Abstract
Radical C(sp3)–C(sp3) bond formation has emerged as a promising strategy for constructing molecules rich in C(sp3)–stereocentres. However, achieving chemo- and enantioselective recombination of two prochiral alkyl radicals remains a substantial challenge. Here we synergistically repurpose a thiamine-dependent benzoylformate decarboxylase (PpBFD) with a photoinduced radical process, unlocking unnatural photobiocatalytic C(sp3)–C(sp3) bond formation. This system converts simple cinnamyl aldehydes into enantioenriched carboxylic acids bearing valuable β-, or β,γ-C(sp3)–stereocentres, a new-to-nature transformation that is difficult to achieve with conventional methods. Through directed evolution, we precisely control alkyl radicals to achieve stereoselective C(sp3)–C(sp3) bond formation (38 examples, up to 96% e.e. and up to 91:9 d.r.). This work demonstrates that the reshaping of a different class of thiamine-dependent enzymes can expand the repertoire of radical biocatalysis.
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Data availability
Data relating to the materials and methods, experimental procedures, mechanistic studies and computational calculations, HPLC spectra and NMR spectra are available in the Supplementary Information or from the authors on reasonable request. The atomic coordinates and structure factors for wild-type PpBFD and its variant have been deposited in the Protein Data Bank (http://www.rcsb.org) under accession codes 9V67 and 9V6F, respectively. Crystallographic data for the structures reported in this Article have been deposited at the Cambridge Crystallographic Data Centre and can be obtained free of charge under deposition nos. CCDC 2444979 (3a), 2494145 (3c) and 2494143 (5a). The coordinates of QM/MM and DFT calculations and configurations for MD simulations are available via GitHub at https://github.com/Computational-Chemistry-Data/QMMM-and-QM-coordinates/tree/main.
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Acknowledgements
We thank D. Ye, C. Duan and Z. Shi from NJU for sharing their equipments and chemical reagents. We thank Y. Zheng from NJFU for help with single-crystal X-ray diffraction experiments. We also thank the staff members at beamline BL19U1 of the Shanghai Synchrotron Radiation Facility for their help with data collection. We acknowledge financial support from the National Key Research and Development Program of China (2022YFA0913000 to X. Huang), the National Natural Science Foundation of China (22277053 to X. Huang and 225B100011 to Z.Z.), the Fundamental Research Funds for the Central Universities (KG202503, 0205/14380351 and 0205/14380346 to X. Huang), the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China (JYB2025XDXM507 to X. Huang), the New Cornerstone Science Foundation through an XPLORER PRIZE (to X. Huang), the Open Project of State Key Laboratory of Synergistic Chem-Bio Synthesis (sklscbs202509 to X. Huang) Northwest A&F University Start-up Funding (A2190025001 to X. Hou), Jiangsu Basic Research Center for Synthetic Biology Grant (BK20233003 to J.Z.) and Guangdong S&T Program (2024B1111160007 to J.Z.).
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Contributions
J.C. developed the catalysis. J.C. and Y.B. performed most of the biocatalytic experiments. Q.Z. and B.W. performed theoretical calculations. X. Hou and J.Z. contributed to protein crystal studies. Z.W., H.S., Z.X., B.C., Z.Z. and Y.Z. assisted with the synthetic and mechanistic experiments. X. Huang wrote the manuscript with input from all authors. X. Huang coordinated and conceived the project.
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Supplementary Figs. 1–32, Tables 1–28 and methods.
Supplementary Data 1
cif files of 3a.
Supplementary Data 2
cif files of 3c.
Supplementary Data 3
cif files of 5a.
Supplementary Data 4 (download ZIP )
Crystallographic_data of protein PpBFD.
Supplementary Data 5 (download ZIP )
Crystallographic_data of protein RE1Csp3.
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Chun, J., Bao, Y., Zhang, Q. et al. Enantioselective C(sp3)–C(sp3) bond formation by synergistic thiamine-dependent radical biocatalysis and photoredox catalysis. Nat Catal (2026). https://doi.org/10.1038/s41929-026-01515-w
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DOI: https://doi.org/10.1038/s41929-026-01515-w
