Dynamic Ligand Exchange of the Lanthanide Complex Leading to Structural and Functional Transformation: One-Pot Sequential Catalytic Asymmetric Epoxidation-Regioselective Epoxide-Opening Process
摘要:
The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various a,beta-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-beta-azido-alpha-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samariurn azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
Lewis Acid Enabled Copper-Catalyzed Asymmetric Synthesis of Chiral β-Substituted Amides
作者:Mamen Rodríguez-Fernández、Xingchen Yan、Juan F. Collados、Paul B. White、Syuzanna R. Harutyunyan
DOI:10.1021/jacs.7b07344
日期:2017.10.11
are able to overcome the reactivity issues of unactivated enamides, known as the least reactive carboxylic acid derivatives, toward alkylation with organomagnesium reagents. Allowing unequaled chemo-reactivity and stereocontrol in catalytic asymmetric conjugate addition to enamides, the method is distinguished by its unprecedented reaction scope, allowing even the most challenging and synthetically
在这里,我们报告说,容易获得的基于甲硅烷基和硼的路易斯酸与手性铜催化剂结合能够克服未活化的烯酰胺(被称为反应性最低的羧酸衍生物)对有机镁试剂进行烷基化的反应性问题。在催化不对称共轭加成到烯酰胺中允许无与伦比的化学反应性和立体控制,该方法以其前所未有的反应范围而著称,即使是最具挑战性和合成上重要的甲基化也能以良好的产率和出色的对映选择性完成。该催化协议可耐受较宽的温度范围(-78 °C 至环境温度)和放大(10 g),而手性催化剂可以重复使用而不会影响整体效率。
Pyrazolopyrimidines as protein kinase inhibitors
申请人:Paruch Kamil
公开号:US20060094706A1
公开(公告)日:2006-05-04
In its many embodiments, the present invention provides a novel class of pyrazolo[1,5-a]pyrimidine compounds as inhibitors of protein and/or checkpoint kinases, methods of preparing such compounds, pharmaceutical compositions including one or more such compounds, methods of preparing pharmaceutical formulations including one or more such compounds, and methods of treatment, prevention, inhibition, or amelioration of one or more diseases associated with the protein or checkpoint kinases using such compounds or pharmaceutical compositions. The invention also relates to the inhibition of hepatitis C virus (HCV) replication. In particular, embodiments of the invention provide compounds and methods for inhibiting HCV RNA-dependent RNA polymerase enzymatic activity. The invention also provides compositions and methods for the prophylaxis and treatment of HCV infection.
Pyrazolo[1,5a]pyrimidine compounds as antiviral agents
申请人:Neogenesis Pharmaceuticals, Inc.
公开号:US20040038993A1
公开(公告)日:2004-02-26
The invention relates to the inhibition of hepatitis C virus (HCV) replication. In particular, embodiments of the invention provide compounds and methods for inhibiting HCV RNA-dependent RNA polymerase enzymatic activity. The invention also provides compositions and methods for the prophylaxis and treatment of HCV infection.
With the purpose of developing a method of preparing Z-alpha,beta-unsaturated amides, the Peterson reaction of the (triphenylsilyl)acetamide Ph(3)SiGH(2)COX (1, X = NBn2; 3, X = NMe2) with various aldehydes was examined. The reaction of aromatic aldehydes gave selectivities up to > 97:3. It was found that the selectivity was a function of the electronic nature of the aromatic ring and higher Z selectivity was attained with electron-rich aldehydes. With aliphatic aldehydes selectivities up to 92:8 were achieved, and unlike with analogous phosphorus reagents, less sterically hindered aldehydes gave higher Z selectivity. Also, 3, which has a smaller amide group than 1, tended to give rise to higher selectivity. A comparison with the reaction of trimethylsilyl analogues revealed the significance of the phenyl substituents on the silyl group.
PYRAZOLO[1,5-A]PYRIMIDINE COMPOUNDS AS ANTIVIRAL AGENTS