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Biswas S, De Angelis L, Rivera G, Arman H, Doyle MP. Inverse Electron Demand Diels-Alder-Type Heterocycle Syntheses with 1,2,3-Triazine 1-Oxides: Expanded Versatility. Org Lett 2023; 25:1104-1108. [PMID: 36787541 DOI: 10.1021/acs.orglett.2c04360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
1,2,3-Triazine 1-oxides are remarkably effective substrates for inverse electron demand Diels-Alder reactions. Formed from vinyldiazoacetates via reaction with tert-butyl nitrite, these stable heterocyclic compounds undergo clean nucleophilic addition with amidines to form pyrimidines, with β-ketocarbonyl compounds and related nitrile derivatives to form polysubstituted pyridines and with 3/5-aminopyrazoles to form pyrazolo[1,5-a]pyrimidines, in high yield. These practical reactions are rapid at room temperature, are base catalyzed, and offer a diversity of structural modifications.
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Affiliation(s)
- Soumen Biswas
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Luca De Angelis
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Gildardo Rivera
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710 Reynosa, México
| | - Hadi Arman
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Michael P Doyle
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
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Zhang FG, Chen Z, Tang X, Ma JA. Triazines: Syntheses and Inverse Electron-demand Diels-Alder Reactions. Chem Rev 2021; 121:14555-14593. [PMID: 34586777 DOI: 10.1021/acs.chemrev.1c00611] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Triazines are an important class of six-membered aromatic heterocycles possessing three nitrogen atoms, resulting in three types of regio-isomers: 1,2,4-triazines (a-triazines), 1,2,3-triazines (v-triazines), and 1,3,5-triazines (s-triazines). Notably, the application of triazines as cyclic aza-dienes in inverse electron-demand Diels-Alder (IEDDA) cycloaddition reactions has been established as a unique and powerful method in N-heterocycle synthesis, natural product preparation, and bioorthogonal chemistry. In this review, we comprehensively summarize the advances in the construction of these triazines via annulation and ring-expansion reactions, especially emphasizing recent developments and challenges. The synthetic transformations of triazines are focused on IEDDA cycloaddition reactions, which have allowed access to a wide scope of heterocycles, including pyridines, carbolines, azepines, pyridazines, pyrazines, and pyrimidines. The utilization of triazine IEDDA reactions as key steps in natural product synthesis is also discussed. More importantly, a particular attention is paid on the bioorthogonal application of triazines in fast click ligation with various strained alkenes and alkynes, which opens a new opportunity for studying biomolecules in chemical biology.
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Affiliation(s)
- Fa-Guang Zhang
- Department of Chemistry, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), and Tianjin Collaborative Innovation Center of Chemical Science & Engineering, Tianjin University, Tianjin 300072, P. R. China.,Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P. R. China
| | - Zhen Chen
- College of Chemical Engineering, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing Forestry University, Nanjing, Jiangsu 210037, P. R. China
| | - Xiaodong Tang
- Department of Chemistry, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), and Tianjin Collaborative Innovation Center of Chemical Science & Engineering, Tianjin University, Tianjin 300072, P. R. China.,Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P. R. China
| | - Jun-An Ma
- Department of Chemistry, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), and Tianjin Collaborative Innovation Center of Chemical Science & Engineering, Tianjin University, Tianjin 300072, P. R. China.,Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P. R. China
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3
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Xu G, Bai X, Dang Q. Aromatic Heterocycles as Productive Dienophiles in the Inverse Electron-Demand Diels-Alder Reactions of 1,3,5-Triazines. Acc Chem Res 2020; 53:773-781. [PMID: 32227911 DOI: 10.1021/acs.accounts.9b00604] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Heterocycles are often found as the structural nucleus in natural products and biological active compounds. Consequently, research toward the discovery and development of novel and efficient synthetic methodologies is of constant interest to organic chemists. Diels-Alder reactions are powerful at forming multiple bonds simultaneously, often with stereoselectivity, and thus are one of the most widely used synthetic methodologies in organic syntheses. Inverse electron-demand Diels-Alder (IEDDA) reactions, a subclass of Diels-Alder reactions, have been developed for the efficient synthesis of various heterocycles, with 1,3,5-triazines used as azadienes. The initial 1,3,5-triazine IEDDA reactions mostly included nonaromatic, electron-rich species such as vinyl ethers, enamines, ynamines, and amidines as dienophiles, producing in high yields pyrimidine derivatives with excellent regioselectivity. We hypothesized that some electron-rich aromatic heterocycles could be studied as potential dienophiles for 1,3,5-triazine IEDDA reactions; 5-aminopyrazoles proved to be productive dienophiles leading to high yields of pyrazolopyrimidines. Subsequently, many studies were reported to investigate the mechanism and scope of this new type of IEDDA reaction. Mechanistically, this new type of IEDDA reaction is quite interesting since it entails two aromatic compounds proceeding through a perceived high energy nonaromatic transition state, leading to a new aromatic compound, a counterintuitive process. Both theoretical and experimental studies provide key insights to this reaction mechanism, with learnings from these studies possibly stimulating unconventional thinking in other areas. Theoretical calculations of these cascade reactions of amino-substituted heterocycles with 1,3,5-triazines indicate that the reactions occur in a stepwise fashion via a highly polar zwitterionic intermediate; elimination of ammonia from IEDDA adducts and subsequent retro Diels-Alder reaction drive the reaction toward the fully aromatized IEDDA products. This amino substituent is critical in determining the regioselectivity and driving the cascade reactions to completion. With regard to reaction scope, many amino-heterocycles such as pyrroles, imidazoles, furans, thiophenes, and indoles all proved to be productive dienophiles for this new IEDDA reaction, leading to various fused-pyrimidines in a single step with moderate to high yields and high regioselectivity. Application of this new IEDDA reaction with 1,3,5-triazines was reported to lead to interesting heterocyclic compounds such as nucleoside natural product nebularine and analogues, as well as fluorine-containing fused pyrimidines with potential for biological activities.Herein, the scope of various aromatic heterocycles as dienophiles in the 1,3,5-triazine IEDDA reaction is reviewed. Moreover, both experimental and theoretical studies of the mechanisms for this interesting cascade IEDDA reaction are discussed. Finally, applications of this new type (aromatic heterocycles as dienophiles with 1,3,5-triazines as azadienes) of IEDDA reaction are also covered.
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Affiliation(s)
- Guoxing Xu
- The Center for Combinatorial Chemistry and Drug Discovery of Jilin University, The School of Pharmaceutical Sciences, Jilin University, 1266 Fujin Road, Changchun, Jilin 130021, P.R. China
| | - Xu Bai
- The Center for Combinatorial Chemistry and Drug Discovery of Jilin University, The School of Pharmaceutical Sciences, Jilin University, 1266 Fujin Road, Changchun, Jilin 130021, P.R. China
| | - Qun Dang
- The Center for Combinatorial Chemistry and Drug Discovery of Jilin University, The School of Pharmaceutical Sciences, Jilin University, 1266 Fujin Road, Changchun, Jilin 130021, P.R. China
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Yang K, Yang Z, Dang Q, Bai X. Hydrazones as Productive Dienophiles in the Inverse Electron Demand Diels-Alder Reactions of 1,3,5-Triazines. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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De Rosa M, Arnold D, Hartline D. Four Mechanisms in the Reactions of 3-Aminopyrrole with 1,3,5-Triazines: Inverse Electron Demand Diels–Alder Cycloadditions vs SNAr Reactions via Uncatalyzed and Acid-Catalyzed Pathways. J Org Chem 2013; 78:8614-23. [DOI: 10.1021/jo4012915] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael De Rosa
- Department of Chemistry, Penn State Brandywine, 25 Yearsley Mill Road, Media, Pennsylvania 19063, United States
| | - David Arnold
- Department of Chemistry, Penn State Brandywine, 25 Yearsley Mill Road, Media, Pennsylvania 19063, United States
| | - Douglas Hartline
- Department of Chemistry, Penn State Brandywine, 25 Yearsley Mill Road, Media, Pennsylvania 19063, United States
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Iaroshenko VO, Maalik A, Ostrovskyi D, Villinger A, Spannenberg A, Langer P. Efficient synthesis of purines by inverse electron-demand Diels–Alder reactions of 1-substituted-1H-imidazol-5-amines with 1,3,5-triazines. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.08.082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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7
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Xu G, Zheng L, Wang S, Dang Q, Bai X. Synthesis of Electron-Deficient 1,3,5-Triazines as Potential Azadienes for Inverse-Electron-Demand Diels–Alder Reactions. SYNTHETIC COMMUN 2010. [DOI: 10.1080/00397910902978031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Guoxing Xu
- a The Center for Combinatorial Chemistry and Drug Discovery, College of Chemistry and School of Pharmaceutical Sciences, Jilin University , Changchun, China
| | - Lianyou Zheng
- a The Center for Combinatorial Chemistry and Drug Discovery, College of Chemistry and School of Pharmaceutical Sciences, Jilin University , Changchun, China
| | - Shixue Wang
- a The Center for Combinatorial Chemistry and Drug Discovery, College of Chemistry and School of Pharmaceutical Sciences, Jilin University , Changchun, China
| | - Qun Dang
- a The Center for Combinatorial Chemistry and Drug Discovery, College of Chemistry and School of Pharmaceutical Sciences, Jilin University , Changchun, China
| | - Xu Bai
- a The Center for Combinatorial Chemistry and Drug Discovery, College of Chemistry and School of Pharmaceutical Sciences, Jilin University , Changchun, China
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Aksenov AV, Aksenova IV. Use of the ring opening reactions of 1,3,5-triazines in organic synthesis (review). Chem Heterocycl Compd (N Y) 2009. [DOI: 10.1007/s10593-009-0243-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Dang Q, Carruli E, Tian F, Dang FW, Gibson T, Li W, Bai H, Chung M, Hecker SJ. A tandem decarboxylation and inverse electron-demand Diels–Alder reaction of amino-thiophenecarboxylic acids with 1,3,5-triazines. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.03.180] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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De Rosa M, Arnold D. Electronic and Steric Effects on the Mechanism of the Inverse Electron Demand Diels−Alder Reaction of 2-Aminopyrroles with 1,3,5-Triazines: Identification of Five Intermediates by 1H, 13C, 15N, and 19F NMR Spectroscopy. J Org Chem 2008; 74:319-28. [DOI: 10.1021/jo8019626] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael De Rosa
- Department of Chemistry, Penn State Brandywine, 25 Yearsley Mill Road, Media, Pennsylvania 19063
| | - David Arnold
- Department of Chemistry, Penn State Brandywine, 25 Yearsley Mill Road, Media, Pennsylvania 19063
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11
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Yu ZX, Dang Q, Wu YD. Clarification of the Mechanism of the Cascade Reactions between Amino-Substituted Heterocycles and 1,3,5-Triazines. J Org Chem 2005; 70:998-1005. [PMID: 15675860 DOI: 10.1021/jo049248n] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanisms of the cascade reactions of amino-substituted imidazoles, pyrroles, and pyrazoles with 1,3,5-triazines have been studied using first principle MP2/6-311++G**//B3LYP/6-31G* calculations in both the gas phase and solution. Calculations indicate that these cascade reactions start with stepwise inverse-electron demand Diels-Alder (IDA) reactions, followed by elimination of ammonia from the IDA adducts, and retro Diels-Alder (RDA) reactions (referred as to the IER path). An alternative IRE path involving a reaction sequence of IDA, RDA, and elimination of ammonia is ruled out since the RDA transition states in this pathway are higher in energy than the reactants by as much as 50 kcal/mol. The preference of the IER over the IRE path is discussed.
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Affiliation(s)
- Zhi-Xiang Yu
- Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Padwa A, Brodney MA, Lynch SM, Rashatasakhon P, Wang Q, Zhang H. A New Strategy toward Indole Alkaloids Involving an Intramolecular Cycloaddition/Rearrangement Cascade. J Org Chem 2004; 69:3735-45. [PMID: 15153003 DOI: 10.1021/jo049808i] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The intramolecular Diels-Alder reaction between an amidofuran moiety tethered onto an indole component was examined as a strategy for the synthesis of Aspidosperma alkaloids. Furanyl carbamate 23 was acylated using the mixed anhydride 26 to provide amidofuran 22 in 68% yield. Further N-acylation of this indole furnished 27 in 88% yield. Cyclization precursors were prepared by removing the carbamate moiety followed by N-alkylation with the appropriate alkyl halides. Large substituent groups on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be more highly populated, thereby facilitating the Diels-Alder cycloaddition. The reaction requires the presence of an electron-withdrawing substituent on the indole nitrogen in order for the cycloaddition to proceed. Treatment of N-allyl-bromoenamide 48 with n-Bu(3)SnH/AIBN preferentially led to the 6-endo trig cyclization product 50, with the best yield (91%) being obtained under high dilution conditions. The initially generated cyclohexenyl radical derived from 48 produces the pentacyclic heterocycle 50 by either a direct 6-endo trig cyclization or, alternatively, by a vinyl radical rearrangement pathway.
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Affiliation(s)
- Albert Padwa
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
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Dang Q, Gomez-Galeno JE. An efficient synthesis of pyrrolo[2,3-d]pyrimidines via inverse electron demand diels-alder reactions of 2-amino-4-cyanopyrroles with 1,3,5-triazines. J Org Chem 2002; 67:8703-5. [PMID: 12444666 DOI: 10.1021/jo026309d] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The scope of the inverse electron demand Diels-Alder reaction of 2-amino-4-cyanopyrroles (3a-e) with 1,3,5-triazines (1, 2) is reported. This methodology is suitable for one-pot syntheses of highly substituted and highly functionalized pyrrolo[2,3-d]pyrimidines that are the central heterocyclic nucleus of various nucleoside natural products such as toyocamycin, sangivamycin, and tubercidin.
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Affiliation(s)
- Qun Dang
- Department of Medicinal Chemistry, Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, Suite 300, San Diego, California 92121, USA.
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Bodwell GJ, Li J. Concise synthesis and transannular inverse electron demand Diels-Alder reaction of [3](3,6)pyridazino[3](1,3)indolophane. Rapid access to a pentacyclic indoloid system. Org Lett 2002; 4:127-30. [PMID: 11772107 DOI: 10.1021/ol017014+] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] The title compound was synthesized concisely from indole. A 2-fold sequential hydroboration/Suzuki-Miyaura cross-coupling was employed to generate the cyclophane. When heated in N,N-diethylaniline, it underwent a transannular inverse electron demand Diels-Alder (IEDDA) reaction to form a pentacyclic product, which appears to be well suited as a precursor to a variety of indole alkaloids such as strychnine.
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Affiliation(s)
- Graham J Bodwell
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada, A1B 3X7.
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Dang Q, Liu Y, Sun Z. A tandem decarboxylation/Diels–Alder reaction of 5-amino-1-phenyl-4-pyrazolecarboxylic acid with 1,3,5-triazines. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)01822-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yu ZX, Dang Q, Wu YD. Aromatic dienophiles. 1. A theoretical study of an inverse-electron demand Diels-Alder reaction between 2-aminopyrrole and 1,3,5-triazine. J Org Chem 2001; 66:6029-36. [PMID: 11529728 DOI: 10.1021/jo010243p] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study is devoted to a detailed theoretical study of an inverse-electron demand Diels-Alder reaction (IDA) with 1,3,5-triazine as the diene and 2-aminopyrrole 1A(alpha) as the dienophile, which is a key step in a cascade reaction for the one-pot synthesis of purine analogues. Geometries were optimized with the B3LYP/6-31G* method and energies were evaluated with the MP2/6-311++G** method. This IDA reaction occurs through a stepwise mechanism, where the first step corresponds to the nucleophilic attack of 2-aminopyrrole to triazine to form a zwitterionic intermediate, which is in equilibrium with a neutral intermediate through a hydrogen transfer process, followed by a rate-determining ring-closure step. It is shown that the B3LYP method significantly overestimates the activation energy, whereas the MP2 method offers a reasonable activation barrier of 27.9 kcal/mol in the gas phase. The solvation effect has been studied by the PCM model. In DMSO, the calculated activation energy of the IDA reaction is decreased to 24.0 kcal/mol with a strong endothermicity of 17.4 kcal/mol due to the energy penalty of transforming two aromatic reactants into a nonaromatic IDA adduct. The possible stepwise [2+2] pathway is ruled out based on its higher activation and reaction energies than those of the [4+2] pathway. By comparing the IDA reactions of triazine to 2-aminopyrrole and pyrrole, we address two crucial roles of the alpha-amino substituent in lowering activation and reaction energies and controlling the reaction regiochemistry.
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Affiliation(s)
- Z X Yu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Dang Q, Liu Y, Erion MD. Efficient Synthesis of Purines and Purine Nucleosides via an Inverse Electron Demand Diels−Alder Reaction. J Am Chem Soc 1999. [DOI: 10.1021/ja9842316] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qun Dang
- Department of Medicinal Chemistry, Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, San Diego, California 92121
| | - Yan Liu
- Department of Medicinal Chemistry, Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, San Diego, California 92121
| | - Mark D. Erion
- Department of Medicinal Chemistry, Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, San Diego, California 92121
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