Synthetic approach towards cephalezomine A and phomoidride D

Abstract

Two synthetic approaches towards cephalezomine A and phomoidride D are described separately. The first approach towards cephalezomine A invented a new method for the synthesis of 3-butoxy-1-chlorobutenone and successful constructed α-O and ß' -N disubstituted dienone for a designed key intermediate of cascade cyclization by Eschenmoser coupling of thiolactam and 3-butoxy-1-chlorobutenone. The second approach towards phomoidride D systematically studied the electronic effects of different ester substituents for the phenolic oxidation and inverse electron demand Diels-Alder reaction, which resulted in the synthesis of functionalized bicyclic [2.2.1] intermediate. Base on this, a new route for the synthesis of precursor of Grob fragmentation has been established towards the total synthesis of phomoidride D by samarium diiodide mediated radical cascade cyclization.