查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">This review is devoted to the stereochemistry of nucleophilic substitution reactions at phosphorus. The study of the reactions of phosphoryl group transfer is important for biological and molecular chemistry. The stereochemistry and mechanisms of S<ce:inf loc="post">N</ce:inf>1(P) monomolecular and S<ce:inf loc="post">N</ce:inf>2(P) bimolecular nucleophilic substitution reactions of organophosphorus compounds are discussed. It has been shown that hydrolysis of many natural phosphates proceeds according to the monomolecular S<ce:inf loc="post">N</ce:inf>1(P) mechanism via the formation of metaphosphate intermediate (PO<ce:inf loc="post">3</ce:inf><ce:sup loc="post">?</ce:sup>). S<ce:inf loc="post">N</ce:inf>2(P) nucleophilic substitution at chiral trivalent or pentavalent phosphorus compounds proceeds via the formation of penta-coordinated transition state or pentacoordinate intermediate.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">The manuscript describes synthesis of new chiral organosilica networks starting from modified readily available enantiopure substances such as sugars and amino acids. We report on the successful preparation of robust all-chiral organosilicas by polymerization of the homochiral monomers. When the homochiral organosilane monomers were polymerized in mixtures of polar organic solvents and water in the presence of hydrochloric acid or tetrabutylammonium fluoride as catalysts, mainly spherical microparticles were obtained due to emulsification of the hydrophobic monomers in these mixtures. Polycondensation of the chiral organosilanes in the presence of Pluronic P123 as a template produced ordered mesoporous networks. The new all-chiral materials were characterized by SEM, STEM, BET, SAXS, IR, NMR and TGA.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">Four novel isomers of norlignan glycoside were isolated from<ce:italic>Cephalotaxus oliveri</ce:italic>Mast.. Their structures were elucidated as 3<ce:italic>S</ce:italic>-4″-<ce:italic>O</ce:italic>-<ce:italic>β</ce:italic>-<ce:small-caps>d</ce:small-caps>-glucopyranosylnyasol<ce:bold>1</ce:bold>, 3<ce:italic>S</ce:italic>-4′-<ce:italic>O</ce:italic>-<ce:italic>β</ce:italic>-<ce:small-caps>d</ce:small-caps>-glucopyranosylnyasol<ce:bold>2</ce:bold>, 3<ce:italic>S</ce:italic>-4″-<ce:italic>O</ce:italic>-<ce:italic>β</ce:italic>-<ce:small-caps>d</ce:small-caps>-glucopyranosylhinokiresinol<ce:bold>3</ce:bold>, 3<ce:italic>S</ce:italic>-4′-<ce:italic>O</ce:italic>-<ce:italic>β</ce:italic>-<ce:small-caps>d</ce:small-caps>-glucopyranosylhinokiresinol<ce:bold>4</ce:bold>by extensive spectroscopic methods including 1D and 2D NMR experiments (<ce:sup loc="pre">1</ce:sup>H,<ce:sup loc="pre">13</ce:sup>C, DEPT,<ce:sup loc="pre">1</ce:sup>H–<ce:sup loc="pre">1</ce:sup>H COSY, HSQC, HMBC, ROESY) along with HR-ESIMS and comparison to literature data. Their absolute configurations were elucidated through CD spectra coupled with the quantum chemical CD calculations.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">Primary amidations of carboxylic acids<ce:bold>1</ce:bold>or<ce:bold>3</ce:bold>with NH<ce:inf loc="post">4</ce:inf>Cl in the presence of ClCO<ce:inf loc="post">2</ce:inf>Et and Et<ce:inf loc="post">3</ce:inf>N were developed to afford the corresponding primary amides in 22% to quantitative yields. Additionally, we have applied the amidation to the preparation of various amides containing hydroxamic acids and achieved the synthesis of (1<ce:italic>S</ce:italic>,2<ce:italic>R</ce:italic>)-tranylcypromine as an antidepressant medicine via Lossen rearrangement.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para id="sp0005" view="all">Achiral Schiff base complexes as catalysts for asymmetric sulfoxidation in the presence of serum albumins.</ce:simple-para><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0015" view="all">Four coordination complexes<ce:bold>ML</ce:bold>derived from an achiral Schiff base ligand (H<ce:inf loc="post">2</ce:inf>L?=?2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol) have been synthesized and characterized. A method is described for the enantioselective oxidation of a series of aryl alkyl sulfides using the coordination complexes in the presence of serum albumins (SAs) in an aqueous medium at ambient temperature. The mixture of metal complexes with serum albumins is useful for inducing asymmetric catalysis. The complex, albumin source and substrate influence stereoselective sulfoxidation. At optimal pH with the appropriate oxidant, some of<ce:bold>ML</ce:bold>/SA systems are identified as very efficient catalysts, giving the corresponding sulfoxides in excellent chemical yield (up to 100%) and good enantioselectivity (up to 94%<ce:italic>ee</ce:italic>) in certain cases. UV–visible spectroscopic data provide evidence that stronger binding between the complex and serum albumin lead to higher enantioselectivity.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">An efficient [3+3] tandem reaction between 1-phenyl-3-methyl-5-pyrazolones and 2-(1-alkynyl)-2-alken-1-ones over a tertiary amine–squaramide catalyst is described. The pyran fused pyrazolone derivatives were successfully obtained in 53–88% yields and with 62–84% ee by this synthetic methodology. This methodology involves easily accessible starting material, mild condition, satisfied yields and ee values. Additionally, when enynes were used as the substrates for the [3+3] cascade reaction, isomerized target products could be obtained directly.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">In a route towards enantiomerically enriched 1-(β-hydroxypropyl)indoles, which are potentially useful building blocks for high value-added chemicals synthesis, a kinetic resolution approach by means of lipase-catalyzed enantioselective acylation as well as hydrolysis/methanolysis has been elaborated for the first time. The enzymatic resolution of chiral<ce:italic>N</ce:italic>-substituted indole-based<ce:italic>sec</ce:italic>-alcohols was successfully accomplished, yielding both enantiomeric forms of the employed derivatives with up to >99% enantiomeric purity via an enantioselective transesterification under mild reaction conditions. The most selective resolutions were obtained using fungal (CAL-B and TLL) and bacterial (PFL and BCL) lipases and vinyl acetate as the acyl?group donor. The synthetic protocol described herein is very simple, user-friendly and efficient, thus paving the way for future access towards more complex compounds of this type. The absolute configurations of novel enantiomeric derivatives, and thus stereoselectivity of the described enzymatic reactions were confirmed by application of CDA-based NMR methodology and single-crystal X-ray diffraction analysis.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">Iodoalkenes, such as 2-iodo-bornene, 17-iodoandrost-16-ene, 3-methoxy-17-iodoestra-1,3,5(10),16-ene, 3β-hydroxy-20-iodopregna-5,20-diene and 3β-hydroxy-12-iodo-5α,25<ce:italic>R</ce:italic>-spirost-11-ene were aminocarbonylated with enantiomerically pure and racemic α-phenylethylamine as the<ce:italic>N</ce:italic>-nucleophile in the presence of palladium(0) catalysts. Monodentate and bidentate (chiral and achiral) phosphines were used as ligands in the catalytic system. All diastereoisomers of the corresponding carboxamides were characterised as pure stereoisomers using both α-phenylethylamine and iodoalkene in enantiomerically pure form. The diastereoisomers were obtained in moderate to high yields in a chemoselective reaction,<ce:italic>i.e</ce:italic>., carboxamides due to single carbon monoxide insertion were formed exclusively, with no double CO insertion leading to 2-ketocarboxamides. Diastereoselectivities of the aminocarbonylation were investigated using the<ce:italic>N</ce:italic>-nucleophile in racemic form by the systematic variation of the catalyst.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">Metal-catalyzed asymmetric transfer hydrogenation is a powerful and practical method for the reduction of ketones to produce the corresponding secondary alcohols, which are valuable building blocks in the pharmaceutical, perfume, and agrochemical industries. Hence, a series of novel chiral<ce:italic>β</ce:italic>-amino alcohols were synthesized by chiral amines with regioselective ring opening of (<ce:italic>S</ce:italic>)-propylene oxide or reaction with (<ce:italic>S</ce:italic>)-(+)-2-hydroxypropyl<ce:italic>p</ce:italic>-toluenesulfonate by a straightforward method. The chiral ruthenium catalytic systems generated from [Ru(arene)(μ-Cl)Cl]<ce:inf loc="post">2</ce:inf>complexes and chiral phosphinite ligands based on amino alcohol derivatives were employed in asymmetric transfer hydrogenation of ketones to give the corresponding optically active alcohols; (2<ce:italic>S</ce:italic>)-1-{[(2<ce:italic>S</ce:italic>)-2-[(diphenylphosphanyl)oxy]propyl][(1<ce:italic>R</ce:italic>)-1-phenylethyl]amino}propan-2-yldiphenylphosphinitobis[dichol-oro(η<ce:sup loc="post">6</ce:sup>-benzene)ruthenium(II)] acts an excellent catalyst in the reduction of<ce:italic>α</ce:italic>-naphthyl methyl ketone, giving the corresponding alcohol with up to 99% ee. The substituents on the backbone of the ligands were found to have a remarkable effect on bo
Micha? MalikPiotr CmochMykhaylo A. PotopnykS?awomir Jarosz...
6页
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="graphical" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Graphical abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" class="author" xml:lang="en" id="ab010" view="all"><ce:section-title id="st010">Abstract</ce:section-title><ce:abstract-sec id="as010" view="all"><ce:simple-para id="sp0010" view="all">A novel reaction cascade involving a Lewis acid-induced migration of an isopropylidene protecting group followed by the formation of a pyranose or furanose ring and subsequent reduction of the hemiacetal is described. Depending on the reaction conditions, as well as, the stereochemistry of the substrate, polyhydroxylated tetrahydrofurans or tetrahydropyrans can be obtained in reasonable yields. The synthons used in this transformation were prepared via a highly stereoselective one-pot tandem reaction, consisting of a 1,4-Michael addition of vinylmagnesium bromide to<ce:small-caps>d</ce:small-caps>-glucose-derived cyclohexenone followed by aldol reaction with 2,3-<ce:italic>O</ce:italic>-isopropylidene-<ce:small-caps>d</ce:small-caps>-glyceraldehyde.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
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