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Abstract
Natural products are constructed by organisms in impressive ways through various highly selective enzyme-catalyzed chemical reactions. Over the past century, there has been considerable interest in understanding and emulating the underlying biosynthetic logic for the target molecule. The successful implementation of a biomimetic strategy usually has some uniquely valuable benefits over other abiotic routes in total synthesis by (1) corroborating the chemical feasibility of a given biogenetic hypothesis and further unraveling some insightful implications for future biosynthetic studies and (2) providing remarkably more concise access to not only the original synthetic target but also diversified biogenetically related congeners, which may result in either the structural reassignment of previously disclosed natural products or the anticipation of undiscovered natural products. However, for the devised essential biomimetic transformation, fine-tuning the optimization of the substrates and the reaction conditions can sometimes be painstakingly challenging. Turning to nature for inspiration can provide additional impetus for methodological innovations.Previously used as oral veterinary drugs, lankacidins have potential as next-generation antibiotics to tackle the problems caused by multidrug-resistant bacteria with novel modes of action (MoAs). The hypersensitive and densely functionalized lactonic core within this family of macrocyclic polyketides poses a formidable challenge for chemical total synthesis and derivatization. In this account, we summarized the evolution of a unified biomimetic approach toward 10 lankacidin antibiotics and their linear biosynthetic intermediates in the longest linear 7-12 steps from readily available starting materials. Our endeavor commenced with an intermolecular bioinspired amido sulfone-based Mannich reaction approach to assemble 2 advanced fragments under mild biphasic organocatalytic conditions. It successfully gave rise to stereodivergent access to 4 C2/C18-isomeric lankacyclinols but failed to efficiently deliver lactone-containing congeners through Stille macrocyclization. Facilitated by the thermolysis chemistry of N,O-acetal to generate the requisite N-acyl-1-azahexatriene species, we realized the projected Mannich macrocyclization and eight macrocyclic lankacidins can be produced by orchestrated desilylative manipulations. In this process, we were able to perform structural reassignments of isolankacidinol (7 to 50) and isolankacyclinol (104 to 83) and, for the first time, elucidate the natural occurrence of 2,18-bis-epi-lankacyclinol (84). Moreover, the inability of the current biomimetic route to cofurnish the reported structure of 2,18-seco-lankacidinol A (15) triggered a proposed structural revision that is rooted in reconsidered biogenesis and was confirmed by a divergent synthesis that enabled us to identify the correct isomer (116). Finally, the modular, diversity-oriented design also provided streamlined entries to acyclic 2,18-seco-lankacidinol B (120) and the biosynthetic intermediate LC-KA05 (17) together with its C7-O-deacetylated congeners in all C4/C5-stereochemical variations (18, 127-129), culminating in a need for structural revision to the six-membered lactonic segment in LC-KA05-2. The selection and execution of biomimetic strategies in lankacidin total synthesis give rise to all the previously mentioned advantages at the current stage. The modular-based, late-stage diversified complex construction offers an exceptionally high level of synthetic flexibility for future synthetic forays toward newly isolated or chemically modified congeners within the lankacidin family.
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Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, PR China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, PR China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, PR China
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Ning Y, Tian H, Gui J. Biogenesis-Guided Synthesis and Structural Revision of Sarocladione Enabled by Ruthenium-Catalyzed Endoperoxide Fragmentation. Angew Chem Int Ed Engl 2021; 60:11222-11226. [PMID: 33682234 DOI: 10.1002/anie.202101451] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/21/2021] [Indexed: 11/11/2022]
Abstract
Sarocladione is the first 5,10:8,9-diseco-steroid with a 14-membered macrocyclic diketone framework to have been isolated from a natural source. Herein we report a biomimetic synthesis of sarocladione in only two or seven steps from inexpensive, commercially available ergosterol. The key feature of this synthesis was a novel ruthenium-catalyzed endoperoxide fragmentation, which transformed various saturated endoperoxides into olefinic diketones by cleavage of two C-C bonds. This synthesis allowed us to unambiguously determine the structure of sarocladione and provided experimental support for its revised biosynthetic origin. This work also vividly demonstrates that consideration of the biogenesis is a powerful tool for elucidating the structures of natural products.
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Affiliation(s)
- Yuhan Ning
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Hailong Tian
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Jinghan Gui
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
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Ning Y, Tian H, Gui J. Biogenesis‐Guided Synthesis and Structural Revision of Sarocladione Enabled by Ruthenium‐Catalyzed Endoperoxide Fragmentation. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yuhan Ning
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Hailong Tian
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Jinghan Gui
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
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Zheng K, Hong R. Total synthesis of LC-KA05, the proposed structure of LC-KA05-2, and 2,18-seco-lankacidinol B: A quest to revisit lankacidin biosynthesis. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Cai L, Seiple IB, Li Q. Modular Chemical Synthesis of Streptogramin and Lankacidin Antibiotics. Acc Chem Res 2021; 54:1891-1908. [PMID: 33792282 DOI: 10.1021/acs.accounts.0c00894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Continued, rapid development of antimicrobial resistance has become worldwide health crisis and a burden on the global economy. Decisive and comprehensive action is required to slow down the spread of antibiotic resistance, including increased investment in antibiotic discovery, sustainable policies that provide returns on investment for newly launched antibiotics, and public education to reduce the overusage of antibiotics, especially in livestock and agriculture. Without significant changes in the current antibiotic pipeline, we are in danger of entering a post-antibiotic era.In this Account, we summarize our recent efforts to develop next-generation streptogramin and lankacidin antibiotics that overcome bacterial resistance by means of modular chemical synthesis. First, we describe our highly modular, scalable route to four natural group A streptogramins antibiotics in 6-8 steps from seven simple chemical building blocks. We next describe the application of this route to the synthesis of a novel library of streptogramin antibiotics informed by in vitro and in vivo biological evaluation and high-resolution cryo-electron microscopy. One lead compound showed excellent inhibitory activity in vitro and in vivo against a longstanding streptogramin-resistance mechanism, virginiamycin acetyltransferase. Our results demonstrate that the combination of rational design and modular chemical synthesis can revitalize classes of antibiotics that are limited by naturally arising resistance mechanisms.Second, we recount our modular approaches toward lankacidin antibiotics. Lankacidins are a group of polyketide natural products with activity against several strains of Gram-positive bacteria but have not been deployed as therapeutics due to their chemical instability. We describe a route to several diastereomers of 2,18-seco-lankacidinol B in a linear sequence of ≤8 steps from simple building blocks, resulting in a revision of the C4 stereochemistry. We next detail our modular synthesis of several diastereoisomers of iso-lankacidinol that resulted in the structural reassignment of this natural product. These structural revisions raise interesting questions about the biosynthetic origin of lankacidins, all of which possessed uniform stereochemistry prior to these findings. Finally, we summarize the ability of several iso- and seco-lankacidins to inhibit the growth of bacteria and to inhibit translation in vitro, providing important insights into structure-function relationships for the class.
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Affiliation(s)
- Lingchao Cai
- Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing Forestry University, Nanjing 210037, Jiangsu China
| | - Ian B. Seiple
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California 94158, United States
| | - Qi Li
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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Wei S, Bao X, Nawaz S, Qu J, Wang B. Identification of a tartrate-based modular guanidine towards highly asymmetric Michael addition of 3-aminooxindoles to nitroolefins. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2020.152741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Zheng K, Shen D, Zhang B, Hong R. Stereodivergent Synthesis of Lankacyclinol and Its C2/C18-Congeners Enabled by a Bioinspired Mannich Reaction. J Org Chem 2020; 86:10991-11005. [DOI: 10.1021/acs.joc.0c02443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China
| | - Defeng Shen
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China
| | - Bingbing Zhang
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, People’s Republic of China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China
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Zheng K, Shen D, Zhang B, Hong R. Landscape of Lankacidin Biomimetic Synthesis: Structural Revisions and Biogenetic Implications. J Org Chem 2020; 85:13818-13836. [PMID: 32985194 DOI: 10.1021/acs.joc.0c01930] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this report, a unified biomimetic approach to all known macrocyclic lankacidins is presented. By taking advantage of the thermolysis of N,O-acetal to generate the requisite N-acyl-1-azahexatriene species, we eventually realized the biomimetic Mannich macrocyclization, from which all of the macrocyclic lankacidins can be conquered by orchestrated desilylation. The reassignments of the reported structures of isolankacidinol (7 to 10) and the discovery of a recently isolated "lankacyclinol" found to be in fact 2,18-bis-epi-lankacyclinol (72) unraveled the previously underappreciated chemical diversity exhibited by the enzymatic macrocyclization. In addition, the facile elimination/decarboxylation/protonation process for the depletion of C1 under basic conditions resembling a physiological environment may implicate more undiscovered natural products with variable C2/C18 stereochemistries (i.e., 62, 73, and 75). The notable aspect provided by a biomimetic strategy is significantly reducing the step count compared with the two previous entries to macrocyclic lankacidins.
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Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Defeng Shen
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Bingbing Zhang
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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Abstract
Lankacidins are a class of polyketide natural products isolated from Streptomyces spp. that show promising antimicrobial activity. Owing to their complex molecular architectures and chemical instability, structural assignment and derivatization of lankacidins are challenging tasks. Herein we describe three fully synthetic approaches to lankacidins that enable access to new structural variability within the class. We use these routes to systematically generate stereochemical derivatives of both cyclic and acyclic lankacidins. Additionally, we access a new series of lankacidins bearing a methyl group at the C4 position, a modification intended to increase chemical stability. In the course of this work, we discovered that the reported structures for two natural products of the lankacidin class were incorrect, and we determine the correct structures of 2,18-seco-lankacidinol B and iso-lankacidinol. We also evaluate the ability of several iso- and seco-lankacidins to inhibit the growth of bacteria and to inhibit translation in vitro. This work grants insight into the rich chemical complexity of this class of antibiotics and provides an avenue for further structural derivatization.
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Affiliation(s)
- Lingchao Cai
- Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jinagsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing Forestry University, Nanjing, 210037 Jiangsu, China
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Yanmin Yao
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Seul Ki Yeon
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Ian B Seiple
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
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