] catalyzed with (2,5-norbornadiene)Rh+[eta6-C6H5B- (C6H5)3]. It was confirmed through a CD spectroscopic study that the copolymer obtained from the copolymerization of the gamma-stearyl-L-glutamate-based macromonomer with the alanine-derived N-propargylamide had a helical polyacetylene main chain and helical polypeptide side chains.     

手性氮杂环丁烷的合成及其在不对称催化反应中的应用

综述了手性氮杂环丁烷衍生物的合成方法以及它们在不对称硼氢化反应、二乙基锌对醛的加成反应、Henry反应、Diels-Alder反应和环丙烷化反应中的应用研究进展.     

联萘衍生物作为手性配体在不对称氢化中的应用

综述了近年来联萘衍生物作为手性配体构成的金属络合物在前手性烯、酮及亚胺的不对称氢化反应中的应用。     

Helical Polymer as Mimetic Enzyme Catalyzing Asymmetric Aldol Reaction

This Communication reports optically active helical substituted polyacetylenes which solely catalyzed asymmetric Aldol reaction between cyclohexanone and p‐nitrobenzaldehyde; more importantly the helical structures are found to play crucial roles in the asymmetric catalysis, with a remarkable yield and ee (both up to 80%). A synergic effect is observed between the helical structures in the polymer main chains and the pendent prolinamide moieties for successfully catalyzing the asymmetric reaction. The role of the helical polymer backbones is further verified by tuning the relative helical structure content.     

手性氮杂卡宾金属络合物的合成及其在不对称催化反应中的应用

手性氮杂卡宾金属络合物在多种催化反应中得到了广泛的应用, 并取得了很好的研究成果. 综述了手性氮杂卡宾金属络合物的合成以及它们在催化不对称反应中的应用研究进展, 如催化α,β-不饱和酮的1,4-加成反应、酮的氢硅烷化反应、烯烃的氢化反应和烯烃的复分解反应等.     

Role of noncovalent interactions in the enantioselective reduction of aromatic ketimines with trichlorosilane

[reaction: see text] Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by a new N-methyl L-valine derived Lewis basic organocatalyst, such as 4d, with high enantioselectivity. The structure-reactivity investigation suggests hydrogen bonding and arene-arene interactions between the catalyst and the incoming imine as the main factor determining the enantiofacial selectivity.     

Synthesis and properties of helical poly(phenylacetylene) derivatives. Effect of chirality combination on the helicity

Novel 4‐ethynylphthaloyl amino acid esters carrying different terminal groups, 4‐ethynylphthaloyl glycine (1S,2R,5S)‐menthyl ester ( 1 ), 4‐ethynylphthaloyl glycine (1R,2S,5R)‐menthyl ester ( 2 ), 4‐ethynylphthaloyl L ‐leucine methyl ester ( 3 ), 4‐ethynylphthaloyl L ‐leucine (1S,2R,5S)‐menthyl ester ( 4 ), 4‐ethynylphthaloyl L ‐leucine (1R,2S,5R)‐menthyl ester ( 5 ) were synthesized and polymerized with a rhodium catalyst. Polymers with high molecular weights were obtained in 71–92% yields. The helical conformation of the polymers could be tuned by the chirality of the amino acid connected to the backbone, together with the chirality and bulkiness of the terminal pendent groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4183–4192, 2008     

联萘衍生物作为手性配体在二烷基锌和醛不对称加成反应中的应用

光学活性的联萘衍生物作为优异的手性配体应用到不对称催化中已取得了巨大进展,显示出广阔的应用前景,综述了近年来联萘衍生物小分子、树枝状大分子和高分子作为手性配体和其金属络合物作为手性催化剂在二烷基锌和醛不对称加成反应中的应用.     

不对称催化Henry反应研究进展

Henry反应是一类重要的有机反应. 按照反应中使用催化剂的种类, 分金属络合物催化、有机小分子催化、酶催化、非均相负载催化四大类, 详细介绍了不对称催化Henry反应的研究进展.     

Chirality sensing of various biomolecules with helical poly(phenylacetylene)s bearing acidic functional groups in water

Stereoregular, cis–transoidal poly(phenylacetylene)s bearing strongly acidic functional groups as pendants, such as a phosphonic acid and its monoethyl ester and a sulfonic acid, were found to interact with various biomolecules such as peptides, proteins, amino sugars, and carbohydrates in water, and the complexes exhibited characteristic induced circular dichroisms in the ultraviolet–visible region of the polymer backbones, which resulted from the formation of predominantly one-handed helical conformations. On the other hand, the sodium salt of poly[(4-carboxyphenyl)acetylene], bearing a weak acidic carboxy group, showed induced circular dichroisms only in the presence of carbohydrates and some positively charged proteins. The sensitivity of the polymers to the chirality of various biomolecules was also investigated with circular dichroism spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5039–5048, 2006     

New Chiral Substituted 8-Quinolinyl-oxazolines as Ligands for Copper(I)-catalyzed Asymmetric Cyclopropanation

ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｙｍｍｅｔｒｉｃｃａｔａｌｙｔｉｃｃｙｃｌｏｐｒｏｐａｎａｔｉｏｎｏｆｏｌｅｆｉｎｓｗｉｔｈｄｉａｚｏｃｏｍｐｏｕｎｄｓｉｓｏｎｅｏｆｔｈｅｍｏｓｔｕｓｅｆｕｌｍｅｔｈｏｄｓｆｏｒｔｈｅｓｙｎｔｈｅｓｉｓｏｆｃｈｉｒａｌｃｙｃｌｏｐｒｏｐａｎｅｓ .1Ａｎｕｍｂｅｒｏｆｅｆｆｉｃｉｅｎｔｃｈｉｒａｌｌｉｇａｎｄｓ ,ｐａｒｔｉｃｕｌａｒｌｙｂｉｓｎｉｔｒｏｇｅｎｌｉｇａｎｄｓ ,ｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄ ,ａｎｄｅｘｃｅｌｌｅｎｔｅｎａｎｔｉｏｓｅｌｅｃｔｉｖｉｔｉ…     

不对称催化反应在手性农药不对称合成中的一些应用

近十多年来，不对称催化反应在单一手性农药研发中的应用渐渐引起人们的关 注，结合自己的研究对这一领域的不对称催化反应及手性催化剂的发展进行了归纳 总结。     

Diels-Alder反应在不对称合成中的研究进展

狄尔斯-阿尔德（DA）反应自被发现以来，在有机经学中占有重要地位。对近 年来DA反应不对称合成催化剂（尤其是手性Lewis酸化合物）、手性助剂和手性双 烯三个主要方面的研究进展进行了讨论。     

Synthesis of helical poly(phenylacetylene)s bearing cinchona alkaloid pendants and their application to asymmetric organocatalysis

Four novel dynamic helical poly(phenylacetylene)s bearing cinchona alkaloids as pendant groups were synthesized starting from the commercially available cinchona alkaloids, cinchonidine, cinchonine, quinine, and quinidine, by the polymerization of the corresponding phenylacetylene monomers with a rhodium catalyst. These polymers exhibited an induced circular dichroism (ICD) in the UV–visible region of the polymer backbones in solution, resulting from the preferred‐handed helical conformation induced by the optically active cinchona alkaloid pendants. In response to the solvent used, their Cotton effect patterns and intensities were significantly changed accompanied by the changes in their absorption spectra probably due to the changes in their helical conformations, such as the inversion of the helical sense or helical pitch of the polymers. When these helical polymers were used as polymeric organocatalysts for the asymmetric conjugated addition and Henry reactions, the optically active products with a modest enantiomeric excess were obtained whose enantioselectivities were comparable to those obtained with the corresponding cinchona alkaloid‐bound monomers as the catalysts. However, we observed a unique enhancement of the enantioselectivity and a reversal of the stereoselectivity for some helical polymers, suggesting the important role of the helical chirality during the asymmetric organocatalysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Asymmetric alkylation of aromatic aldehydes with dialkylzinc catalyzed by novel amino derivatives of hydroxytetrahydropyran

Novel, specially prepared, tetrahydropyran‐based γ‐amino alcohols (S)‐2‐(aminomethyl)‐3‐hydroxy‐6‐ethoxy(phenoxy)‐tetrahydropyrans ( I ) (amino = n‐Bu₂N, piperidinyl, pyrrolidinyl, azetidinyl) were tested as catalysts in the asymmetric addition of Et₂Zn and n‐Bu₂Zn to (hetero)aromatic aldehydes. In most cases the phenoxy derivatives of I acted more enantioselectively than the ethoxy ones. The dibutylamino derivaties showed the least enantioselectivity; the pyrrolidinyl derivatives were more active as catalysts than piperidinyl and azetidinyl compounds. The highest enantioselectivity was observed in the addition of Et₂Zn to benzaldehyde in the presence of (S)‐2‐(N‐pyrrolidinylmethyl)‐3‐hydroxy‐6‐phenoxytetrahydropyran. The corresponding alcohol was prepared with 72% ee (R‐configuration). The addition of dibutylzinc proceeded slowly and less selectively. The alkylation of (hetero)aromatic aldehydes with Et₂Zn and n‐Bu₂Zn was also studied in the presence of the known optical inductor (1S,2R)‐N,N‐dibutylnorephedrine. Some chiral aromatic secondary alcohols were synthesized in high chemical yields and up to 93% ee enantioselectivity. Copyright © 1999 John Wiley & Sons, Ltd.     

Effects of cosolvents on helical substituted polyacetylene particles prepared through suspension polymerization

Acetylenic monomers undergo aqueous suspension polymerization providing particles constructed by helical substituted polyacetylene. Different from suspension polymerization of vinyl monomers, a cosolvent is indispensable to dissolve Rh catalyst and solid acetylenic monomers. The cosolvent is found to play essential roles in monomers' polymerization and the particles' formation. To systemically explore the effects of cosolvents, three monomers, M1 (achiral, liquid), M2 (achiral, solid), and M3 (chiral, solid), and six cosolvents (divided into two groups by their miscibility with water) are used for performing suspension polymerization in aqueous media at 30 °C, with Rh⁺B^– (C₆H₅)₄ as catalyst and polyvinylpyrrolidone as stabilizer. FTIR spectra and gel permeation chromatography confirm the occurrence of polymerization. Raman spectra demonstrate the high cis contents of the polymer chains. Scanning electron microscope images show that the polymer particles obtained under optimal conditions are in spherical morphology. Circular dichroism and UV‐vis spectroscopy demonstrate the helical structures of the polymer chains forming the chiral particles. Dynamic light scattering characterization is carried out to characterize the nanoparticles. The type and amount of the cosolvent affect the polymerization remarkably. Cosolvents with higher polarity lead to smaller polymer particles, while lower polar cosolvents provide larger ones. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2670–2678     

Synthesis and bifunctional asymmetric organocatalysis of helical poly(phenylacetylene)s bearing cinchona alkaloid pendants via a sulfonamide linkage

Four novel helical poly(phenylacetylene)s with amino‐functionalized cinchona alkaloid pendant groups connecting to the phenyl rings through a sulfonamide linkage were synthesized by the polymerization of the corresponding phenylacetylene monomers using Rh⁺(2,5‐norbornadiene)[(η⁶‐C₆H₅)B^?(C₆H₅)₃] (Rh(nbd)BPh₄) as the catalyst. The optically active sulfonamide‐linked polymers adopted a helical conformation with an excess of one‐handedness as supported by the appearance of the induced Cotton effects in the main‐chain chromophore regions, and efficiently catalyzed the enantioselective methanolytic desymmetrization of a cyclic anhydride and aza‐Michael addition of aniline to chalcone, thereby producing the corresponding optically active products up to 86% enantiomeric excess. However, their enantioselectivities from the methanolytic desymmetrization were slightly lower than those catalyzed by the corresponding cinchona alkaloid‐bound monomers. On the other hand, during the asymmetric aza‐Michael addition, a unique enhancement of the enantioselectivity was observed for several sulfonamide‐linked helical polymers, and thus affording a remarkably higher enantioselectivity compared to those of the corresponding monomers and nonhelical polymers bearing the identical cinchona alkaloid residues. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2869–2879