Biocatalytic Strategy for Highly Diastereo‐ and Enantioselective Synthesis of 2,3‐Dihydrobenzofuran‐Based Tricyclic Scaffolds

Abstract

Abstract2,3‐Dihydrobenzofurans are key pharmacophores in many natural and synthetic bioactive molecules. A biocatalytic strategy is reported here for the highly diastereo‐ and enantioselective construction of stereochemically rich 2,3‐dihydrobenzofurans in high enantiopurity (>99.9% de and ee), high yields, and on a preparative scale via benzofuran cyclopropanation with engineered myoglobins. Computational and structure‐reactivity studies provide insights into the mechanism of this reaction, enabling the elaboration of a stereochemical model that can rationalize the high stereoselectivity of the biocatalyst. This information was leveraged to implement a highly stereoselective route to a drug molecule and a tricyclic scaffold featuring five stereogenic centers via a single‐enzyme transformation. This work expands the biocatalytic toolbox for asymmetric C–C bond transformations and should prove useful for further development of metalloprotein catalysts for abiotic carbene transfer reactions.