Large-Scale Asymmetric Synthesis of Fmoc-(S)-2-Amino-6,6,6-Trifluorohexanoic Acid

Here we report the first large-scale synthesis of Fmoc-(S)-2-amino-6,6,6-trifluorohexanoic acid via asymmetric alkylation of chiral Ni(II)-complex of glycine Schiff base with CF₃(CH₂)₃I. The synthesis was performed on over 100 g scale and can be recommended as the most advanced procedure for reliable preparation of large amounts of enantiomerically pure Fmoc-(S)-2-amino-6,6,6-trifluorohexanoic acid for protein engineering and drug design. Chiral auxiliary used in this protocol can be >90 % recovered and reused.     

A Novel Asymmetric Total Synthesis of (+)-Artemisinin

A 12-step synthesis of the natural product (+)-Artemisinin, very active against malaria, is described. (-)-Isopulegol, which already contains two of the asymmetric centers of (+)-Artemisinin in the correct absolute configuration, was used as starting material.     

3-氨基-2-羟基-4-苯基丁酸的合成

3-氨基-2-羟基-4-苯基丁酸的合成;乌苯美司;氨基羟基苯基丁酸;合成     

Synthesis of S-[2-(4-Aminobenzenesulfonyl)ethyl] and S-[2-(3-Amino-4-methoxybenzenesulfonyl)ethyl] Thiosulfonates

Russian Journal of General Chemistry -     

4-氨基-8-去氮杂四氢叶酸二乙酯的新合成方法

针对4-氨基-8-去氮杂四氢叶酸二乙酯现有合成方法中化合物极性大、溶解度差、收率低的缺点,采用在2,4位氨基引入保护基的方法进行改进。以6-乙酰氧基-2,4-二氯吡啶并[3,2-d]嘧啶为原料,在2,4-位引入苄基后与对氨基苯甲酰谷氨酸二乙酯连接,经硼氢化钠和氯化镍还原后再脱保护,生成叶酸类抑制剂关键中间体4-氨基-8-去氮杂四氢叶酸二乙酯。此方法所需时间短,收率较高,操作及后处理方便。并对6-乙酰氧基-2,4-二氯吡啶并[3,2-d]嘧啶苄基化的选择性、硼氢化钠和氯化镍还原方法进行了讨论。此方法对于四氢叶酸类化合物的合成有重要参考意义。     

除草剂中间体R-(+)-2-(4-羟基苯氧基)丙酸酯的不对称合成

报道了一种合成苯氧丙酸类除草剂重要中间体R－（＋）－2－（4－羟基苯氧基）丙酸乙酯（即R－（＋）－HPE）的方法，以L－乳酸为起始原料，先经酯化合成L－乳酸乙酯，再与对甲苯磺酰氯反应制备L－对甲苯磺酰乳酸乙酯，再与对苯二酚综合获得R－（＋）－2－HPE，产品的总收率为72.1%。通过元素分析和红外光谱测定，确定了所合成的R－（＋）－HPE的化学结构和纯度；由旋光度的测定，确定了所合成的R－（＋）－HPE的光学纯度为95.7%。     

2-Amino-4-bromobutanoic Acid

(2S)- and (2R)-2-Amino-4-bromobutanoic acid were prepared starting from N-Boc-glutamic acid α tert-butyl ester. The double tert-butyl protection was necessary to prevent a partial racemisation during Barton’s radical decarboxylation used to transform the γ-carboxylic group into a bromide. This bromide reacted with different nitrogen, oxygen and sulphur nucleophiles to give nonnatural amino acids characterised by basic or heterocyclic side chains. The title compound was also used to prepare a conformationally constrained peptidomimetic.     

粉蠹虫性信息素的不对称合成新方法

昆虫性信息素;粉蠹虫性信息素的不对称合成新方法     

Asymmetric synthesis of (+)-phosphinothricin and (+)-2-amino-4-phosphonobutyric acid

Asymmetric synthesis of (+)-phosphinothricin, (+)-2-amino-4-phosphono-butyric acid, and their enantiomers has been achieved by the Michael addition of chiral glycine Schiff bases to vinyl phosphorus compounds.     

Synthesis of 2-Amino-4-aryl-3-cyano-4H-pyrano and 2-Amino-3-cyanothieno Derivatives of Cyclopentanonopimaric Acid

Condensation of cyclopentanonopimaric acid with malononitrile in the presence of p-methoxybenzaldehyde or elemental sulfur gave the corresponding fused 2-amino-3-cyano-4-(4-methoxyphenyl)-4H-pyrano and 2-amino-3-cyanothieno derivatives.     

3－氨基－4－硝基苯甲酸的合成

以苯甲酸为原料，经硝化、还原、乙酰化、再硝化、水解，制备了标题化合物，结果较好。     

Direct Conversion of S-(+)-Bulbocapnine into S-(+)-2-Hydroxy-10-methoxyaporphine

The opening of a methylenedioxy group with simultaneous elimination of an oxygen atom during sodium in liquid ammonia reduction is a well established process in the aporphine alkaloid series¹. It has furthermore been reported that phosphate esters of phenols are deoxygenated under similar reaction conditions². The alkaloid bulbocapnine (1) contains an aromatic methylendioxy group and a phenolic hydroxy group; it thus seemed indicated to attempt the direct removal of two oxygen atoms by treating the phosphate ester 2 with an alkali metal in liquid ammonia. We now would like to give experimental details regarding this practical step which was summarized elsewhere³.     

The Synthesis of 2-Amino-4-(4-imidazolyl)pyridines

A general synthetic scheme for the preparation of 2-amino-4,(4-imidazolyl)pyridines, potential histamine H₂ antagonists, is described. The synthesis is based on the Neber rearrangement of l,(4-pyridyl)l-alkanone oxime 0-tosylates to the appropriate α-aminoketones or α-aminoketals, which are then converted to the corresponding imidazoles. The reaction of Grignard reagents with 2-chloroisonicotinonitrile, as well as nucleophilic displacement of chloride by amines on 2-chloroisonicotinonitrile and derivatives, are discussed in relation to the preparation of the ketone intermediates.     

2-氨基-4''-溴-二苯甲酮的合成

2-氨基-4'-溴-二苯甲酮(1)是植物生长调节剂及园艺用杀菌剂异菸碱酰替苯胺的关键中间体[1] ,也是医药原料的重要中间体,可用于合成治疗眼科发炎类药物[2].文献合成路线如下:     

微生物酶催化的不对称还原反应合成(S)-(+)-4-苯基-2-丁醇

以LB培养基培养Pseudomonas monteilii TA-5,将其整细胞作为生物催化剂（Cat）,催化4-苯基-2-丁酮(1)的不对称还原反应,对映选择性地合成了(S)-(+)-4-苯基-2-丁醇。在最佳反应条件［1 10 mmol·L^-1, c（Cat） 30 g cdw·L^-1, 10%丙三醇,pH 8.0, 300 r·min^-1,于30 ℃反应24 h］下,转化率82%, ee值91%。     

A Convenient Synthesis of (S)-(+)-2-(2-Methoxyphenyl) Propanoic Acid

a short, convenient and large scale synthesis of (S)-(+)-2-(2-methoxyphenyl) propanoic acid, involving a resolution of the corresponding racemic acid with quinine, is reported.     

A Practical Synthesis of (2S, 3R)-3-Amino-2-methylpentanoic Acid from L-Aspartic Acid

L -Aspartic acid by successive N-tosylation, anhydride formation, and reduction was converted into (3S)-3-(tosylamino)butano-4-lactone ( 4 ). Electrophilic methylation of 4 , subsequent iodo-esterification and nucleophilic methylation, followed by saponification and deprotection, gave (2S, 3R)-3-amino-2-methylpentanoic acid ( 2 ) with an ee of > 99% in seven steps and in an overall yield of 34%.     

(+)-2-甲基-4-戊烯酸的合成

丙二酸二乙酯与碘甲烷反应生成二乙基甲基丙二酸酯(1). 由(1)进行皂化和脱羧反应制备2-甲基-4-戊烯酸(4).用一种新的拆分剂葡辛胺拆分(4)得到(+)-2-甲基-4-戊烯酸.     

光学纯反式-(+)-水合蒎醇的新方法合成

以3,5-二羟基-4-甲基苯甲酸甲酯为原料,通过7步反应,高产率地合成了反式-(+)-水合蒎醇[(+)-1],其结构通过IR,MS和NMR等技术进行了确认,该化合物的光学纯度e.e.高达99%.     

A Concise Total Synthesis of S-（＋）-Tylophorine

A highly efficient total synthesis of S-( )-tylophorine has been accomplished in fully asymmetric fashion.