Total Synthesis of (+)-Prunustatin A: Utility of Organotrifluoroborate-Mediated Prenylation and Shiina MNBA Esterification and Macrolactonization To Avoid a Competing Thorpe-Ingold Effect Accelerated Transesterification.

Abstract

A convergent total synthesis of (+)-prunustatin A is described through the assembly of two key fragments and a macrolactonization. Shiina MNBA couplings were used for the formation of each of the four ester bonds in the tetralactone ring, including the key macrocyclization which was essential to minimize competing Thorpe-Ingold accelerated transesterification. Other key steps included an organoboron-based prenylation using potassium prenyltrifluoroborate and a carbonyldiimidazole-mediated coupling to form the salicylamide.