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Wan Y, Ramírez E, Ford A, Zhang HK, Norton JR, Li G. Cooperative Fe/Co-Catalyzed Remote Desaturation for the Synthesis of Unsaturated Amide Derivatives. J Am Chem Soc 2024; 146:4985-4992. [PMID: 38320266 DOI: 10.1021/jacs.3c14481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Unsaturated amides represent common functional groups found in natural products and bioactive molecules and serve as versatile synthetic building blocks. Here, we report an iron(II)/cobalt(II) dual catalytic system for the syntheses of distally unsaturated amide derivatives. The transformation proceeds through an iron nitrenoid-mediated 1,5-hydrogen atom transfer (1,5-HAT) mechanism. Subsequently, the radical intermediate undergoes hydrogen atom abstraction from vicinal methylene by a cobaloxime catalyst, efficiently yielding β,γ- or γ,δ-unsaturated amide derivatives under mild conditions. The efficiency of Co-mediated HAT can be tuned by varying different auxiliaries, highlighting the generality of this protocol. Remarkably, this desaturation protocol is also amenable to practical scalability, enabling the synthesis of unsaturated carbamates and ureas, which can be readily converted into various valuable molecules.
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Affiliation(s)
- Yanjun Wan
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Emmanuel Ramírez
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
| | - Ayzia Ford
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
| | - Harriet K Zhang
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Jack R Norton
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Gang Li
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
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Gao S, Das A, Alfonzo E, Sicinski KM, Rieger D, Arnold FH. Enzymatic Nitrogen Incorporation Using Hydroxylamine. J Am Chem Soc 2023; 145:20196-20201. [PMID: 37671894 PMCID: PMC10560455 DOI: 10.1021/jacs.3c08053] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Hydroxylamine-derived reagents have enabled versatile nitrene transfer reactions for introducing nitrogen-containing functionalities in small-molecule catalysis, as well as biocatalysis. These reagents, however, result in a poor atom economy and stoichiometric organic waste. Activating hydroxylamine (NH2OH) for nitrene transfer offers a low-cost and sustainable route to amine synthesis, since water is the sole byproduct. Despite its presence in nature, hydroxylamine is not known to be used for enzymatic nitrogen incorporation in biosynthesis. Here, we report an engineered heme enzyme that can utilize hydroxylammonium chloride, an inexpensive commodity chemical, for nitrene transfer. Directed evolution of Pyrobaculum arsenaticum protoglobin generated efficient enzymes for benzylic C-H primary amination and styrene aminohydroxylation. Mechanistic studies supported a stepwise radical pathway involving rate-limiting hydrogen atom transfer. This unprecedented activity is a useful addition to the "nitrene transferase" repertoire and hints at possible future discovery of natural enzymes that use hydroxylamine for amination chemistry.
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Affiliation(s)
- Shilong Gao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Anuvab Das
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Edwin Alfonzo
- 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
| | - Dominic Rieger
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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