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Fulton BB, Hartzell AJ, Dias HVR, Lovely CJ. Room Temperature Diels-Alder Reactions of 4-Vinylimidazoles. Molecules 2024; 29:1902. [PMID: 38675720 PMCID: PMC11053432 DOI: 10.3390/molecules29081902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/30/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
In the course of studying Diels-Alder reactions of 4-vinylimidazoles with N-phenylmaleimide, it was discovered that they engage in cycloaddition at room temperature to give high yields of the initial cycloadduct as a single stereoisomer. In certain cases, the product precipitated out of the reaction mixture and could be isolated by simple filtration, thereby avoiding issues with aromatization observed during chromatographic purification. Given these results, intramolecular variants using doubly activated dienophiles were also investigated at room temperature. Amides underwent cycloaddition at room temperature in modest yields, but the initial adducts were not isolable with Nimid-benzyl-protected systems. Attempts to extend these results to the corresponding esters and hydroxamate were less successful with these substrates only undergoing cycloaddition at elevated temperatures in lower yields. Density functional theory calculations were performed to evaluate the putative transition states for both the inter- and intramolecular variants to rationalize experimental observations.
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Affiliation(s)
| | | | | | - Carl J. Lovely
- Department of Chemistry and Biochemistry, University of Texas Arlington, Arlington, TX 76019, USA
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Zubkov FI, Krishna G, Grudinin DG, Nikitina EV. IntraMolecular Diels–Alder Reactions of Vinylarenes and Alkynyl Arenes (the IMDAV Reaction). SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/s-0040-1705983] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractThis comprehensive review summarizes the published literature data concerning the intramolecular Diels–Alder reactions of vinylarenes (the IMDAV reaction) and alkynyl arenes from 1970 to 2019, and covers mainly intramolecular [4+2] cycloaddition reactions of vinyl- or acetylene-substituted furans, thiophenes, pyrroles, indoles, imidazoles, benzenes, and naphthalenes, in which the unsaturated substituent is linked directly to an arene moiety. The selected area of the Diels–Alder reaction differs from other forms of [4+2] cycloadditions due to the uniqueness of the diene fragment, which, along with an exocyclic multiple bond, includes the double bond of an aromatic or heteroaromatic nucleus in its system. Thus, during the formation of the [4+2] cycloaddition intermediate, the aromaticity of furan, thiophene and even benzene rings is broken, leading, as a rule, to the formation of heterocyclic structures rarely accessible by other methods, in contrast to the majority of intermolecular Diels–Alder reactions, with the highest degree of chemo-, regio-, and diastereoselectivity. Therefore, the IMDAV approach is often used for the synthesis of naturally occurring and bioactive molecules, which are also discussed in this review alongside other applications of this reaction. Whenever possible, we have tried to avoid examples of radical, photochemical, oxidative, precious-metal-complex-catalyzed cyclizations and other types of formal [4+2] cycloadditions, focusing on thermal Diels–Alder reactions in the first step, according to the classical mechanism. The second stage of the process, aromatization, is unique for many initial substrates, and hence considerable attention in this overview is given to the detailed description of the reaction mechanisms.1 Introduction2 IMDAV Reactions of Vinylfurans2.1 Alkenes as Internal Dienophiles2.2 Alkynes and Allenes as Internal Dienophiles3 IMDAV Reactions of Vinylthiophenes3.1 Alkenes as Internal Dienophiles3.2 Alkynes as Internal Dienophiles4 IMDAV Reactions of Vinylbenzothiophenes5 IMDAV Reactions of Vinylpyrroles6 IMDAV Reactions of Vinylindoles6.1 Alkenes as Internal Dienophiles6.2 Alkynes as Internal Dienophiles7 IMDAV Reactions of Styrenes and Vinylnaphthalenes7.1 Alkenes as Internal Dienophiles7.2 Alkynes as Internal Dienophiles7.3 Alkynes as Internal Dienophiles in Aryl Acetylenes (the Intramolecular Dehydro Diels–Alder Reaction)8 IMDAV Reactions of Vinylimidazoles, Vinylisoxazoles and Vinylpyridines9 Conclusion10 Abbreviations
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Nájera C, Sansano JM, Yus M. Diels-Alder reactions of 1-amino-1,3-dienes and related systems. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Murakata M, Kawase A, Kimura N, Ikeda T, Nagase M, Koizumi M, Kuwata K, Maeda K, Shimizu H. Synthesis of Tofogliflozin as an SGLT2 Inhibitor via Construction of Dihydroisobenzofuran by Intramolecular [4 + 2] Cycloaddition. Org Process Res Dev 2019. [DOI: 10.1021/acs.oprd.8b00400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Masatoshi Murakata
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Akira Kawase
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Nobuaki Kimura
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Takuma Ikeda
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Masahiro Nagase
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Masatoshi Koizumi
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Kazuaki Kuwata
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Kenji Maeda
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
| | - Hitoshi Shimizu
- API Process Development Department, Chugai Pharmaceutical Co., Ltd., 5-5-1 Ukima, Kita-Ku, Tokyo 115-8543, Japan
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J. Lovely C, Ray A, Mukherjee S, Das J, Bhandari M, Herath A, Yousufuddin M. Heterosubstituted 4-Vinylimidazoles – Preparation and Diels-Alder Reactions. HETEROCYCLES 2019. [DOI: 10.3987/com-18-s(f)27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Ray A, Yousufuddin M, Gout D, Lovely CJ. Intramolecular Diels-Alder Reaction of a Silyl-Substituted Vinylimidazole en Route to the Fully Substituted Cyclopentane Core of Oroidin Dimers. Org Lett 2018; 20:5964-5968. [PMID: 30192150 DOI: 10.1021/acs.orglett.8b02675] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An intramolecular Diels-Alder reaction of a silyl-substituted vinylimidazole delivers a diastereomeric mixture of C4-silyl functionalized dihydrobenzimidazoles. Subsequent diastereoselective reduction and elaboration of the lactone gives rise to a polysubstituted tetrahydrobenzimidazole, which, upon oxidative rearrangement, affords a single spirofused imidazolone containing all of the relevant functionality for an approach to the oroidin dimers axinellamine, massadine, and palau'amine.
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Affiliation(s)
- Abhisek Ray
- Department of Chemistry and Biochemistry , University of Texas-Arlington , Arlington , Texas 76019-0065 , United States
| | - Muhammed Yousufuddin
- Department of Chemistry and Biochemistry , University of Texas-Arlington , Arlington , Texas 76019-0065 , United States
| | - Delphine Gout
- Department of Chemistry and Biochemistry , University of Texas-Arlington , Arlington , Texas 76019-0065 , United States
| | - Carl J Lovely
- Department of Chemistry and Biochemistry , University of Texas-Arlington , Arlington , Texas 76019-0065 , United States
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Zaytsev VP, Sorokina EA, Kvyatkovskaya EA, Toze FAA, Mhaldar SN, Dorovatovskii PV, Khrustalev VN. Three-component reaction between isatoic anhydride, amine and meth-yl-subs-tituted furyl-acryl-alde-hydes: crystal structures of 3-benzyl-2-[( E)-2-(5-methylfuran-2-yl)vin-yl]-2,3-di-hydro-quinazolin-4(1 H)-one, 3-benzyl-2-[( E)-2-(furan-2-yl)-1-methyl-vin-yl]-2,3-di-hydro-quinazolin-4(1 H)-one and 3-(furan-2-ylmeth-yl)-2-[( E)-2-(furan-2-yl)-1-methyl-vin-yl]-2,3-di-hydro-quinazolin-4(1 H)-one. Acta Crystallogr E Crystallogr Commun 2018; 74:1101-1106. [PMID: 30116571 PMCID: PMC6072988 DOI: 10.1107/s2056989018009982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/11/2018] [Indexed: 11/11/2022]
Abstract
Compounds (I), C22H20N2O2, (II), C22H20N2O2 and (III), C20H18N2O3 are the products of three-component reactions between isatoic anhydride, the corresponding amine and 3-(5-methylfuran-2-yl)- or (furan-2-yl)-2-methyl-acryl-aldehyde. Compound (I) crystallizes in the monoclinic space group P21/n, while compounds (II) and (III) are isostructural and crystallize in the ortho-rhom-bic space group Pbca. The tetra-hydro-pyrimidine ring in (I)-(III) adopts a sofa conformation. The NH nitro-gen atom has a trigonal-pyramidal geometry, whereas the N(R) nitro-gen atom is flattened. The furyl-vinyl substituents in (I)-(III) are practically planar and have an E configuration at the C=C double bond. In (I), this bulky fragment occupies the axial position at the quaternary carbon atom of the tetra-hydro-pyrimidine ring, whereas in (II) and (III) it is equatorially disposed. In the crystal of (I), mol-ecules form hydrogen-bonded chains propagating along [001] by strong inter-molecular N-H⋯O hydrogen bonds. The chains are packed in stacks along the a-axis direction. In the crystals of (II) and (III), mol-ecules also form hydrogen-bonded chains propagating along [100] by strong inter-molecular N-H⋯O hydrogen bonds. However, despite the fact that compounds (II) and (III) are isostructural, steric differences between the phenyl and furyl substituents result in chains with different geometries. Thus in the crystal of (II) the chains have a zigzag-like structure, whereas in the crystal of (III), they are almost linear. In both (II) and (III), the hydrogen-bonded chains are further packed in stacks along the b-axis direction.
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Affiliation(s)
- Vladimir P. Zaytsev
- Organic Chemistry Department, Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation
| | - Elena A. Sorokina
- Organic Chemistry Department, Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation
| | - Elisaveta A. Kvyatkovskaya
- Organic Chemistry Department, Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation
| | - Flavien A. A. Toze
- Department of Chemistry, Faculty of Sciences, University of Douala, PO Box 24157, Douala, Republic of , Cameroon
| | - Shashank N. Mhaldar
- Department of Chemistry, Goa University, Taleigao Plateau, Goa 403 206, India
| | - Pavel V. Dorovatovskii
- National Research Centre "Kurchatov Institute", 1 Acad. Kurchatov Sq., Moscow 123182, Russian Federation
| | - Victor N. Khrustalev
- National Research Centre "Kurchatov Institute", 1 Acad. Kurchatov Sq., Moscow 123182, Russian Federation
- Inorganic Chemistry Department, Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation
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Ma Z, Chen C. Natural products as inspiration for the development of new synthetic methods. J CHIN CHEM SOC-TAIP 2018; 65:43-59. [PMID: 29430058 PMCID: PMC5800783 DOI: 10.1002/jccs.201700134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Natural products have played an important role in shaping modern synthetic organic chemistry. In particular, their complex molecular skeletons have stimulated the development of many new synthetic methods. We highlight in this article some recent examples of synthetic design inspired by the biosynthesis of natural products.
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Affiliation(s)
- Zhiqiang Ma
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, USA
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, P. R. China
| | - Chuo Chen
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, USA
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Horak YI, Lytvyn RZ, Laba YOV, Homza YV, Zaytsev VP, Nadirova MA, Nikanorova TV, Zubkov FI, Varlamov AV, Obushak MD. The intramolecular Diels-Alder vinylthiophen (IMDAV) reaction: An easy approach to thieno[2,3-f]isoindole-4-carboxylic acids. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.09.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Lindel T. Chemistry and Biology of the Pyrrole–Imidazole Alkaloids. THE ALKALOIDS: CHEMISTRY AND BIOLOGY 2017; 77:117-219. [DOI: 10.1016/bs.alkal.2016.12.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Enantioselective synthesis of functionalised tetrahydrocarbazoles via an organocatalysed Diels–Alder/ene reaction strategy. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.tetasy.2015.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ray A, Mukherjee S, Das J, Bhandari MK, Du H, Yousufuddin M, Lovely CJ. Preparation and Diels-Alder reactions of 1'-heterosubsituted vinylimidazoles. Tetrahedron Lett 2015; 56:3518-3522. [PMID: 26139945 PMCID: PMC4484863 DOI: 10.1016/j.tetlet.2015.01.190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A Diels-Alder/rearrangement sequence has been pursued in our lab en route to a number of oroidin dimers. In order to access the fully substituted core of these molecules, 1',2'-disubstituted 4-vinylimidazoles were required as dienes. The preparation of a series of a 4-vinylimidazoles containing substituents on the vinyl moiety via hydroalumination/electrophilic trapping or hydrosilylation are described. These derivatives undergo Diels-Alder reactions with N-phenylmaleimide to provide the tetrahydrobenzimidazole derivatives. The cycloadducts derived from halosubstituted systems generally undergo elimination, leading to the corresponding dihydrobenzimidazole, whereas the silyl and stannyl derivatives provide the corresponding 4-substituted tetrahydrobenzimidazole.
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Affiliation(s)
- Abhisek Ray
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Sabuj Mukherjee
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Jayanta Das
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Manoj K. Bhandari
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Hongwang Du
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Muhammed Yousufuddin
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
| | - Carl J. Lovely
- Department of Chemistry and Biochemistry, The University of Texas at Arlington,
Arlington, Texas 76019-0065, USA
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Kim KH, Lim JW, Moon HR, Kim JN. Synthesis of Arene-Fused Isoindoline Derivatives from Morita-Baylis-Hillman Adducts by IMDA Reaction Using Z-Vinylarenes as 1,3-Dienes. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.11.3254] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Lima H, Sivappa R, Yousufuddin M, Lovely CJ. Total synthesis of 7'-desmethylkealiiquinone, 4'-desmethoxykealiiquinone, and 2-deoxykealiiquinone. J Org Chem 2014; 79:2481-90. [PMID: 24533685 PMCID: PMC3986028 DOI: 10.1021/jo4027337] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Indexed: 12/24/2022]
Abstract
Synthetic approaches to the imidazonaphthoquinone core of kealiiquinone and related Leucetta-derived alkaloids are described. The polysubstituted benzimidazole framework can be constructed through intramolecular Diels-Alder reactions of propiolate-derived enynes followed by oxidation. Adjustment of the oxidation state of the thus formed lactone allows introduction of the 2,3-dihydroxybenzoquinone moiety through a presumed benzoin-like condensation between a phthaldehyde derivative and a masked glyoxal equivalent catalyzed by a cyanide ion. Oxidation of the C2-position can be accomplished through application of an operationally simple treatment of an imidazolium salt with bleach, thus producing the corresponding 2-imidazolone. Debenzylation of a late stage intermediate en route to kealiiquinone was compromised by concomitant O-demethylation upon treatment with triflic acid resulting in the formation of non-natural 7'-desmethylkealiiquinone. Other endgame strategies were evaluated; however, these efforts did not lead to completion of a synthesis of kealiiquinone but did provide access to other closely related analogues.
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Affiliation(s)
- Heather
M. Lima
- Department
of Chemistry and
Biochemistry, University of Texas at Arlington, Arlington, Texas 76019-0065, United States
| | | | - Muhammed Yousufuddin
- Department
of Chemistry and
Biochemistry, University of Texas at Arlington, Arlington, Texas 76019-0065, United States
| | - Carl J. Lovely
- Department
of Chemistry and
Biochemistry, University of Texas at Arlington, Arlington, Texas 76019-0065, United States
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Ding H, Roberts AG, Harran PG. Total Synthesis of Ageliferin via Acyl N-amidinyliminium Ion Rearrangement. Chem Sci 2013; 4:303-306. [PMID: 23687567 PMCID: PMC3653441 DOI: 10.1039/c2sc21651e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ageliferin is a marine natural product having antiviral and antimicrobial activities. These functions remain to be characterized at a molecular level. Ageliferin is also thought a biosynthetic intermediary linking oroidin type alkaloids to more complex polycyclic derivatives. This scenario has the amino tetrahydrobenzimidazole motif in ageliferin serving as a reduced progenitor of oxidized, ring-contracted spirocycles. Here we describe the reverse. Namely, a concise synthesis of ageliferin which features ring expansion of a spirocyclic precursor - itself derived from reduction. The pathway also provides access to unique isosteres of the axinellamine ring system, allowing new synthetic additions to the growing family of pyrrole / imidazole alkaloids.
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Affiliation(s)
- Hui Ding
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, East, Los Angeles, CA 90095-1569, USA
| | - Andrew G. Roberts
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, East, Los Angeles, CA 90095-1569, USA
| | - Patrick G. Harran
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, East, Los Angeles, CA 90095-1569, USA
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Lima HM, Sivappa R, Yousufuddin M, Lovely CJ. Total synthesis of 7'-desmethylkealiiquinone. Org Lett 2012; 14:2274-7. [PMID: 22530654 DOI: 10.1021/ol300704w] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The total synthesis of an analogue of the marine alkaloid kealiiquinone has been completed through application of an intramolecular Diels-Alder reaction of an imidazole-containing enyne. Oxidative aromatization of the lactone adduct and N-methylation facilitates C2-oxidation via the imidazolium salt. Conversion of the lactone to the phthalaldehyde derivative and then to the dihydroxybenzoquinone was achieved via a reaction with glyoxal in the presence of KCN. Esterification of the vinylogous diacid and deprotection provided 7'-desmethylkealiiquinone.
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Affiliation(s)
- Heather M Lima
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019, United States
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Development of a General Approach to the Leucetta-Derived Alkaloids. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/b978-0-12-386540-3.00008-3] [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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Watson LJ, Harrington RW, Clegg W, Hall MJ. Diastereoselective intermolecular ene reactions: synthesis of 4,5,6,7-tetrahydro-1H-benzo[d]imidazoles. Org Biomol Chem 2012; 10:6649-55. [DOI: 10.1039/c2ob26009c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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