Total Synthesis of Indolizidine Alkaloid (−)-209D: Overriding Substrate Bias in the Asymmetric Rhodium-Catalyzed [2+2+2] Cycloaddition
作者:Robert T. Yu、Ernest E. Lee、Guillaume Malik、Tomislav Rovis
DOI:10.1002/anie.200805455
日期:2009.3.16
an efficient [2+2+2] cycloaddition between terminal alkyl alkynes and alkenyl isocyanates (see scheme). The cycloaddition proceeds through a CO migration pathway, and facilitates a rapid four‐step asymmetric synthesis of indolizidine (−)‐209D.
对!你让我问好:在铑上使用手性联苯基亚磷酰胺配体提供了末端烷基炔烃和烯基异氰酸酯之间有效的 [2+2+2] 环加成(参见方案)。环加成通过 CO 迁移途径进行,并促进吲哚里西啶 (-)-209D 的快速四步不对称合成。
Conversion of Propargylic Alcohols to β-Oxo Esters Catalyzed by Novel Ruthenium-Phosphoramidite Complexes
作者:Stephen Costin、Nigam P. Rath、Eike B. Bauer
DOI:10.1002/adsc.200800355
日期:2008.10.6
from propargylicalcohols and carboxylic acids. Standard conditions involve cyclohexane solvent, propargylicalcohol (1.0 equiv.), carboxylic acid (1.0 equiv.), ruthenium catalyst (1.5 mol%), and 90 °C for 5–18 h. Isolated yields of the β-oxoesters range from 87 to 16% and show broad substrate generality. The reaction proceeds without racemization if a chiral propargylicalcohol is employed. The method