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Ju W, Wang X, Tian H, Gui J. Asymmetric Total Synthesis of Clionastatins A and B. J Am Chem Soc 2021; 143:13016-13021. [PMID: 34398601 DOI: 10.1021/jacs.1c07511] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Herein we report the first total synthesis of polychlorinated steroids clionastatins A and B, which was accomplished asymmetrically by means of a convergent, radical fragment coupling approach. Key features of the synthesis include an Ireland-Claisen rearrangement to introduce the C5 stereocenter (which was ultimately transferred to the C10 quaternary stereocenter of the clionastatins via a traceless stereochemical relay), a regioselective acyl radical conjugate addition to join the two fragments, an intramolecular Heck reaction to install the C10 quaternary stereocenter, and a diastereoselective olefin dichlorination to establish the synthetically challenging pseudoequatorial dichlorides. This work also enabled us to determine that the true structures of clionastatins A and B are in fact C14 epimers of the originally proposed structures.
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Affiliation(s)
- Wei Ju
- 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
| | - Xudong Wang
- 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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2
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Khatri HR, Bhattarai B, Kaplan W, Li Z, Curtis Long MJ, Aye Y, Nagorny P. Modular Total Synthesis and Cell-Based Anticancer Activity Evaluation of Ouabagenin and Other Cardiotonic Steroids with Varying Degrees of Oxygenation. J Am Chem Soc 2019; 141:4849-4860. [PMID: 30802047 DOI: 10.1021/jacs.8b12870] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A Cu(II)-catalyzed diastereoselective Michael/aldol cascade approach is used to accomplish concise total syntheses of cardiotonic steroids with varying degrees of oxygenation including cardenolides ouabagenin, sarmentologenin, 19-hydroxysarmentogenin, and 5- epi-panogenin. These syntheses enabled the subsequent structure activity relationship (SAR) studies on 37 synthetic and natural steroids to elucidate the effect of oxygenation, stereochemistry, C3-glycosylation, and C17-heterocyclic ring. Based on this parallel evaluation of synthetic and natural steroids and their derivatives, glycosylated steroids cannogenol-l-α-rhamnoside (79a), strophanthidol-l-α-rhamnoside (92), and digitoxigenin-l-α-rhamnoside (97) were identified as the most potent steroids demonstrating broad anticancer activity at 10-100 nM concentrations and selectivity (nontoxic at 3 μM against NIH-3T3, MEF, and developing fish embryos). Further analyses indicate that these molecules show a general mode of anticancer activity involving DNA-damage upregulation that subsequently induces apoptosis.
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Affiliation(s)
- Hem Raj Khatri
- Chemistry Department , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Bijay Bhattarai
- Chemistry Department , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Will Kaplan
- Chemistry Department , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Zhongzheng Li
- Department of Chemistry , Nankai University , Nankai 300071 , People's Republic of China
| | - Marcus John Curtis Long
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Yimon Aye
- Institute of Chemical Sciences and Engineering , École Polytechnique Fédérale de Lausanne , 1015 Lausanne , Switzerland.,Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Pavel Nagorny
- Chemistry Department , University of Michigan , Ann Arbor , Michigan 48109 , United States
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3
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Fan JH, Hu YJ, Guo Q, Li S, Zhao J, Li CC. Asymmetric synthesis of the tetracyclic core of bufogargarizin C by an intramolecular [5 + 2] cycloaddition. Org Chem Front 2019. [DOI: 10.1039/c8qo01089g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A concise asymmetric synthesis of the synthetically challenging 7/5/6/5-tetracyclic core of bufogargarizin C by a unique intramolecular [5 + 2] cycloaddition was reported.
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Affiliation(s)
- Jian-Hong Fan
- Institute of Chinese Medical Sciences
- University of Macau
- Macau
- China
- Shenzhen Grubbs Institute and Department of Chemistry
| | - Ya-Jian Hu
- Institute of Chinese Medical Sciences
- University of Macau
- Macau
- China
- Shenzhen Grubbs Institute and Department of Chemistry
| | - Qiang Guo
- Shenzhen Grubbs Institute and Department of Chemistry
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Shaoping Li
- Institute of Chinese Medical Sciences
- University of Macau
- Macau
- China
| | - Jing Zhao
- Institute of Chinese Medical Sciences
- University of Macau
- Macau
- China
| | - Chuang-Chuang Li
- Shenzhen Grubbs Institute and Department of Chemistry
- Southern University of Science and Technology
- Shenzhen 518055
- China
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4
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Michalak M, Michalak K, Wicha J. The synthesis of cardenolide and bufadienolide aglycones, and related steroids bearing a heterocyclic subunit. Nat Prod Rep 2017; 34:361-410. [PMID: 28378871 DOI: 10.1039/c6np00107f] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Covering: early studies through to March 2016Cardenolides and bufadienolides constitute an attractive class of biologically active steroid derivatives which have been used for the treatment of heart disease in traditional remedies as well as in modern medicinal therapy. Due to their application as therapeutic agents and their unique molecular structures, bearing unsaturated 5- or 6-membered lactones (or other heterocycles) attached to the steroid core, cardio-active steroids have received great attention, which has intensified during the last decade, in the synthetic organic community. Advances in the field of cross-coupling reactions have provided a powerful tool for the attachment of lactone subunits to the steroid core. This current review covers a methodological analysis of synthetic efforts to cardenolide and bufadienolide aglycones. Special emphasis is given to cross-coupling reactions applied for the attachment of lactone subunits at sterically very hindered positions of the steroid core. The carefully selected partial and total syntheses of representative cardio-active steroids will also be presented to exemplify recent achievements (improvements) in the field.
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Affiliation(s)
- Michał Michalak
- Institute of Organic Chemistry, Polish Academy of Sciences, ul. Marcina Kasprzaka 44/52, 01-224 Warsaw, Poland.
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5
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Kaplan W, Khatri HR, Nagorny P. Concise Enantioselective Total Synthesis of Cardiotonic Steroids 19-Hydroxysarmentogenin and Trewianin Aglycone. J Am Chem Soc 2016; 138:7194-8. [PMID: 27232585 PMCID: PMC5015484 DOI: 10.1021/jacs.6b04029] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The expedient and scalable approach to cardiotonic steroids carrying oxygenation at the C11- and C19-positions has been developed and applied to the total asymmetric synthesis of steroids 19-hydroxysarmentogenin and trewianin aglycone as well as to the assembly of the panogenin core. This new approach features enantioselective organocatalytic oxidation of an aldehyde, diastereoselective Cu(OTf)2-catalyzed Michael reaction/tandem aldol cyclizations, and one-pot reduction/transposition reactions allowing a rapid (7 linear steps) assembly of a functionalized cardenolide skeleton. The ability to quickly set this steroidal core with preinstalled functional handles and diversity elements eliminates the need for difficult downstream functionalizations and substantially improves the accessibility to the entire class of cardenolides and their derivatives for biological evaluation.
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Affiliation(s)
- Will Kaplan
- Chemistry Department, University of Michigan, Ann Arbor, MI 48109
| | - Hem Raj Khatri
- Chemistry Department, University of Michigan, Ann Arbor, MI 48109
| | - Pavel Nagorny
- Chemistry Department, University of Michigan, Ann Arbor, MI 48109
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6
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Cichowicz NR, Kaplan W, Khomutnyk Y, Bhattarai B, Sun Z, Nagorny P. Concise Enantioselective Synthesis of Oxygenated Steroids via Sequential Copper(II)-Catalyzed Michael Addition/Intramolecular Aldol Cyclization Reactions. J Am Chem Soc 2015; 137:14341-8. [PMID: 26491886 PMCID: PMC4651737 DOI: 10.1021/jacs.5b08528] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A new scalable enantioselective approach to functionalized oxygenated steroids is described. This strategy is based on chiral bis(oxazoline) copper(II) complex-catalyzed enantioselective and diastereoselective Michael reactions of cyclic ketoesters and enones to install vicinal quaternary and tertiary stereocenters. In addition, the utility of copper(II) salts as highly active catalysts for the Michael reactions of traditionally unreactive β,β'-enones and substituted β,β'-ketoesters that results in unprecedented Michael adducts containing vicinal all-carbon quaternary centers is also demonstrated. The Michael adducts subsequently undergo base-promoted diastereoselective aldol cascade reactions resulting in the natural or unnatural steroid skeletons. The experimental and computational studies suggest that the torsional strain effects arising from the presence of the Δ(5)-unsaturation are key controlling elements for the formation of the natural cardenolide scaffold. The described method enables expedient generation of polycyclic molecules including modified steroidal scaffolds as well as challenging-to-synthesize Hajos-Parrish and Wieland-Miescher ketones.
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Affiliation(s)
- Nathan R. Cichowicz
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
| | - Will Kaplan
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
| | - Yaroslav Khomutnyk
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
| | - Bijay Bhattarai
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
| | - Zhankui Sun
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
| | - Pavel Nagorny
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109
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7
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Renata H, Zhou Q, Dünstl G, Felding J, Merchant RR, Yeh CH, Baran PS. Development of a concise synthesis of ouabagenin and hydroxylated corticosteroid analogues. J Am Chem Soc 2015; 137:1330-40. [PMID: 25594682 PMCID: PMC4353025 DOI: 10.1021/ja512022r] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Indexed: 01/18/2023]
Abstract
The natural product ouabagenin is a complex cardiotonic steroid with a highly oxygenated skeleton. This full account describes the development of a concise synthesis of ouabagenin, including the evolution of synthetic strategy to access hydroxylation at the C19 position of a steroid skeleton. In addition, approaches to install the requisite butenolide moiety at the C17 position are discussed. Lastly, methodology developed in this synthesis has been applied in the generation of novel analogues of corticosteroid drugs bearing a hydroxyl group at the C19 position.
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Affiliation(s)
- Hans Renata
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Qianghui Zhou
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Georg Dünstl
- Front
End Innovation, LEO Pharma A/S, Industriparken 55, 2750 Ballerup, Denmark
| | - Jakob Felding
- Front
End Innovation, LEO Pharma A/S, Industriparken 55, 2750 Ballerup, Denmark
| | - Rohan R. Merchant
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Chien-Hung Yeh
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Phil S. Baran
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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8
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Mukai K, Urabe D, Kasuya S, Aoki N, Inoue M. A Convergent Total Synthesis of 19-Hydroxysarmentogenin. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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9
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Mukai K, Urabe D, Kasuya S, Aoki N, Inoue M. A Convergent Total Synthesis of 19-Hydroxysarmentogenin. Angew Chem Int Ed Engl 2013; 52:5300-4. [DOI: 10.1002/anie.201302067] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Indexed: 11/10/2022]
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10
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Heasley B. Chemical synthesis of the cardiotonic steroid glycosides and related natural products. Chemistry 2012; 18:3092-120. [PMID: 22354477 DOI: 10.1002/chem.201103733] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The active components from the extracts of Digitalis, cardiotonic steroid glycosides, have been ingested by humans for more than 200 years as a medicinal therapy for heart failure and abnormal heart rhythms. The positive inotropic activity of the cardiotonic steroids that mediates clinically useful physiological effects in patients has been attributed largely to a high affinity inhibitory interaction with the extracellular surface of the membrane-bound sodium pump (Na(+)/K(+)-ATPase). However, previously unrecognized intracellular signaling pathways continue to be uncovered. This Review examines both partial and de novo synthetic approaches to the medicinally important and structurally captivating cardenolide and bufadienolide steroid families, with an emphasis on the stereocontrolled construction of the pharmacophoric aglycone (genin) framework.
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Affiliation(s)
- Brian Heasley
- Scynexis, Inc. P. O. Box 12878, Research Triangle Park, NC 27709-2878, USA.
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11
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Ramachary DB, Vijayendar Reddy Y. A general approach to chiral building blocks via direct amino acid-catalyzed cascade three-component reductive alkylations: formal total synthesis of HIV-1 protease inhibitors, antibiotic agglomerins, brefeldin A, and (R)-gamma-hexanolide. J Org Chem 2010; 75:74-85. [PMID: 19954143 DOI: 10.1021/jo901799n] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multicatalysis cascade (MCC) process for the synthesis of highly substituted chiral building blocks (2-alkyl-CH-acids, 2-alkylcyclohexane-1,3-diones, 2-alkylcyclopentane-1,3-diones, and H-P ketone analogues) is presented based on the cascade three-component reductive alkylation's (TCRA) platform. Herein, we developed the high-yielding alkylation of a variety of CH-acids with (R)-glyceraldehyde acetonide/(S)-Garner aldehyde and Hantzsch ester through amino acid-catalyzed TCRA reaction without racemization at the alpha-position to carbonyl. Direct sequential combination of the L-proline-catalyzed TCRA reaction with other reactions like cascade alkylation/ketenization/esterification (A/K/E), alkylation/ketenization/esterification/alkylation (A/K/E/A), Brønsted acid-catalyzed cascade hydrolysis/lactonization/esterification (H/L/E), hydrolysis/esterification (H/E), hydrolysis/oxy-Michael/dehydration (H/OM/DH), and Robinson annulation (RA) of CH-acids, chiral aldehydes, Hantzsch ester, diazomethane, methyl vinyl ketone, various active olefins, and acetylenes furnished the highly functionalized chiral building blocks in good to high yields with excellent diastereoselectivities. In this context, many of the pharmaceutically applicable chiral building blocks were prepared via MCC reactions.
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Affiliation(s)
- Dhevalapally B Ramachary
- School of Chemistry, University of Hyderabad, Central University (PO), Hyderabad 500 046, India.
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12
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Reddy MS, Zhang H, Phoenix S, Deslongchamps P. Total synthesis of ouabagenin and ouabain. Chem Asian J 2009; 4:725-41. [PMID: 19294722 DOI: 10.1002/asia.200800429] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A full account of the total synthesis of ouabagenin and ouabain is described. A highly stereocontrolled anionic cycloaddition for the rapid construction of the basic steroid skeleton is a pivotal conversion for the whole strategy. A careful study was needed to establish the order and the sequence of functional group manipulations. Specific conformational features of the ouabain skeleton allowed us to overcome a few stereochemical problems. Degradation studies on ouabain provided an ultimate proof for a key intermediate, which is used as a relay. Late stage butenolide formation and glycosidation yielded ouabain.
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Affiliation(s)
- Maddi Sridhar Reddy
- Laboratoire de Synthèse Organique, Département de Chimie, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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13
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Abstract
Due to their high profile biological activity, the steroids are among the most important secondary metabolites. A review of literature on the synthesis of pentacyclic steroids is presented.
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Affiliation(s)
- Malika Ibrahim-Ouali
- Institut des Sciences Moléculaires de Marseille UMR 6263 CNRS, Université d'Aix Marseille III, Faculté des Sciences et Techniques de Saint Jérôme, Marseille Cedex 20, France.
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14
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Zhang H, Sridhar Reddy M, Phoenix S, Deslongchamps P. Total synthesis of ouabagenin and ouabain. Angew Chem Int Ed Engl 2008; 47:1272-5. [PMID: 18183567 DOI: 10.1002/anie.200704959] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hongxing Zhang
- Laboratoire de synthèse organique Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
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15
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Zhang H, Sridhar Reddy M, Phoenix S, Deslongchamps P. Total Synthesis of Ouabagenin and Ouabain. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704959] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Ramachary DB, Kishor M. Organocatalytic sequential one-pot double cascade asymmetric synthesis of Wieland-Miescher ketone analogues from a Knoevenagel/hydrogenation/Robinson annulation sequence: scope and applications of organocatalytic biomimetic reductions. J Org Chem 2007; 72:5056-68. [PMID: 17552564 DOI: 10.1021/jo070277i] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A practical and novel organocatalytic chemo- and enantioselective process for the cascade synthesis of highly substituted 2-alkyl-cyclohexane-1,3-diones and Wieland-Miescher (W-M) ketone analogs is presented via reductive alkylation as a key step. First time, we developed the one-step alkylation of dimedone and 1,3-cyclohexanedione with aldehydes and Hantzsch ester through an organocatalytic reductive alkylation strategy. Direct combination of l-proline-catalyzed cascade Knoevenagel/hydrogenation and cascade Robinson annulation of CH acids (dimedone and 1,3-cyclohexanedione), aldehydes, Hantzsch ester, and methyl vinyl ketone furnished the highly functionalized W-M ketone analogues in good to high yields and with excellent enantioselectivities. Many of the reductive alkylation products show a direct application in pharmaceutical chemistry.
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Affiliation(s)
- Dhevalapally B Ramachary
- School of Chemistry, University of Hyderabad, Central University (PO), Hyderabad 500 046, India.
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17
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Ramachandran SA, Kharul RK, Lepage O, Marque S, Soucy P, Jacques F, Chênevert R, Deslongchamps P. Synthetic Studies toward Highly Functionalized 5β-Lanosterol Derivatives: A Versatile Approach Utilizing Anionic Cycloaddition. J Org Chem 2006; 71:6149-56. [PMID: 16872199 DOI: 10.1021/jo0608725] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stereoselective synthesis of the potentially biologically valuable 5beta-lanosteroidal-type backbone was achieved via anionic cycloaddition. Synthesis of the two new bicyclic Nazarov intermediates 14 and 40 and their cycloaddition with chiral cyclohexenone 25 and further functional group manipulations resulted in highly functionalized tetracyclic intermediates 28 and 44. These synthetic intermediates could lead to the total synthesis of new lanosterol-based inhibitors.
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Affiliation(s)
- Sreekanth A Ramachandran
- Laboratoire de Synthèse Organique, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada, and Département de Chimie, Faculté des Sciences et de Génie Université Laval, Québec G1K 7P4, Canada
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18
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Affiliation(s)
- Rita Skoda-Földes
- Department of Organic Chemistry and Research Group for Petrochemistry of the Hungarian Academy of Sciences, University of Veszprém, Egyetem u. 8., P.O. Box 158, H-8200 Veszprém, Hungary.
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19
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Abstract
Several novel hydroxylated cis-decalin derivatives, potential intermediates for the synthesis of the AB ring system of the important cardiotonic steroid ouabain, have been synthesized from commercially available starting materials. The first step in the preparation of these highly functionalized intermediates is a Robinson annulation of the beta-keto ester 6 and the 4-silyl-3-buten-2-one 5 to furnish the octalone 4 with good diastereoselectivity in fair yield (due to competition with a novel silicon-to-carbon phenyl migration). Reduction of the epoxy alcohol 3 (derived from 4 in two high-yielding steps) with LiAlH(4) gave a mixture of the desired triol 11 along with the product of an unusual reductive opening at the tertiary carbon, namely the triol 12. A plausible mechanism for this unusual reduction is presented as are possible methods for avoiding it. In particular, reduction of the corrresponding epoxy ketone 15 with aluminum amalgam proceeded in good yield to give the hydroxy ketone 16. Also reduction of the epoxide ester having the inverted stereochemistry at C3 afforded the desired tertiary alcohol 33 in good yield. Another approach using the beta,gamma-unsaturated ketal 38 permitted the formation of the tertiary alcohol 40. Fleming oxidation of the related, very functionalized silane 39 afforded the desired 1beta-alcohol 41 in fair yield. Finally a novel rearrangement was observed when the epoxy alcohol 24 was treated with DIBAL to effect loss of the angular hydroxymethyl group to produce the tetrasubstitued alkene 29 in high yield.
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Affiliation(s)
- Michael E Jung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095-1569, USA.
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20
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Yang Z, Shannon D, Truong VL, Deslongchamps P. Studies directed toward asymmetric synthesis of cardioactive steroids via anionic polycyclization. Org Lett 2002; 4:4693-6. [PMID: 12489963 DOI: 10.1021/ol027125o] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] The use of anionic polycyclization (AP) in constructing the steroidal backbone of cardenolides was investigated. The reaction of 2-carbomethoxy-2-cyclohexenone I with the enolate of Nazarov reagent II gave, after decarboxylation and aldol condensation, steroid III with control of stereochemistry.
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Affiliation(s)
- Zhixiang Yang
- Laboratoire de synthèse organique, Institut de pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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21
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Nörret M, Sherburn MS. The Zipper-Mode Domino Intramolecular Diels-Alder Reaction: A New 0→ABCD Strategy for Steroids and Related Compounds. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20011105)113:21<4198::aid-ange4198>3.0.co;2-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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23
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Couturier M, Dory YL, Fortin D, Rouillard A, Deslongchamps P. Ab initio and semiempirical corroboration of the observed stereoselectivity in the transannular Diels-Alder reaction leading to steroids. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00600-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Overman LE, Rucker PV. Enantioselective synthesis of cardenolide precursors using an intramolecular Heck reaction. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)00859-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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25
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Hynes J, Overman LE, Nasser T, Rucker PV. Intramolecular Heck cyclization of α-sulfenyl enol triflates. Asymmetric synthesis of a pentacyclic cardenolide precursor having functionality at C-11. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)00860-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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27
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