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有机小分子催化的不对称合成反应是目前研究最为活跃的领域之一. 不对称Strecker反应是合成光学活性α-氨基酸衍生物的有效手段. 目前报道的催化不对称Strecker反应的有机催化剂主要有手性胍类、手性(硫)脲衍生物、氮-氧偶极化合物、手性Brønsted酸等, 取得了良好的催化活性和对映选择性. 对各类有机小分子催化剂在有机催化不对称Strecker反应中的应用研究进展, 以及催化剂结构与反应条件对催化活性和不对称诱导作用的影响进行了简要评述. 相似文献
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由于手性3-取代吲哚化合物是许多具有生物活性天然产物和药物分子的核心骨架,其合成方法的研究就格外令人注目.尤其是近二十年来,利用手性金属配合物和有机小分子催化剂实现吲哚的C(3)位不对称傅-克烷基化反应已成为有机界广泛研究的热点.按照促进不对称傅-克烷基化反应的手性催化剂进行分类,就近年来其在3-取代吲哚化合物合成中的应用加以综述,并对今后的发展方向进行了展望. 相似文献
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本文报道了手性季铵盐1-7催化溴代烷与1,3-二甲基-5-甲氧基-2-二氢吲哚酮(8)的不对称3-C烷化反应, 并通过研究不同的催化剂结构、溶剂、温度及溴代烷结构对产物光学活性的影响, 讨论了不对称诱导机理. 相似文献
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A new and general synthesis of alkyl cyanoformates is presented starting from the appropriate alcohol and oxalyl chloride. This is used to prepare enantiomerically pure cyanoformates from enantiomerically pure primary and secondary alcohols. Optimal conditions for the addition of various achiral cyanoformates to aldehydes catalysed by an enantiomerically pure titanium(salen) catalyst in the presence of potassium cyanide as a cocatalyst are developed. Under these conditions, two chiral cyanoformates also reacted with aldehydes to give cyanohydrin carbonates. The stereochemistry of this process is predominantly determined by the stereochemistry of the titanium(salen) catalyst and the stereochemistry of two of the cyanohydrin carbonates was confirmed by X-ray crystallography. In a further extension of the chemistry, a homogeneous system in which the potassium cyanide/18-crown-6 complex is used as the cyanide cocatalyst has been developed and the kinetics of this reaction show that it displays first order kinetics, provided at least 2 mol % of the potassium cyanide complex are employed. 相似文献
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The optical active alkyne-bridged Mo-Co heterometal complexes are synthesized by the chiral phase transfer catalyst (N-benzylcinchorin chloride) induced metal exchange reaction. The complex is used as catalyst to promote the asymmetric addition of diethylzinc to benzaldehyde. The ee value of the product alcohol is 5.7%, which illustrates the asymmetric induction of the tet-rahedral framework chirality in asymmetric catalysis reaction for the first time. 相似文献
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通过α-(1-萘基)-N-硫代甲酰乙胺与卤代酮反应制得六个光学活性的4-烷基-3-α-(1-萘基)乙基噻唑溴化物烷基碳链长=1,2,7.11,15,21). 将其用于催化水溶液中的安息香缩合反应, 所得产物收率约20-30%具有较高的光学纯度(47-57%). 在各种缓冲溶液中测定了S(+)-4-甲基-3-α-(1-萘基)乙基噻唑氯化物(Ta)的胶团性质和由它催化的不对称安息香缩合反应. 临界胶团浓度(cmc)证明(Ta)在反应中确以胶团形式催化. 在硼砂溶液中, 安息香的收率高达61%, 光学纯度23.6%. 相似文献
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本文报道了在手性膦过渡金属配合物催化下,以对溴甲苯与6-甲基-5-庚烯-2-溴化镁(5)经不对称交叉偶联反应合成(R)-(-)-和(S)-(+_)-α-姜黄烯的方法,光学收率分别为44%e.e和50.3%e.e.(R)-(-)-α-姜黄烯经Birch还原得到(R)-(-)-β-姜黄烯.对溴苯甲醚经不对称交叉偶联、Birch还原等反应合成了(S)-(+)-γ-姜黄烯. 相似文献
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[reaction: see text] The chiral ammonium salt 3 is demonstrated to be an effective catalyst for the highly enantioselective Strecker reaction of N-allylbenzaldimines with hydrogen cyanide in CH2Cl2 solution. 相似文献
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当在Sharpless试剂中加入催化量的金属氢化物和硅胶后, 烯丙醇的不对称环氧化反应时间大为缩短, 而化学和光学产率不受影响。着重讨论了氢化钙和硅胶对Sharpless烯丙醇不对称环氧化的作用。 相似文献
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Saravanan S Sadhukhan A Khan NU Kureshy RI Abdi SH Bajaj HC 《The Journal of organic chemistry》2012,77(9):4375-4384
Recyclable chiral amide-based organocatalyst 5 efficiently catalyzed asymmetric Strecker reaction of various aromatic and aliphatic N-benzhydrylimines with ethyl cyanoformate as cyanide source at -10 °C to give a high yield (95%) of α-aminonitriles with excellent chiral induction (ee, up to 99%) with the added advantage of recyclability. Based on experimental observations a probable mechanism was proposed for this reaction. This protocol with catalyst 5 was extended for the synthesis of (R)-phenylalanine and pharmaceutically important drug intermediate (R)-3-phenylpropane-1,2-diamine in high yield with high enantioselectivity. 相似文献