Metallic Base-Induced Cycloadditions ofN-(1-Cyanoalkyl)imines viaN-Metalated Azomethine Ylides: Enhanced Reactivity and High Regio- and Stereoselectivity
Michael Addition and Alkylation of 2-Azaallyl Anions Derived from<i>N</i>-(1-Cyanoalkyl)imines, and Stereoselective Cyclization of Imine Esters or Ketones Leading to 1-Pyrrolines
The 2-azaallyl anionsderivedfrom N-(1-cyanoalkyl)imines and DBU undergo Michael addition or alkylation to produce N-(1-alkylated 1-cyanoalkyl)imines. The Michael addition of some aryl-substituted imines are highly diastereoselective. The alkylated Michael adducts are converted into lactams through a hydrolysis and recyclization sequence. Base-induced cyclization furnishes 1-pyrrolines through a cyclization
Metallic Base-Induced Cycloadditions of<i>N</i>-(1-Cyanoalkyl)imines via<i>N</i>-Metalated Azomethine Ylides: Enhanced Reactivity and High Regio- and Stereoselectivity
Lithiation of N-(1-cyanoalkyl)imines with LDA generates new N-lithiated azomethine ylide 1,3-dipoles which show enhanced reactivity toward dipolarophiles. They undergo exclusively regio- and stereoselective 3+2 cycloaddition reaction with α,β-unsaturated esters to give 1-pyrrolines after the elimination of LiCN. Metallic bases other than LDA can be also effective. Such high regio- and stereoselectivity is explained by the involvement of N-metalated azomethine ylides.
Transitioning Enantioselective Indicator Displacement Assays for α-Amino Acids to Protocols Amenable to High-Throughput Screening
作者:Diana Leung、Eric V. Anslyn
DOI:10.1021/ja8038079
日期:2008.9.17
realistic reaction sample, which was analyzed using receptor [Cu(II)(1)](2+). The experimentally determined ee using our eIDA was compared to that obtained by chiral HPLC and (1)H NMR chiralshiftreagent analysis. This gave errors of 4.7% and 12.0%, respectively. In addition to the use of ee calibration curves, an artificial neural network (ANN) was used to determine the % L-amino acid of the test samples
α-氨基酸的对映选择性指示剂置换测定 (eIDA) 在 96 孔板格式中进行,以证明该技术对对映体过量 (ee) 值的高通量筛选 (HTS) 的可行性。eIDAs 实施了手性受体 [Cu(II)(1)](2+) 和 [Cu(II)(2)](2+) 与指示剂铬天青 S。使用两种受体制作对映体过量校准曲线,然后用于分析真实的测试样品。将这些结果与之前使用传统紫外-可见分光光度计获得的结果进行比较,结果显示精度几乎没有损失,同时分析速度也有所提高。未知 ee 的缬氨酸样品是通过不对称反应合成的,以产生真实的反应样品,使用受体 [Cu(II)(1)](2+) 对其进行分析。将使用我们的 eIDA 通过实验确定的 ee 与通过手性 HPLC 和 (1) H NMR 手性位移试剂分析获得的 ee 进行比较。这分别给出了 4.7% 和 12.0% 的误差。除了使用ee校准曲线之外,还使用人工神经网络(A