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Investigation of Grignard Reagent as an Advanced Base for Aza-Claisen Rearrangement. Molecules 2019; 24:molecules24244597. [PMID: 31888158 PMCID: PMC6943632 DOI: 10.3390/molecules24244597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/09/2019] [Accepted: 12/12/2019] [Indexed: 11/16/2022] Open
Abstract
Employing iPrMgCl as an advanced base instead of lithium hexamethyldisilazane (LHMDS) resulted in dramatic improvements in aza-Claisen rearrangement. This advance is considered responsible for the increased bulkiness of the alkoxide moiety (including magnesium cation and ligands), followed by a resultant conformational change of the transition state. To support this hypothesis, various substrates of aza-Claisen rearrangement were prepared and screened. In addition, a molecular dynamic simulation study was performed to investigate and compare the structural stability of reaction intermediates.
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Moon H, Yoon H, Lim C, Jang J, Yi JJ, Lee JK, Lee J, Na Y, Son WS, Kim SH, Suh YG. Asymmetric Synthesis of (-)-6-Desmethyl-Fluvirucinine A₁ via Conformationally-Controlled Diastereoselective Lactam-Ring Expansions. MOLECULES (BASEL, SWITZERLAND) 2018; 23:molecules23092351. [PMID: 30223428 PMCID: PMC6225218 DOI: 10.3390/molecules23092351] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 09/08/2018] [Accepted: 09/10/2018] [Indexed: 11/16/2022]
Abstract
The versatile synthesis of (−)-6-desmethyl-fluvirucinine A1 was accomplished at a 24% overall yield through a thirteen-step process from a known vinylpiperidine. The key part involved the elaboration of the distal stereocenters and a macrolactam skeleton via conformationally-induced diastereocontrol and the iterative aza-Claisen rearrangements of lactam precursors.
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Affiliation(s)
- Hyunyoung Moon
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Hojong Yoon
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Changjin Lim
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Jaebong Jang
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Jong-Jae Yi
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
| | - Jae Kyun Lee
- Center for Neuro-Medicine, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
| | - Jeeyeon Lee
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Younghwa Na
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
| | - Woo Sung Son
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
| | - Seok-Ho Kim
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
| | - Young-Ger Suh
- Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, 120 Haeryong-ro, Pocheon 11160, Gyeonggi-do, Korea.
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
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Suh YG, Lim C, Sim J, Lee JK, Surh YJ, Paek SM. Construction of the Azacyclic Core of Tabernaemontanine-Related Alkaloids via Tandem Reformatsky-Aza-Claisen Rearrangement. J Org Chem 2017; 82:1464-1470. [PMID: 28051867 DOI: 10.1021/acs.joc.6b02648] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A divergent synthetic methodology for a tabernaemontanine-related alkaloid was developed. The synthetic route features practical improvements in the Pictet-Spengler cyclization for the tetrahydro-β-carboline intermediate and an unprecedented tandem Reformatsky-aza-Claisen rearrangement to create the core carbon skeleton and stereochemistries of tabernaemontanine-related alkaloids.
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Affiliation(s)
- Young-Ger Suh
- College of Pharmacy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Changjin Lim
- College of Pharmacy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Jaehoon Sim
- College of Pharmacy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Jae Kyun Lee
- Neuro-Medicine Center, Korea Institute of Science and Technology , P.O. Box 131, Seoul 130-650, Republic of Korea
| | - Young-Joon Surh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Seung-Mann Paek
- College of Pharmacy, Research Institute of Pharmaceutical Science, Gyeongsang National University , Jinju daero, Jinju 660-751, Republic of Korea
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DeLuca RJ, Sigman MS. The palladium-catalyzed anti-Markovnikov hydroalkylation of allylic alcohol derivatives. Org Lett 2013; 15:92-5. [PMID: 23252845 PMCID: PMC3539300 DOI: 10.1021/ol303129p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A palladium-catalyzed hydroalkylation reaction of protected allylic alcohols using alkylzinc bromide reagents is reported. This account includes numerous allylic, homoallylic, and bishomoallylic alcohol derivatives, all with a uniform selectivity of >20:1 for the anti-Markovnikov product. The reaction features the ability to deliver enantiomerically enriched alcohols in unfunctionalized regions, which results from the catalyst avoiding β-hydride elimination at the allylic position.
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Affiliation(s)
- Ryan J. DeLuca
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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5
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Mohr JT, Krout MR, Stoltz BM. Natural products as inspiration for the development of asymmetric catalysis. Nature 2008; 455:323-32. [PMID: 18800131 PMCID: PMC2562237 DOI: 10.1038/nature07370] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biologically active natural products often contain particularly challenging structural features and functionalities in terms of synthesis. Perhaps the greatest difficulties are those caused by issues of stereochemistry. A useful strategy for synthesizing such molecules is to devise methods of bond formation that provide opportunities for using enantioselective catalysis. In using this tactic, the desire for a particular target structure ultimately drives the development of catalytic methods. New enantioselective catalytic methods contribute to a greater fundamental understanding of how bonds can be constructed and lead to valuable synthetic technologies that are useful for a variety of applications.
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Affiliation(s)
| | | | - Brian M. Stoltz
- The Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Boulevard, MC 164-30, Pasadena, CA 91125 (USA)
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Godenschwager P, Collum DB. Lithium hexamethyldisilazide-mediated enolizations: influence of triethylamine on E/Z selectivities and enolate reactivities. J Am Chem Soc 2008; 130:8726-32. [PMID: 18557616 PMCID: PMC3021125 DOI: 10.1021/ja800250q] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lithium hexamethyldisilazide (LiHMDS) in triethylamine (Et 3N)/toluene is shown to enolize acyclic ketones and esters rapidly and with high E/ Z selectivity. Mechanistic studies reveal a dimer-based mechanism consistent with previous studies of LiHMDS/Et 3N. E/ Z equilibration occurs when <2.0 equiv of LiHMDS are used. Studies of the aldol condensation and Ireland-Claisen rearrangement of the resulting Et 3N-solvated enolates show higher and often complementary diastereoselectivities when compared with analogous reactions in THF. The Et 3N-solvated enolates also display a marked (20-fold) acceleration of the Ireland-Claisen rearrangement with evidence of autocatalysis. A possible importance of amine-solvated enolates is discussed.
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Affiliation(s)
- Peter Godenschwager
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301
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