Brønsted Acid Mediated Cyclization of Enaminones. Rapid and Efficient Access to the Tetracyclic Framework of the <i>Strychnos</i> Alkaloids
作者:Rahul V. Edwankar、Chitra R. Edwankar、Ojas A. Namjoshi、Jeffrey R. Deschamps、James M. Cook
DOI:10.1021/np200759h
日期:2012.2.24
ma alkaloids is described. Enaminone 16, synthesized in high yield, has been cyclized under the influence of a Brønsted acid to provide the core tetracyclic framework 17 of the Strychnos alkaloids in optically active form or alternatively to the β-ketoester tetrahydro-β-carboline (THBC) unit 18, by varying the equivalents of acid and the molar concentration. Attempts to utilize 18 to form the C(7)–C(16)