Construction of BCDEF Core of Andilesin C

Abstract

A synthetic study toward the BCDEF core skeleton of andilesin C is presented. Key elements involved iron-promoted intramolecular perezone-type [5 + 2] cycloaddition to install the BCD ring system simultaneously in a one-step, copper-catalyzed intramolecular cyclopropanation followed by BiCl3-promoted retro-aldol reaction to construct ring E and a one-pot manipulation involving reduction, lactonization, and isomerization to introduce the lactone ring F. We finally synthesized the congested BCDEF ring system of andilesin C, featuring four quaternary centers and two tertiary centers, by following a strategy with a 15-pot reaction and 11 purification operations.

Phosphine‐Catalyzed Domino Annulation Reactions of o‐Aminotrifluoroacetophenone Derivatives with Morita–Baylis–Hillman Carbonates: Construction of Tetrahydrofuro[3,2‐b]indolines

“…[12] An initial S N 2' attack of a Lewis base on the MBH carbonates creates allylic phosphonium/ ammonium salt intermediate with the elimination of CO 2 and t BuO À . Subsequently, the intermediate can be deprotonated by an extra base or the in situ-generated t BuO À to give allylic phosphorus/amine ylides, which can act as 1,3-dipolar C3 synthons to participate in Lewis base-catalyzed [3 + 2], [13] [3 + 3] [14] and [3 + 4] [15] annulations. On the other hand, they can also act as 1,1-dipolar C1 synthon and undergo [4 + 1] annulations (Scheme 2A).…”