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White B, Dudding T. Catalytic Light-Driven Strategy for Transforming Oximes to Carbonyls. J Org Chem 2024; 89:4569-4578. [PMID: 38478895 DOI: 10.1021/acs.joc.3c02793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Oxime and carbonyl functional groups serve as powerful chemical hubs for constructing complex synthetic targets and valuable molecular scaffolds. In furthering this value, we report a photopromoted catalytic deoximation protocol for converting oximes and their derivatives to carbonyl functional groups. This strategic approach benefits from the use of renewable light energy input and ambient air conditions, in addition to demonstrating good substrate scope, functional group tolerance, and product yields. In offering, insights into these reactivity mechanistic studies are communicated, and the value of this protocol is further shown through one-pot operations.
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Affiliation(s)
- Brandon White
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2 S3A1, Canada
| | - Travis Dudding
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2 S3A1, Canada
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2
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Wang T, Zong YY, Feng WZ, Wu LZ, Liu Q. Visible-Light-Mediated Generation of Acyl Radicals from Triazine Esters. J Org Chem 2023; 88:12698-12708. [PMID: 37589746 DOI: 10.1021/acs.joc.3c01377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Acyl radicals are significant synthetic active species in organic synthesis. However, their generation via green and compatible methods remains challenging. Herein, we report an unprecedented visible-light-mediated approach for generating aryl acyl radicals from readily available triazine esters. This protocol with mild and redox-neutral conditions affords a diverse array of oxindoles attached to alcohol groups in a single operation. The recycling of leaving groups and a range of visible-light-mediated reactions using triazine ester as an acyl radical precursor demonstrate the synthetic potential of this methodology.
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Affiliation(s)
- Tao Wang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Yuan-Yuan Zong
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Wan-Zhong Feng
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Li-Zhu Wu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, The Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Qiang Liu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
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Joshi H, Paul D, Sathyamoorthi S. Oxidations of Alcohols, Aldehydes, and Diols Using NaBr and Selectfluor. J Org Chem 2023; 88:11240-11252. [PMID: 37490704 PMCID: PMC10804234 DOI: 10.1021/acs.joc.3c01307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
We present protocols for the oxidation of alcohols and aldehydes and for the oxidative cyclization of diols which use a combination of Selectfluor and NaBr. For most substrates, the optimal solvent system is a 1:1 mixture of CH3CN/H2O, but, in select cases, biphasic 1:1 mixtures of EtOAc/H2O or CH2Cl2/H2O are superior. This procedure is operationally simple, uses inexpensive and readily available reagents, and tolerates a variety of functional groups. Mechanistic studies suggest that the active oxidant is hypobromous acid, generated by the almost instantaneous oxidation of Br- by Selectfluor in an aqueous milieu.
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Affiliation(s)
- Harshit Joshi
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Debobrata Paul
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Shyam Sathyamoorthi
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
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Bezawada SA, Ušto N, Wilke C, Barnes-Flaspoler M, Jagan R, Bauer EB. Ferrocenophanium Stability and Catalysis. Molecules 2023; 28:molecules28062729. [PMID: 36985702 PMCID: PMC10058812 DOI: 10.3390/molecules28062729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 03/30/2023] Open
Abstract
Ferrocenium catalysis is a vibrant research area, and an increasing number of ferrocenium-catalyzed processes have been reported in the recent years. However, the ferrocenium cation is not very stable in solution, which may potentially hamper catalytic applications. In an effort to stabilize ferrocenium-type architectures by inserting a bridge between the cyclopentadienyl rings, we investigated two ferrocenophanium (or ansa-ferrocenium) cations with respect to their stability and catalytic activity in propargylic substitution reactions. One of the ferrocenophanium complexes was characterized by single crystal X-ray diffraction. Cyclic voltammetry experiments of the ferrocenophane parent compounds were performed in the absence and presence of alcohol nucleophiles, and the stability of the cations in solution was judged based on the reversibility of the electron transfer. The experiments revealed a moderate stabilizing effect of the bridge, albeit the effect is not very pronounced or straightforward. Catalytic propargylic substitution test reactions revealed decreased activity of the ferrocenophanium cations compared to the ferrocenium cation. It appears that the somewhat stabilized ferrocenophanium cations show decreased catalytic activity.
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Affiliation(s)
- Sai Anvesh Bezawada
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
| | - Neira Ušto
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
| | - Chloe Wilke
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
| | - Michael Barnes-Flaspoler
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
| | - Rajamoni Jagan
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
| | - Eike B Bauer
- Department of Chemistry and Biochemistry, University of Missouri, One University Boulevard, St. Louis, MO 63121, USA
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Song L, Zhou Y, Liang H, Li H, Lai Y, Yao H, Lin R, Tong R. Two Green Protocols for Halogenative Semipinacol Rearrangement. J Org Chem 2023; 88:504-512. [PMID: 36480595 DOI: 10.1021/acs.joc.2c02496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Semipinacol rearrangement is a special type of Wagner-Meerwein rearrangement that involves carbocation 1,2-rearrangement to provide carbonyl compounds with an α-quaternary carbon center. It has been strategically used for natural product synthesis and construction of highly congested quaternary carbons. Herein, we report a safe and green protocol that uses oxone/halide and Fenton bromide to achieve halogenative semipinacol rearrangement. The key feature of this method is the green in situ generation of reactive halogenating species from oxidation of halide with oxone or H2O2, which produces a nontoxic byproduct (potassium sulfate or water). Easy operation (insensitive to air and moisture) at room temperature without using special equipment adds additional advantage over previous methods.
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Affiliation(s)
- Liyan Song
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yiqin Zhou
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Hanbin Liang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Hongzuo Li
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yunrong Lai
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Hongliang Yao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, Guangdong 510275, China
| | - Ran Lin
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China.,Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, Guangdong 510275, China
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Efficient thiocyanation of phenols and anilines in the CeBr3 / H2O2 system. MENDELEEV COMMUNICATIONS 2023. [DOI: 10.1016/j.mencom.2023.01.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Zhao J, Luo Z, Liu Y, Xu J, Huang Z, Xiong W. Photochemical oxidation of alcohols to ketones or aldehydes using DMSO as an oxidant without activated agent. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.133208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wang J, Chen Y, Du W, Chen N, Fu K, He Q, Shao L. Green oxidative rearrangement of indoles using halide catalyst and hydrogen peroxide. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.133101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Weng Z, Wang L. Convenient thiocyanation of indoles in CeBr3/H2O2 system. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.154090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Liang L, Guo LD, Tong R. Achmatowicz Rearrangement-Inspired Development of Green Chemistry, Organic Methodology, and Total Synthesis of Natural Products. Acc Chem Res 2022; 55:2326-2340. [PMID: 35916456 DOI: 10.1021/acs.accounts.2c00358] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The six-membered heterocycles containing oxygen and nitrogen (tetrahydropyrans, pyrans, piperidines) are among the most common heterocyclic structures ubiquitously present in bioactive molecules such as carbohydrates, small-molecule drugs, and natural products. Chemical synthesis of fully functionalized pyrans and piperidines is a research theme of practical importance and scientific significance and, thus, has attracted continuous interest from synthetic chemists. Among the numerous synthetic approaches, Achmatowicz rearrangement (AchR) represents a general and unique strategy that uses biomass-derived furfuryl alcohols as the renewable starting material to obtain fully functionalized six-membered oxygen/nitrogen heterocycles, which provides golden opportunities for organic chemists to address various synthetic challenges.This Account summarizes our 10 years of work on exploiting AchR to address some challenges in organic synthesis ranging from green chemistry and organic methodology to the total synthesis of natural products. We enabled the sustainable and safe use of AchR in a small (academia) or large (industrial) scale by developing two generations of green approaches for AchR (oxone-halide and Fenton-halide), which largely eliminate the use of the most popular, but more toxic and expansive, NBS and m-CPBA. This triggered our intensive interest in developing new green chemistry for important organic reactions, in particular, halogenation/oxidation reactions involving reactive halogenating species with the aim of eliminating the use of commonly used toxic halogen agents such as elemental bromine, chlorine gas, and various N-haloamide reagents (NBS, NCS, and NIS). We successfully employed oxone-halide and Fenton-halide as green alternatives to several mechanistically related organic reactions including arene/alkene halogenation, oxidation or oxidative rearrangement of indoles, oxidation of alcohols/thioacetals, and oxidative halogenation of aldoximes for the in situ generation of nitrile oxide. These green reactions are expected to have a solid impact on the future of organic synthesis in academia and industries.We expanded the synthetic utility of AchR by exploring several new transformations of AchR products and developed a cascade reductive ring expansion, reductive deoxygenation/Heck-Matsuda arylation, palladium-catalyzed C-arylation, and regiodivergent [3 + 2] cycloaddition with 1,3-dicarbonyls. These methodologies offer a new avenue to fully functionalized six-membered heterocycles.The synthetic utility of AchR was demonstrated in our total synthesis of 28 natural products with a pyran/piperidine moiety. The AchR-based strategy endows the total synthesis with scalability, sustainability, and flexibility. The green and scalable approaches developed in our lab for AchR allow us to easily obtain decagrams of synthetically valuable pyrans and/or piperidines with low risk and low cost from biomass-derived furfuryl alcohol/aldehyde.
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