A Convenient Synthesis of (S)-2-Methyl and (2S)-2,3-Dimethyl Butyl Phenylsulfones from (S)-(-)-3-Methyl-γ-butyrolactone

Suitably functionalized alkylphenylsulfones have been used as building blocks for the synthesis of several modified side-chains steroids¹. We describe here the synthesis of (S)-2-methyl and (2S)-2,3-dimethyl butyl phenylsulfones (4a) and (6), which can be used for the construction of the side chain of a few marine sterols² or brassinosteroids³ as well.     

DiastereoselectiveandEnantioselectiveSynthesisof(1S,2S)-2-Ethyl-1-aminocyclopropaneCarboxylicAcid

During the last decade, 1-aminocyclopropanecarboxylic acid and its derivatives (ACCS) have attracted increasing attention of organic and bioorganic chemists due to their outstanding biological properties, ranging from antimicrobial, insecticidal, plant growth and fruit ripening controls, etc.1. Moreover, the three-membered carbocycle provides building blocks of unprecedented synthetic potential because it undergoes selective ring opening, ring enlargement or cycloaddition reactions2. The mo…     

(S)-(-)-norlaudanosine和(S)-(-)-O,O-dimethylcoclaurine的合成

以高藜芦胺为起始原料,经N-磺酰化反应制得高藜芦磺酰胺(2);2分别与芳乙烯甲醚经对甲苯磺酸催化的Pictet-Spengler反应后用金属钠脱除Ts基团合成了(±)-norlaudanosine(5a)和(±)-O,O-dimethylcoclaurine(5b);使用半量拆分法,以N-乙酰-L-苯丙氨酸为拆分剂,制得(S)-(-)-5a和(S)-(-)-5b,其结构经1H NMR,13C NMR,IR,MS和HR-ESI-MS确证。     

由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法

苄氧乙基环氧乙烷;不对称合成;由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法     

(S)-1-(2-氯乙酰基)吡咯烷-2-甲酸的制备及晶体结构

以L-脯氨酸和氯乙酰氯为原料合成维格列汀的重要中间体(S)-1-(2-氯乙酰基)吡咯烷-2-甲酸(1)。甲醇体系室温挥发14 d培养得到1的无色透明块状晶体，通过单晶X-射线衍射技术对其进行结构解析。结果表明1晶胞属于正交晶系，P2₁2₁2₁空间群，分子式为C₇H₁₀NO₃Cl，相对分子质量为191.61 g/mol，立体构型和预测构型一致，确证了1的空间结构。      

Synthesis and Structure Determination of (2S, 2′S)-3-Phenyl-2-(pyrrolidin-2′-yl)- propionic Acid

Abstract

Aβ²,β³-homoproline derivative, (2S, 2′S)-3-phenyl-2-(pyrrolidin-2′-yl)propionic acid, was synthesized starting from l-proline. After preparation of the (4S, 4aS)-4-benzyl-4a,5,6,7-tetrahydro-pyrrolo-[1,2-c]pyrimidine-1,3-dione under a mild condition, the absolute configuration of target compound was assigned using 2D H-H COSY and H-H NOESY technologies.     

A Practical Synthesis of (S)-(+)-2-(6-methoxyl-2-naphthyl) propionic Acid

a-Arylpropionic acids are an important class of non-steroidal anti-inflammatory agents1,2. The therapeutic efficacy of this class of drugs is well demonstrated by the introduction and extensive use of more than a dozen compounds exemplified by ibuprofen, naproxen, ketoprofen and flurbiprofen etc. However, in recent years the use of enantiomerical pure drugs in chemotherapy is becoming almost mandatory for enhancing specificity of drug action and reducing the toxicity. This awareness led to …     

An efficient and stereoselective synthesis of (2S,1′S,2′S)-2-(carboxycyclopropyl) glycine (LCCG-I): conformationally constrained l-glutamate analogues

Conformationally restricted metabotropic glutamate receptor agonist (2S,1′S,2′S)-2-(Carboxycyclopropyl) glycine (LCCG-I) 1 have been efficiently synthesized in a stereoselective manner. A convenient five step synthesis of 1 from readily available (−)-dimenthyl (1S,2S)-cyclopropane-1,2-dicarboxylate 5 in 49% overall yield is described.     

Asymmetric synthesis of (S)- and (R)-α-methylserine based on the chiral recyclable reagent (S)-N-(2-benzoyl-phenyl)-1-benzylpyrrolidine-2-carboxamide

Both enantiomers of -methylserine were synthesized with the use of Ni^II complexes based on the chiral recyclable reagent (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide. Intermediate diastereomeric complexes were separated by crystallization of their O-acetyl derivatives.     

(S)-2-芳基丙酸不对称合成研究进展

对(S)-2-芳基丙酸类非甾体抗炎药光学纯品的不对称合成方法进行了总结和概述，从中反映近年不对称合成中新概念、新方法和新技术的应用。     

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成;二乙氧基乙酸乙酯;Horner Wadswordth Emmons反应;催化氢化;化学拆分;（S） 乙氧基（羟基苯基）     

[Mo2O2S2(S2)2][2-]的振动光谱研究

本文测定了原子簇化合物[Mo2O2S2(S2)2][2-]的红外和拉曼光谱,并在乙腈溶液中测得其共振拉曼光谱和退偏振比。利用X光晶体结构数据,对此阴离子的伸缩振动作了简化的正则坐标分析计算。所得结果可以帮助分析和归属一些Mo-Fe-S原子簇化合物的振动光谱。     

Synthesis of (S)-(−)-β-cuparenone and (S)-(−)-cuparene

A short and efficient synthesis of the title compounds is described. (S)-(−)-β-Cuparenone was prepared in 31% yield from p-tolualdehyde and mesityl oxide in eight steps. Absolute stereochemistry was established by means of a diastereoselective cyclopropanation using (R,R)-hydrobenzoin as a recoverable auxiliary.     

(S)-2-(吡咯烷基-2)-1-苯并咪唑的合成及其对Aldol反应的催化作用

L-脯氨酸与邻苯二胺反应合成了(S)-2-(吡咯烷基-2)-1-苯并咪唑(1),其结构经1HNMR和MS表征。1与X(酸或联萘酚)复配制得复合催化体系(1-X)。以丙酮和N-甲基靛红的Aldol反应为模板考察了1-X的催化活性。研究结果显示,除1-OTf的催化活性较低以外,其余1-X均具有较高的催化活性,最高产率高于99%。Aldol反应产物具有一定的手性过量,结合过渡态结构分析了手性过量的原因。     

Synthesis and structural characterization of camphanates of (−)-(2S3S,3S) and (+)-(2S,3R)-4-Phenyl-3-bromo-2-butanol diastereoisomers

The X-ray crystal structures of (–)-syn-4-phenyl-3-bromo-2-butyl camphanate (I) and (+-anti-4-phenyl-3-bromo-2-butyl camphanate (II) have been determined. Thesyn diastereoisomer of bromohydrin has the (2S,3S) absolute configuration whereas theanti diastereoisomer has the (2S,3R) absolute configuration. The crystallized derivatives I and II have been obtained by the reaction of each stereoisomer of bromohydrin, synthesized by reduction with baker's yeast, with (1S)-camphanic chloride. Crystal data: (I) C₂₀H₂₅BrO₄:M _w: 409.32; orthorhombic,P2₁2₁2₁;a=11.245(3),b=12.086(1),c=14.512(4) å; Z=4; finalR=0.053 for 1819 observed reflections. (II) C₂₀H₂₅BrO₄;M _w=409.32; monoclinic, P2₁;a=11.352(1),b=6.378(1),c=14.255(2) å,=110.38(1);Z=2; finalR=0.045 for 1672 observed reflections.     

Syntheses,spectroscopy, and catalysis of (η 4-cod)Rh(I)-complexes with (R or S)-2-(salicylaldimine)-2-phenylethanol or (rac)-2-(salicylaldimine)-1-phenylethanol

Condensation of salicyldehyde with (R or S)-2-amino-2-phenylethanol or rac-2-amino-1-phenylethanol gives enantiopure (R or S)-2-(salicylaldimine)-2-phenylethanol (R- or S-H₂L1) or (rac)-2-(salicylaldimine)-1-phenylethanol (rac-H₂L2). The Schiff bases coordinate to [Rh(η ⁴-cod)(μ-O₂CCH₃)]₂ to afford mononuclear [Rh(η ⁴-cod){(R or S)-2-(salicylaldiminato)-2-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(R- or S-HL1)] (1 or 2), or [Rh(η ⁴-cod){(rac)-2-(salicylaldiminato)-1-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(rac-HL2)] (3). The Schiff base and complexes are characterized by IR-, UV/Vis-, ¹H/¹³C-NMR-, mass-spectroscopy, circular dichroism (CD), and polarimetry. The synthetic and spectroscopic results suggest that deprotonated Schiff base coordinates to [Rh(η ⁴-cod)] as a six-membered N,O-chelate with distorted square planar geometry at rhodium. CD and polarimetry measurements show the enantiopurity of the Schiff bases as well as the complexes in solution. The in situ system composed of [Rh(η ⁴-cod)Cl]₂ and S-H₂L1 has been used as a catalyst for the reduction of acetophenone into rac-1-phenylethanol with 85% conversion in diphenylsilane at 0–5°C.     

(S)-4-羟基吡咯烷-2-酮的简便合成

(S)-3-羟基-γ-丁内酯开环制得手性3,4-二羟基丁酸甲酯(2);对2的伯羟基进行对甲苯磺酰化、仲羟基进行苄基保护得4-对甲苯磺酰氧基-3-苄氧基丁酸甲酯(5);5在氨甲醇作用下合环、脱苄基保护合成了(S)-4-羟基吡咯烷-2-酮,总收率26%,其结构经1HNMR和HR-MS确认,比旋光值与文献值相符。     

A concise synthesis of (S)-(−)-3-(2-carboxy-4-pyrrolyl)-alanine

A convergent synthesis of (S)-(−)-3-(2-carboxy-4-pyrrolyl)-alanine (CPA) 1, a non-proteinogenic amino acid is described starting from a commercially available dimethyl l-aspartate 2 in good overall yield.     

HPLC法测定(S)-2-氨基丁酰胺对映异构体

使用高效液相色谱-柱前衍生化法测定了(S)-2-氨基丁酰胺盐酸盐的对映异构体。采用梯度洗脱;流动相A为0.1 mol/L乙酸铵溶液,流动相B为乙腈溶液;流速1.5 m L/min;波长336 nm;柱温为40℃。(S)-2-氨基丁酰胺盐酸盐对映异构体的检出限和定量限分别为0.0085μg/m L和0.0319μg/m L。对映异构体的浓度在0.03~3.0μg/m L范围内线性关系良好(r2=0.9992),回收率在91.8%~104.6%之间。方法能够有效控制左乙拉西坦重要中间体(S)-2-氨基丁酰胺的光学纯度。