Synthesis of acremines A, B and F and studies on the bisacremines.

Nils Winter,Dirk Trauner

doi:10.3762/bjoc.15.219

Abstract

The acremines are a family of meroterpenoids isolated from fungi of the genus Acremonium. Here, we present the asymmetric total synthesis of acremine F which hinges on a modestly enantioselective dihydroxylation and a subsequent kinetic resolution via a highly selective asymmetric reduction. Chemoselective oxidation of acremine F gave access to acremines A and B. The dimerization of acremine F to bisacremine E was investigated but could not be achieved, shedding light on the formation of the acremine dimers in nature.

Highlights

Endophytic fungi grow in a symbiotic relationship with their plant hosts [1], which is mediated by secondary metabolites [2]
In 2005, Torta and co-workers reported the isolation of six meroterpenoid natural products, acremines A–F from A20, a strain of Acreonium byssoides, isolated from grapevine leaves that were artificially inoculated with Plasmopora viticola (Figure 1) [3]
In 2015, Wei and co-workers discovered bisacremines E–G, the most complex members of the acremine family, from the soilderived strain A. persicinum SC0105 [4]. These natural products are presumed to be derived from two acremine F (5) units by a formal [4 + 2] cycloaddition followed by condensation and oxidation

Summary

Introduction

Endophytic fungi grow in a symbiotic relationship with their plant hosts [1], which is mediated by secondary metabolites [2]. We present the asymmetric total synthesis of acremine F which hinges on a modestly enantioselective dihydroxylation and a subsequent kinetic resolution via a highly selective asymmetric reduction. These natural products are presumed to be derived from two acremine F (5) units by a formal [4 + 2] cycloaddition followed by condensation and oxidation.

Results

Conclusion