Chemo-enzymatic synthesis of equisetin

Abstract

We here report that the biosynthesis of equisetin, a fungal tetramate natural product with potent anti-infectious activity, relies on Fsa2, a Diels–Alderase that constructs the trans-decalin system of the molecule in a stereo-selective manner. This finding led to the development of a concise chemo-enzymatic route toward the synthesis of equisetin, which involves facile preparation of a linear polyene precursor via 7-steps and Fsa2 activity for equisetin maturation through an intramolecular Diels–Alder reaction, thus exemplifying the significance of the combination of chemical and biological methods to achieve structurally complex cyclic natural products and their derivatives.