Total Synthesis of (±)-trans-Dihydronarciclasine through a Highly endo-Selective Diels-Alder Cycloaddition of 3,5-Dibromo-2-pyrone

摘要

Over the past several decades, there has been tremendous interest in the synthesis of narciclasine (1), lycoricidine (2), and pancratistatin (3; Scheme 1). These naturally occurring isocarbostryls have been isolated primarily from plants of the genus Amaryllidaceae and are known to have potent antitumor and antiviral activities. The molecular basis of their anticarcinogenesis has been attributed to their inhibition of protein synthesis at the peptide-bond-forming step, except in the case of pancratistatin (3). Stimulated by the need for more potent antitumor agents with better therapeutic profiles, considerable effort has been devoted to the isolation and creation of structural congenors and analogues of these compounds.