1
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Zhu HT, Liang CM, Li TY, Li LY, Zhang RL, Wang JN, Qi RQ, Zhang JM, Yang RH, Yang YQ, Zhou AX, Jin X, Zhou NN. Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of ( E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[ cd]azulenes. J Org Chem 2023; 88:3409-3423. [PMID: 36847758 DOI: 10.1021/acs.joc.2c02247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
A one-pot step-economic tandem process involving (5 + 2)-cycloaddition and Nazarov cyclization reactions has been reported for the facile synthesis of indanone-fused benzo[cd]azulenes from (E)-2-arylidene-3-hydroxyindanones and conjugated eneynes. This highly regio- and stereoselective bisannulation reaction is enabled by dual silver and Brønsted acid catalysis and opens up a new avenue for the construction of important bicyclo[5.3.0]decane skeletons.
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Affiliation(s)
- Hai-Tao Zhu
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Chun-Miao Liang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Ting-Yan Li
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Lin-Yan Li
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Rui-Ling Zhang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Jun-Na Wang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Rui-Qing Qi
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Jia-Min Zhang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Ruo-Han Yang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - Yin-Qi Yang
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
| | - An-Xi Zhou
- Key Laboratory of Applied Organic Chemistry, Higher Institutions of Jiangxi Province, Shangrao Normal University, Shangrao 334000, China
| | - Xiaojie Jin
- Gansu University Key Laboratory for Molecular Medicine & Chinese Medicine Prevention and Treatment of Major Diseases, Gansu University of Chinese Medicine, Lanzhou 730000, China
| | - Ni-Ni Zhou
- College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji 721013, China
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2
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Boron-tethered oxidopyrylium-based [5 + 2] cycloadditions. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.154094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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3
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Rokey SN, Simanis JA, Law CM, Pohani S, Willens Behrends S, Bulandr JJ, Ferrence GM, Goodell JR, Andrew Mitchell T. Intramolecular asymmetric oxidopyrylium-based [5 + 2] cycloadditions. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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4
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Fuhr KN, Hirsch DR, Murelli RP, Brenner-Moyer SE. Catalytic Enantioselective Intermolecular [5 + 2] Dipolar Cycloadditions of a 3-Hydroxy-4-pyrone-Derived Oxidopyrylium Ylide. Org Lett 2017; 19:6356-6359. [PMID: 29148809 PMCID: PMC5831127 DOI: 10.1021/acs.orglett.7b03196] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The first catalytic enantioselective [5 + 2] dipolar cycloaddition of a 3-hydroxy-4-pyrone-derived oxidopyrylium ylide is described. These studies leveraged the recently recognized ability of oxidopyrylium dimers to serve as the source of ylide, which was found to be key to increasing yields and achieving enantiomeric excesses up to 99%. General reaction conditions were identified for an array of α,β-unsaturated aldehyde dipolarophiles. Reaction products possess four stereocenters, and subsequent reduction introduced a fifth contiguous stereocenter with total stereocontrol.
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Affiliation(s)
- Katherine N. Fuhr
- Department of Chemistry, Rutgers University, Newark, New Jersey, USA 07102
| | - Danielle R. Hirsch
- Department of Chemistry, Brooklyn College, The City University of New York, Brooklyn, New York, USA 11210
- PhD Program in Chemistry, The Graduate Center, The City University of New York, New York, NY, USA 10016
| | - Ryan P. Murelli
- Department of Chemistry, Brooklyn College, The City University of New York, Brooklyn, New York, USA 11210
- PhD Program in Chemistry, The Graduate Center, The City University of New York, New York, NY, USA 10016
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5
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Yeung C, Ziegler RE, Porco JA, Jacobsen EN. Thiourea-catalyzed enantioselective addition of indoles to pyrones: alkaloid cores with quaternary carbons. J Am Chem Soc 2014; 136:13614-7. [PMID: 25213353 PMCID: PMC4235369 DOI: 10.1021/ja508523g] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Indexed: 01/09/2023]
Abstract
We report the development of a catalytic method for the enantioselective addition of indoles to pyrone-derived electrophiles. Arylpyrrolidino-derived thioureas catalyze the addition with high stereoselectivity in the presence of catalytic quantities of an achiral Brønsted acid. The indole-pyrone adducts feature a quaternary stereocenter and represent an unusual class of indolines bearing structural resemblance to the hybrid natural product pleiocarpamine.
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Affiliation(s)
- Charles
S. Yeung
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Robert E. Ziegler
- Department
of Chemistry and Center for Chemical Methodology and Library Development
(CMLD-BU), Boston University, Boston, Massachusetts 02215, United States
| | - John A. Porco
- Department
of Chemistry and Center for Chemical Methodology and Library Development
(CMLD-BU), Boston University, Boston, Massachusetts 02215, United States
| | - Eric N. Jacobsen
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
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6
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Witten MR, Jacobsen EN. Catalytic asymmetric synthesis of 8-oxabicyclooctanes by intermolecular [5+2] pyrylium cycloadditions. Angew Chem Int Ed Engl 2014; 53:5912-6. [PMID: 24782332 PMCID: PMC4109157 DOI: 10.1002/anie.201402834] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/26/2014] [Indexed: 01/30/2023]
Abstract
Highly enantioselective intermolecular [5+2] cycloadditions of pyrylium ion intermediates with electron-rich alkenes are promoted by a dual catalyst system composed of an achiral thiourea and a chiral primary aminothiourea. The observed enantioselectivity is highly dependent on the substitution pattern of the 5π component, and the basis for this effect is analyzed using experimental and computational evidence. The resultant 8-oxabicyclo[3.2.1]octane derivatives possess a scaffold common in natural products and medicinally active compounds and are also versatile chiral building blocks for further manipulations. Several stereoselective complexity-generating transformations of the 8-oxabicyclooctane products are presented.
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Affiliation(s)
- Michael R. Witten
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138 (USA), Fax: (+1) 617-496-1880
| | - Eric N. Jacobsen
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138 (USA), Fax: (+1) 617-496-1880
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7
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Witten MR, Jacobsen EN. Catalytic Asymmetric Synthesis of 8-Oxabicyclooctanes by Intermolecular [5+2] Pyrylium Cycloadditions. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402834] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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8
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Dange NS, Hong BC, Lee CC, Lee GH. One-Pot Asymmetric Synthesis of Seven-Membered Carbocycles Cyclohepta[b]indoles via a Sequential Organocatalytic Michael/Double Friedel–Crafts Alkylation Reaction. Org Lett 2013; 15:3914-7. [DOI: 10.1021/ol4016749] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nitin S. Dange
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan, R.O.C., and Instrumentation Center, National Taiwan University, Taipei, 106, Taiwan, R.O.C
| | - Bor-Cherng Hong
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan, R.O.C., and Instrumentation Center, National Taiwan University, Taipei, 106, Taiwan, R.O.C
| | - Chih-Ching Lee
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan, R.O.C., and Instrumentation Center, National Taiwan University, Taipei, 106, Taiwan, R.O.C
| | - Gene-Hsiang Lee
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan, R.O.C., and Instrumentation Center, National Taiwan University, Taipei, 106, Taiwan, R.O.C
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9
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Zou W, Vembaiyan K. Synthesis of 7-Oxabicyclo[2.2.1]heptanes and 8-Oxabicyclo[3.2.1]octanes from C-Glycosides via an Intramolecular Cyclization. J Org Chem 2013; 78:2703-9. [DOI: 10.1021/jo3024973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wei Zou
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6,
Canada
| | - Kannan Vembaiyan
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6,
Canada
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10
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Ylijoki KEO, Stryker JM. [5 + 2] Cycloaddition Reactions in Organic and Natural Product Synthesis. Chem Rev 2012; 113:2244-66. [PMID: 23153111 DOI: 10.1021/cr300087g] [Citation(s) in RCA: 310] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kai E. O. Ylijoki
- Department of Chemistry, University
of Alberta, Edmonton,
Alberta T6G 2G2, Canada
| | - Jeffrey M. Stryker
- Department of Chemistry, University
of Alberta, Edmonton,
Alberta T6G 2G2, Canada
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11
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Canham SM, Overman LE, Tanis PS. Identification of an Unexpected 2-Oxonia[3,3]sigmatropic Rearrangement/Aldol Pathway in the Formation of Oxacyclic Rings. Total Synthesis of (+)-Aspergillin PZ. Tetrahedron 2011; 67:9837-9843. [PMID: 22518066 PMCID: PMC3327308 DOI: 10.1016/j.tet.2011.09.079] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This paper reports the first unambiguous evidence that the cascade synthesis of tetrahydrofuran-containing oxacyclic molecules depicted in Scheme 12 can take place by a 2-oxonia[3,3]sigmatropic/aldol mechanism rather than by a Prins cyclization/pinacol rearrangement sequence. The 8-oxabicyclo[3.2.1]octyl aldehyde products of this reaction, 20 and 29, were employed to complete the first total synthesis of the structurally remarkable isoindolone alkaloid (+)-aspergillin PZ (1). The lack of activity seen in two tumor cell lines for synthetic (+)-aspergillin PZ calls into question the suggestion that aspergillin PZ, like many aspochalasin diterpenes, might exhibit useful antitumor properties.
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Affiliation(s)
- Stephen M Canham
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, CA 92697-2025
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12
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Burns NZ, Witten MR, Jacobsen EN. Dual catalysis in enantioselective oxidopyrylium-based [5 + 2] cycloadditions. J Am Chem Soc 2011; 133:14578-81. [PMID: 21848300 PMCID: PMC3173575 DOI: 10.1021/ja206997e] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method for effecting catalytic enantioselective intramolecular [5 + 2] cycloadditions based on oxidopyrylium intermediates is reported. The dual catalyst system consists of a chiral primary aminothiourea and a second achiral thiourea. Experimental evidence points to a new type of cooperative catalysis with each species being necessary to generate a reactive pyrylium ion pair that undergoes subsequent cycloaddition with high enantioselectivity.
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Affiliation(s)
- Noah Z. Burns
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Michael R. Witten
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Eric N. Jacobsen
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA 02138
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13
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Shimada N, Hanari T, Kurosaki Y, Takeda K, Anada M, Nambu H, Shiro M, Hashimoto S. Catalytic Asymmetric Synthesis of the endo-6-Aryl-8-oxabicyclo[3.2.1]oct-3-en-2-one Natural Product from Ligusticum chuanxing via 1,3-Dipolar Cycloaddition of a Formyl-Derived Carbonyl Ylide Using Rh2(S-TCPTTL)4. J Org Chem 2010; 75:6039-42. [DOI: 10.1021/jo101175b] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Naoyuki Shimada
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Taiki Hanari
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Yasunobu Kurosaki
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Koji Takeda
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Masahiro Anada
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Hisanori Nambu
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Motoo Shiro
- Rigaku Corporation, Akishima, Tokyo 196-8666, Japan
| | - Shunichi Hashimoto
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
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14
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Garnier EC, Liebeskind LS. Organometallic enantiomeric scaffolding: general access to 2-substituted oxa- and azabicyclo[3.2.1]octenes via a Brønsted acid catalyzed [5 + 2] cycloaddition reaction. J Am Chem Soc 2008; 130:7449-58. [PMID: 18479131 DOI: 10.1021/ja800664v] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
6-Substituted TpMo(CO) 2(eta-2,3,4-pyranyl)- and TpMo(CO) 2(eta-2,3,4-pyridinyl) scaffolds (Tp = hydridotrispyrazolylborato) function as reaction partners in an efficient regio- and stereocontrolled synthesis of functionalized oxa- and azabicyclo[3.2.1]octenes through a novel Brønsted acid catalyzed [5 + 2] cycloaddition reaction. Excellent exo-selectivities are obtained, and the reaction gives products with complete retention of enantiomeric purity when carried out with chiral, nonracemic scaffolds. The substituent at C-6 of the eta (3)-coordinated heterocyclic scaffold not only influences [5 + 2] reactivity but also plays a critical role in the demetalation step directing the reaction to only one of two possible products.
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Affiliation(s)
- Ethel C Garnier
- Emory University, Department of Chemistry, 1515 Dickey Drive, Atlanta, Georgia 30322, USA
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15
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Singh V, Murali Krishna U, Vikrant, Trivedi GK. Cycloaddition of oxidopyrylium species in organic synthesis. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.01.049] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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17
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Zou W, Shao H, Wu SH. Intramolecular aldol cyclization of C-4-ulopyranosyl-2'-oxoalkanes controlled by steric effects. Asymmetric synthesis of substituted 8-oxabicyclo[3.2.1]octanones and -octenones and cyclopentenones. Carbohydr Res 2004; 339:2475-85. [PMID: 15476708 DOI: 10.1016/j.carres.2004.08.008] [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] [Received: 05/26/2004] [Accepted: 08/13/2004] [Indexed: 11/23/2022]
Abstract
Whereas C-2- and 4-ulopyranosyl compounds (C-2- and C-4-ulosides) can be converted to cyclopentenones under base conditions through beta-elimination and ring contraction, base-initiated beta-elimination of C-glycosyl 2'-aldehydes and 2'-ketones results in the formation of acyclic alpha,beta-unsaturated aldehydes or ketones. By combining both molecular features we synthesized 1-C-(4-ulopyranosyl)-2-oxoalkanes 6, 13, and 20 and investigated their reactions when they were treated with base. Both alpha- and beta-anomers of C-(4-ulopyranosyl)acetaldehydes 6 and 13 underwent a fast intramolecular aldol reaction between the C-5 enolate and 2'-aldehyde to form optically pure 8-oxabicyclo[3.2.1]octanones, which further transformed to 8-oxabicyclo[3.2.1]octenones 14 and 15 by beta-elimination. However, this aldol reaction did not occur when 1-C-(4-ulopyranosyl)propan-2-one 20 was treated with base because of steric hindrance exerted by the additional methyl group. Instead, an alternate C-3 enolization led to beta-elimination and further electro-ring opening to form an acyclic enol, which was then converted through a disrotatory intramolecular aldol cyclization to a cis-substituted cyclopentenone 21.
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Affiliation(s)
- Wei Zou
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.
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18
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Asymmetric oxidopyrylium-alkene [5+2] cycloaddition: a divergent approach for the synthesis of enantiopure oxabicyclo[5.4.0]undecanes. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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López F, Castedo L, Mascareñas JL. A Theoretical Rationalization of the Asymmetric Induction in Sulfinyl-Directed [5C + 2C] Intramolecular Cycloadditions. J Org Chem 2003; 68:9780-6. [PMID: 14656107 DOI: 10.1021/jo035259p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A computational DFT examination (B3LYP/6-31G and B3LYP/6-311+G//B3LYP/6-31G) of the thermal [5C + 2C] cycloaddditions of 6-acetoxy-3-pyranones and 3-silyloxy-4-pyrones with tethered alkenyl sulfoxides confirms that the high level of diastereofacial selectivity obtained is ultimately due to the preference of the alkenesulfinyl group to adopt a well-defined conformation in the transition state of the reaction. This conformation, which is different from that found in the ground state, is most probably dictated by dipolar interaction effects between the sulfoxide and the oxidopyrylium ylide intermediate.
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Affiliation(s)
- Fernando López
- Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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20
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López F, Castedo L, Mascareñas JL. A sulfinyl-directed asymmetric [5C + 2C] intramolecular acetoxypyranone-alkene cycloaddition. Org Lett 2002; 4:3683-5. [PMID: 12375918 DOI: 10.1021/ol026633v] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Introduction of a homochiral p-tolylsulfinyl group at the trans terminal position of an alkene induces a total diastereodifferentiation in the intramolecular cycloaddition of the latter to 3-oxidopyrylium ylide precursors. The cycloadducts can be readily desulfinylated to afford enantiomerically pure oxa-bridged bicyclo[5.3.0]decane ring systems. Theoretical calculations confirm that diastereoselectivity stems from the conformational preferences of the alkenylsulfoxide unit in the transition state of the reaction.
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Affiliation(s)
- Fernando López
- Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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21
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López F, Castedo L, Mascareñas JL. A practical route to enantiopure, highly functionalized seven-membered carbocycles and tetrahydrofurans: concise synthesis of (+)-nemorensic Acid. Chemistry 2002; 8:884-99. [PMID: 11857703 DOI: 10.1002/1521-3765(20020215)8:4<884::aid-chem884>3.0.co;2-q] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Highly diastereoselective thermal [5C+2C] intramolecular pyrone-alkene cycloadditions can be achieved by introducing a homochiral p-tolylsulfinyl group at a suitable position of the alkene. The resulting adducts can be readily desulfinylated to give optically active 8-oxabicyclo[3.2.1]octane derivatives. Interestingly, switching from a sulfinyl to a sulfonimidoyl group allows one to reverse the direction of the diastereofacial selectivity and thereby produces oxa-bridged carbocyclic systems enantiomeric to those obtained from the sulfinyl precursors. Cleavage of the oxa-bridge on the desulfurated adducts yields highly functionalized seven-membered carbocyclic derivatives in enantiopure form. Alternative cleavage of the seven-membered carbocycle provides enantiomerically enriched tetrahydrofurans. We have exploited this reaction pathway for the synthesis of the naturally occurring enantiomer of nemorensic acid.
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Affiliation(s)
- Fernando López
- Departamento de Química Orgánica y Unidad Asociada al CSIC Universidad de Santiago de Compostela 15782 Santiago de Compostela, Spain
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22
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López F, Castedo L, Mascareñas JL. Reversal of stereoselectivity in [5 + 2] pyrone--alkene cycloadditons using a sulfoxide-to-sulfoximine switch. Enantiodivergent synthesis of 8-oxabicyclo[3.2.1]octane systems. Org Lett 2001; 3:623-5. [PMID: 11178841 DOI: 10.1021/ol007061m] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Switching from a sulfinyl to a sulfonimidoyl group allows the reversal of the sense of asymmetric induction in thermal [5C + 2C] intramolecular pyrone-alkene cycloadditions. Removal of the sulfoximine unit from the resulting cycloadducts yields optically active oxabicyclic systems that are enantiomeric to those obtained using the sulfinyl chiral auxiliary.
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Affiliation(s)
- F López
- Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
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