Synthesis of the Pentacyclic Skeleton of the Aspidosperma Alkaloids Using Rhodium Carbenoids as Reactive Intermediates
作者:Albert Padwa、Alan T. Price
DOI:10.1021/jo971424n
日期:1998.2.1
derivatives was treated with rhodium(II) acetate. Attack of the amido carbonyl oxygen at the resultant rhodiumcarbenoid center produced a transient push-pull carbonyl ylide dipole which underwent an intramolecular dipolar cycloaddition reaction. A related annulation sequence was used to prepare the pentacyclic skeleton of the aspidosperma family of alkaloids. Synthesis of the required diazo imide was
The total synthesis of quebrachamine was achieved through the macrolactamization of cis-2-alkenylated indole 17, which was prepared by a Sonogashira reaction between indole 5b and piperidine 11 followed by cis-hydrogenation. We found that stoichiometric copper(I) iodide limited the undesired Glaser-type homocoupling of alkyne 11 that would otherwise take place during the Sonogashira coupling. This
binary systems of a copper compound (or metallic compounds) and an isocyanide catalyze the Michael addition reaction. As the copper component, Cu2O, metallic copper and copper acetylacetonate are effectual, whereas CuCl, CuCl2, and CuO are ineffectual. The catalyst of copper isocyanide complex is characterized by the selective activation of cyano olefin compounds such as acrylonitrile. This was demonstrated