Biocatalytic Olefin Difunctionalization for Synthesis of Chiral 2‐Azidoamines Using Nonheme Iron Enzymes
Abstract
Abstract Alkene difunctionalization represents an important category of reactions in organic synthesis, with a diverse array of transformations developed over the past decades for various synthetic applications. Nevertheless, the scope and diversity of biocatalytic alkene difunctionalization have been limited, constraining its synthetic utility. In this study, we repurposed nonheme iron enzymes to generate iron nitrene intermediates for alkene difunctionalization. 4‐hydroxymandelate synthase from Amycolatopsis orientalis ( Ao HMS) was successfully engineered for direct alkene aminoazidation to produce chiral 2‐azidoamines. Directed evolution was performed on Ao HMS to provide evolved variants that could utilize O ‐pivaloylhydroxylamine triflic acid as the nitrene precursor and produced various primary aminoazidation products with up to 44% yield, 44 total turnover number (TTN), and 98.5:1.5 enantiomeric ratio (e.r.). Mechanistic studies indicated that this new biocatalytic transformation proceeds through a stepwise radical addition and azide recombination pathway. This work expands the catalytic toolbox of metalloenzymes and opens up new opportunities for biosynthesis by introducing nonnatural olefin difunctionalization reactions into biocatalysis.
Article Details
Authors (6)
Anthony J. Huls
Department of Chemistry Johns Hopkins University 3400 North Charles Street Baltimore MD 21218 USA
Jordi Soler
Chemistry Research Laboratory
Yuxuan Su
Department of Chemistry Johns Hopkins University 3400 North Charles Street Baltimore MD 21218 USA
Yunfang Yang
College of Chemical Engineering Zhejiang University of Technology Hangzhou Zhejiang 310014 China
Marc Garcia‐Borràs
Institut de Química Computacional i Catàlisi and Departament de Química Universitat de Girona Girona Spain
Xiongyi Huang
Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States