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Recent Advances in Oxa-6π Electrocyclization Reactivity for the Synthesis of Privileged Natural Product Scaffolds. ORGANICS 2021. [DOI: 10.3390/org2040021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The stunning advances in understanding the reactivity and selectivity principles of asymmetric pericyclic reactions have had a profound impact on the synthetic planning of complex natural products. Indeed, electrocyclizations, cycloadditions, and sigmatropic rearrangements enable synthetic chemists to craft highly functionalized scaffolds that would not otherwise be possible with a similar atom-, step-, and redox-economy. In this review, selected examples from the last two decades of research (2003–2020) on tandem processes combining oxa-6π electrocyclic reactions are discussed in terms of reactivity challenges, inherent reversibility, and key structural bond formation in the assembly of natural products. A particular emphasis is given to the electrocyclic ring-closures in the tandem processes featuring Knoevenagel-type condensations, Diels–Alder cycloadditions, Stille couplings, and oxidative dearomatizations. The synthetic manifolds reviewed here illustrate how oxa-6π electrocyclizations are intimately linked to the construction of complex natural product scaffolds and have inspired a number of biomimetic syntheses in the laboratory.
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Chen P, Wu H, Li Y, Tang Y. Total syntheses of (+)-arisugacins F, G. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yao H, Song L, Liu Y, Tong R. Cascade Michael Addition/Cycloketalization of Cyclic 1,3-Dicarbonyl Compounds: Important Role of the Tethered Alcohol of α,β-Unsaturated Carbonyl Compounds on Reaction Rate and Regioselectivity. J Org Chem 2014; 79:8774-85. [DOI: 10.1021/jo501604e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Hongliang Yao
- Department
of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
| | - Liyan Song
- Department
of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
| | - Yuan Liu
- Department
of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
| | - Rongbiao Tong
- Department
of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
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Buchanan GS, Cole KP, Li G, Tang Y, You LF, Hsung RP. Constructing the Architecturally Distinctive ABD-Tricycle of Phomactin A through an Intramolecular Oxa-[3 + 3] Annulation Strategy. Tetrahedron 2011; 67:10105-10118. [PMID: 23750054 PMCID: PMC3676308 DOI: 10.1016/j.tet.2011.09.111] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Our efforts in constructing the ABD-ring of phomactin A through an intramolecular oxa-[3 + 3] annulation strategy is described. This struggle entailed finding a practical and efficient preparation of annulation precursor, and a realization of the unexpected competing regioisomeric pathway. The success entailed accessing the A-ring through Diels-Alder cycloaddition of Rawal's diene. Furthermore, the discovery that the regioisomers from the annulation existed as atropisomers with respect to the D-ring olefin and that they could be equilibrated to the desired ABD-tricycle, allowing large quantities of tricycle to be accessed.
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Affiliation(s)
- Grant S Buchanan
- Division of Pharmaceutical Sciences and Department of Chemistry, University of Wisconsin, Madison, WI 53705 USA
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Buchanan GS, Cole KP, Tang Y, Hsung RP. Total synthesis of (±)-phomactin A. Lessons learned from respecting a challenging structural topology. J Org Chem 2011; 76:7027-39. [PMID: 21819039 PMCID: PMC3163054 DOI: 10.1021/jo200936r] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Our struggles and ultimate success in achieving a total synthesis of phomactin A are described. Our strategy features an intramolecular oxa-[3 + 3] annulation to construct its unique ABD-tricyclic manifold. Although the synthesis would constitute a distinctly new approach with the 12-membered D-ring of phomactin A being assembled simultaneously with the 1-oxadecalin at an early stage, the ABD-tricycle represents a unique structural topology that would pose a number of unprecedented challenges. One challenge concerned elaborating this tricycle to have oxygenation at the proper carbon atoms. To overcome this, we would utilize a Kornblum-DeLaMare ring-opening of a peroxide bridge as well as a challenging late-stage 1,3-allylic alcohol transposition. Further, the structural intricacies of the ABD-tricycle were uncovered by a conformational analysis that would be critical for the C5a-homologation.
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Affiliation(s)
- Grant S. Buchanan
- Division of Pharmaceutical Sciences and Department of Chemistry University of Wisconsin, Madison, WI 53705
| | - Kevin P. Cole
- Chemical Product R&D, Eli Lilly and Company, Indianapolis, IN 46284
| | - Yu Tang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072 P. R. China
| | - Richard P. Hsung
- Division of Pharmaceutical Sciences and Department of Chemistry University of Wisconsin, Madison, WI 53705
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Al-Rashid ZF, Hsung RP. (+)-Arisugacin A--computational evidence of a dual binding site covalent inhibitor of acetylcholinesterase. Bioorg Med Chem Lett 2011; 21:2687-91. [PMID: 21216144 PMCID: PMC3082004 DOI: 10.1016/j.bmcl.2010.12.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 12/04/2010] [Accepted: 12/07/2010] [Indexed: 01/14/2023]
Abstract
A computation docking study of the highly potent, non-nitrogen containing, acetylcholinesterase inhibitor (+)-arisugacin A is presented. The model suggests that (+)-arisugacin A is a dual binding site covalent inhibitor of AChE. These findings are examined in the context of Alzheimer's disease-modifying therapeutic design. (+)-Arisugacin A's revealed mode of action is unique, and may serve as a basis for the development of AD therapeutics capable of treating the symptomatic aspects of AD, while being neuroprotective with long term efficacy.
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Affiliation(s)
- Ziyad F. Al-Rashid
- Alchemical Research, LLC, 426 Heckewelder Place, Bethlehem, Pennsylvania 18018, USA
| | - Richard P Hsung
- Division of Pharmaceutical Sciences and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53705, USA
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Krasnov VP, Demin AM, Levit GL, Grishakov AN, Sadretdinova LS, Ol’shevskaya VA, Glukhov IV, Kalinin VN, Charushin VN. Determination of enantiomeric purity of 1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes by HPLC on chiral stationary phases. Russ Chem Bull 2010. [DOI: 10.1007/s11172-008-0364-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
An enantioselective total synthesis of (+)-lepadin F is described. The synthetic sequence features an intermolecular aza-[3 + 3] annulation, homologation of a vinylogous amide via Eschenmoser's episulfide contraction, and a highly stereoselective hydrogenation essential for achieving the 1,3-anti relative stereochemistry at C2 and C8a.
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Affiliation(s)
- Gang Li
- Division of Pharmaceutical Sciences and Department of Chemistry, 777 Highland Avenue, University of Wisconsin, Madison, Wisconsin 53705, USA
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Wang Y, Fang DC, Liu RZ. Computational study of intermolecular formal oxa-[3+3] cycloaddition reactions. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2007.11.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kurdyumov AV, Lin N, Hsung RP, Gullickson GC, Cole KP, Sydorenko N, Swidorski JJ. A Lewis acid-catalyzed formal [3 + 3] cycloaddition of alpha,beta-unsaturated aldehydes with 4-hydroxy-2-pyrone, diketones, and vinylogous esters. Org Lett 2006; 8:191-3. [PMID: 16408872 DOI: 10.1021/ol0523042] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] A Lewis acid-catalyzed formal cycloaddition of alpha,beta-unsaturated aldehydes with 6-methyl-4-hydroxy-2-pyrone, 1,3-diketones, and vinylogous silyl esters is described here.
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Sunazuka T, Omura S. Total synthesis of alpha-pyrone meroterpenoids, novel bioactive microbial metabolites. Chem Rev 2006; 105:4559-80. [PMID: 16351054 DOI: 10.1021/cr040628i] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Toshiaki Sunazuka
- Kitasato Institute for Life Sciences, Kitasato University, and The Kitasato Institute, Shirokane, Minato-ku, Japan
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Liu H, Siegel DR, Danishefsky SJ. Studies Directed toward the Synthesis of Terreulactone A: Rapid Construction of the A, B, C Rings. Org Lett 2006; 8:423-5. [PMID: 16435850 DOI: 10.1021/ol052618p] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[structure: see text]. An efficient, rapid synthesis of the A, B, C rings of terreulactone A is described. Key steps in the synthesis include a diastereoselective benzylic acid rearrangement to create the desired quaternary center at C2 and a mild bromolactonization to assemble the lactonic ring A.
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Affiliation(s)
- Haibo Liu
- Department of Chemistry, Columbia University, Havemeyer Hall, New York, New York 10027, USA
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Sagar R, Singh P, Kumar R, Maulik PR, Shaw AK. Diastereoselective annulation of 4-hydroxypyran-2H-ones with enantiopure 2,3-dideoxy-α,β-unsaturated sugar aldehydes derived from respective glycals. Carbohydr Res 2005; 340:1287-300. [PMID: 15854598 DOI: 10.1016/j.carres.2005.02.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 02/18/2005] [Indexed: 11/17/2022]
Abstract
One-pot condensations of 4-hydroxypyran-2H-ones 1 and 2, respectively, with various enantiopure 2,3-dideoxy-alpha,beta-unsaturated carbohydrate enals in the presence of l-proline in EtOAc at room temperature generated pyrano-pyrones. It was observed that, while benzyl-protected carbohydrate enals on condensation with 1 or 2 under the above conditions produced an inseparable diastereomeric mixture in a ratio of 1:1, the acyl-protected carbohydrate enals on treatment with 1 or 2 under identical conditions yielded products with moderate to very high diastereoselectivity. A remarkable asymmetric induction was noticed from the C-4 stereogenic center of the acyl-protected carbohydrate enals. An almost complete diastereoselectivity was observed in those reactions that involved condensation of 1 with acetyl-protected enals 5 and 7. The reaction of 2 with 5 also proceeded diastereoselectively to furnish the corresponding annulated product. The reaction presumably took place by C-1,2-addition of the pyrone onto the iminium salt of the alpha,beta-unsaturated carbohydrate enal generated in situ, followed by beta-elimination and cyclization of the 1-oxatriene involving a 6pi-electron electrocyclic process to yield a 2H,5H-pyrano[3,2-c]pyran-5-one derivative.
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Affiliation(s)
- Ram Sagar
- Division of Medicinal and Process Chemistry, Central Drug Research Institute (CDRI), Lucknow 226001, India
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Jiang X, Ao L, Zhou C, Yang L, Zhang Q, Li H, Sun L, Wu X, Bai H, Zhao Y. Design, Synthesis, and Biological Evaluation of New Territrem B Analogues. Chem Biodivers 2005; 2:557-67. [PMID: 17192004 DOI: 10.1002/cbdv.200590036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Some 23 analogues of the potent acetylcholinesterase (AChE) inhibitor territrem B (1) were designed, synthesized, and tested for their biological activities. Some of the new synthetic derivatives exhibited IC50 values for AChE inhibition in the upper micromolar range. Molecular-modeling studies indicated that a planar conformation seems to be crucial for AChE inhibition. The two N-atoms of the piperazine moieties in 5o, 5p, and 5r might further enhance the inhibitory effects. The cytotoxicities of selected compounds against six human tumor cell lines were also determined.
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Affiliation(s)
- Xiangrui Jiang
- Department of Traditional Chinese Medicine and Natural Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, PR China
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Cole KP, Hsung RP. Unique structural topology and reactivities of the ABD tricycle in phomactin A. Chem Commun (Camb) 2005:5784-6. [PMID: 16307145 DOI: 10.1039/b511338e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stereoselective and transannular reactivities are described for the ABD tricyclic manifold of phomactin A that possesses a unique structural topology.
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Affiliation(s)
- Kevin P Cole
- Department of Chemistry, University of Minnesota, Minneapolis, 55455-0431, USA
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Hsung R, Kurdyumov A, Sydorenko N. A Formal [3 + 3] Cycloaddition Approach to Natural‐Product Synthesis. European J Org Chem 2004. [DOI: 10.1002/ejoc.200400567] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Richard P. Hsung
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Aleksey V. Kurdyumov
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Nadiya Sydorenko
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Hsung RP, Cole KP. The Total Synthesis of (-)-Arisugacin A. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s1874-6004(04)80007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Shen HC, Wang J, Cole KP, McLaughlin MJ, Morgan CD, Douglas CJ, Hsung RP, Coverdale HA, Gerasyuto AI, Hahn JM, Liu J, Sklenicka HM, Wei LL, Zehnder LR, Zificsak CA. A formal [3 + 3] cycloaddition reaction. Improved reactivity using alpha,beta-unsaturated iminium salts and evidence for reversibility of 6pi-electron electrocyclic ring closure of 1-oxatrienes. J Org Chem 2003; 68:1729-35. [PMID: 12608785 DOI: 10.1021/jo020688t] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A detailed account regarding a formal [3 + 3] cycloaddition method using 4-hydroxy-2-pyrones and 1,3-diketones is described here. This formal cycloaddition reaction or annulation reaction is synthetically useful for constructing 2H-pyranyl heterocycles. The usage of alpha,beta-unsaturated iminium salts is significant in controlling competing reaction pathways to give exclusively 2H-pyrans. Most significantly, experimental evidence is provided to support the mechanism of this reaction that involves a sequential Knoevenagel condensation and a reversible 6pi-electron electrocyclic ring-closure of 1-oxatrienes.
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Affiliation(s)
- Hong C Shen
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Chapter 6.4 Six-membered ring systems: With O and/or S atoms. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0959-6380(03)80018-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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