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Wackelin DJ, Mao R, Sicinski KM, Zhao Y, Das A, Chen K, Arnold FH. Enzymatic Assembly of Diverse Lactone Structures: An Intramolecular C-H Functionalization Strategy. J Am Chem Soc 2024; 146:1580-1587. [PMID: 38166100 PMCID: PMC11290351 DOI: 10.1021/jacs.3c11722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Lactones are cyclic esters with extensive applications in materials science, medicinal chemistry, and the food and perfume industries. Nature's strategy for the synthesis of many lactones found in natural products always relies on a single type of retrosynthetic strategy, a C-O bond disconnection. Here, we describe a set of laboratory-engineered enzymes that use a new-to-nature C-C bond-forming strategy to assemble diverse lactone structures. These engineered "carbene transferases" catalyze intramolecular carbene insertions into benzylic or allylic C-H bonds, which allow for the synthesis of lactones with different ring sizes and ring scaffolds from simple starting materials. Starting from a serine-ligated cytochrome P450 variant previously engineered for other carbene-transfer activities, directed evolution generated a variant P411-LAS-5247, which exhibits a high activity for constructing a five-membered ε-lactone, lactam, and cyclic ketone products (up to 5600 total turnovers (TTN) and >99% enantiomeric excess (ee)). Further engineering led to variants P411-LAS-5249 and P411-LAS-5264, which deliver six-membered δ-lactones and seven-membered ε-lactones, respectively, overcoming the thermodynamically unfavorable ring strain associated with these products compared to the γ-lactones. This new carbene-transfer activity was further extended to the synthesis of complex lactone scaffolds based on fused, bridged, and spiro rings. The enzymatic platform developed here complements natural biosynthetic strategies for lactone assembly and expands the structural diversity of lactones accessible through C-H functionalization.
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Affiliation(s)
- Daniel J. Wackelin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Runze Mao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Kathleen M. Sicinski
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Yutao Zhao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Present address: Department of Chemistry, The University of Chicago, Chicago, IL 60637, United States
| | - Anuvab Das
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Kai Chen
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Present address: Innovative Genomics Institute, University of California, Berkeley, CA 94720, United States
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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