1
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Forsythe NP, Mize ER, Kashiwagi GA, Demchenko AV. Expedient Synthesis of Superarmed Glycosyl Donors via Oxidative Thioglycosidation of Glycals. SYNTHESIS-STUTTGART 2024; 56:1147-1156. [PMID: 38655286 PMCID: PMC11034933 DOI: 10.1055/a-2183-0175] [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] [Indexed: 04/26/2024]
Abstract
Superarmed glycosyl donors have higher reactivity compared to their perbenzylated armed counterparts. Generally, the 2-O- benzoyl-3,4,6-tri-O-benzyl protecting group pattern gives rise to increased reactivity due to an O-2/O-5 cooperative effect. Despite having a high reactivity profile and applicability in many expeditious strategies for glycan synthesis, regioselective introduction of the superarming protecting group pattern is tedious for most sugar series. Reported herein is a streamlined synthetic route to yield superarmed glycosyl donors of the d-gluco and d-galacto series equipped with an ethylthio, phenylthio, p-tolylthio, benzoxazol-2-ylthio, O-allyl, or O-pentenyl anomeric leaving group. This streamlined approach was made possible due to the refinement of the oxidative thioglycosylation reaction of the respective glucal and galactal precursors. The applicability of this approach to the direct formation of disaccharides is also showcased.
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Affiliation(s)
- Nicholas P Forsythe
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave, St. Louis, MO 63103, USA
| | - Emma R Mize
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave, St. Louis, MO 63103, USA
| | - Gustavo A Kashiwagi
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave, St. Louis, MO 63103, USA
| | - Alexei V Demchenko
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave, St. Louis, MO 63103, USA
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2
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Mukherji A, Rotta MKV, Sarmah BK, Kancharla PK. Influence of Various Silyl Protecting Groups on Stereoselective 2-Deoxyrhamnosylation. J Org Chem 2023; 88:245-260. [PMID: 36524596 DOI: 10.1021/acs.joc.2c02285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The influence of various silyl protecting groups on 2-deoxyrhamnosylation using 2-deoxyrhamnosyl acetates, thioglycosides, and (p-methoxyphenyl)vinylbenzoate (PMPVB) donors has been presented. C-Glycosylation reactions reveal that tert-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), and tert-butyldiphenylsilyl (TBDPS) silyl protected rhamnosyl oxocarbenium ions have no facial selectivity except for the conformationally (4H3) locked tetraisopropyldisiloxane (TIPDS) protected rhamnose donor, which provides complete α-selectivity. However, TBDPS protected rhamnosyl donors are found to be superior protecting groups for α-stereoselective O-glycosylation reactions with various acceptors. The observed results are found consistent across donors and donor activation conditions. Most importantly, the study was conducted at room temperature unlike the other energy-intensive low-temperature studies and was bound to have more practical utility. The outcomes have been explained using kinetic and thermodynamic analyses.
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Affiliation(s)
- Ananya Mukherji
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Mahendra K V Rotta
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Bikash K Sarmah
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Pavan K Kancharla
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
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3
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Singh Y, Geringer SA, Demchenko AV. Synthesis and Glycosidation of Anomeric Halides: Evolution from Early Studies to Modern Methods of the 21st Century. Chem Rev 2022; 122:11701-11758. [PMID: 35675037 PMCID: PMC9417321 DOI: 10.1021/acs.chemrev.2c00029] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Advances in synthetic carbohydrate chemistry have dramatically improved access to common glycans. However, many novel methods still fail to adequately address challenges associated with chemical glycosylation and glycan synthesis. Since a challenge of glycosylation has remained, scientists have been frequently returning to the traditional glycosyl donors. This review is dedicated to glycosyl halides that have played crucial roles in shaping the field of glycosciences and continue to pave the way toward our understanding of chemical glycosylation.
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Affiliation(s)
- Yashapal Singh
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Scott A Geringer
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Alexei V Demchenko
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
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4
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Casali E, Othman ST, Dezaye AA, Chiodi D, Porta A, Zanoni G. Highly Stereoselective Glycosylation Reactions of Furanoside Derivatives via Rhenium (V) Catalysis. J Org Chem 2021; 86:7672-7686. [PMID: 34033490 PMCID: PMC8279489 DOI: 10.1021/acs.joc.1c00706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel approach for the formation of anomeric carbon-functionalized furanoside systems was accomplished through the employment of an oxo-rhenium catalyst. The transformation boasts a broad range of nucleophiles including allylsilanes, enol ethers, and aromatics in addition to sulfur, nitrogen, and hydride donors, able to react with an oxocarbenium ion intermediate derived from furanosidic structures. The excellent stereoselectivities observed followed the Woerpel model, ultimately providing 1,3-cis-1,4-trans systems. In the case of electron-rich aromatic nucleophiles, an equilibration occurs at the anomeric center with the selective formation of 1,3-trans-1,4-cis systems. This anomalous result was rationalized through density functional theory calculations. Different oxocarbenium ions such as those derived from dihydroisobenzofuran, pyrrolidine, and oxazolidine heterocycles can also be used as a substrate for the oxo-Re-mediated allylation reaction.
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Affiliation(s)
- Emanuele Casali
- Department of Chemistry, University of Pavia, Viale Taramelli, 12, Pavia 27100, Italy
| | - Sirwan T Othman
- Department of Chemistry, College of Science, Salahaddin University-Erbil, Erbil 44002, Iraq
| | - Ahmed A Dezaye
- International University of Erbil, Newroz Street, Erbil-Kurdistan 44001, Iraq
| | - Debora Chiodi
- Department of Chemistry, University of Pavia, Viale Taramelli, 12, Pavia 27100, Italy
| | - Alessio Porta
- Department of Chemistry, University of Pavia, Viale Taramelli, 12, Pavia 27100, Italy
| | - Giuseppe Zanoni
- Department of Chemistry, University of Pavia, Viale Taramelli, 12, Pavia 27100, Italy
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5
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Wang L, Zhou P, Lin Q, Dong S, Liu X, Feng X. Chiral Fe(ii) complex catalyzed enantioselective [1,3] O-to-C rearrangement of alkyl vinyl ethers and synthesis of chromanols and beyond. Chem Sci 2020; 11:10101-10106. [PMID: 34094271 PMCID: PMC8162448 DOI: 10.1039/d0sc04340k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/07/2020] [Indexed: 12/28/2022] Open
Abstract
A highly efficient enantioselective [1,3] O-to-C rearrangement of racemic vinyl ethers that operates under mild conditions was developed. This method with chiral ferrous complex catalyst provided an efficient access to a wide range of chromanols with high yields and excellent enantioselectivities. In addition, an important urological drug (R)-tolterodine and others were easily obtained after simple transformations.
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Affiliation(s)
- Lifeng Wang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
| | - Pengfei Zhou
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
| | - Qianchi Lin
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
| | - Shunxi Dong
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
| | - Xiaohua Liu
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 China
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6
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Kolyvanov NA, Oparina LA, Tarasova OA, Albanov AI, Gusarova NK, Trofimov BA. Pd-catalyzed rearrangement of ferrocenylalkyl vinyl ethers to the related aldehydes and ketones. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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7
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Alonso-Gil S. Mimicking the transition state of reactions of glycoside hydrolases: Updating the conformational space of the oxocarbenium cation. J Carbohydr Chem 2020. [DOI: 10.1080/07328303.2020.1766481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Santiago Alonso-Gil
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague 8, Czech Republic
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8
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Chen Y, Liu Y, Li Z, Dong S, Liu X, Feng X. Tandem Insertion–[1,3]‐Rearrangement: Highly Enantioselective Construction of α‐Aminoketones. Angew Chem Int Ed Engl 2020; 59:8052-8056. [DOI: 10.1002/anie.201914645] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/28/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Yushuang Chen
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Yun Liu
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Zhaojing Li
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Shunxi Dong
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Xiaohua Liu
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
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9
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Chen Y, Liu Y, Li Z, Dong S, Liu X, Feng X. Tandem Insertion–[1,3]‐Rearrangement: Highly Enantioselective Construction of α‐Aminoketones. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914645] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yushuang Chen
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Yun Liu
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Zhaojing Li
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Shunxi Dong
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Xiaohua Liu
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & TechnologyMinistry of EducationCollege of ChemistrySichuan University Chengdu 610064 China
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10
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Panza M, Civera M, Yasomanee JP, Belvisi L, Demchenko AV. Bromine-Promoted Glycosidation of Conformationally Superarmed Thioglycosides. Chemistry 2019; 25:11831-11836. [PMID: 31286579 DOI: 10.1002/chem.201901969] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/03/2019] [Indexed: 01/24/2023]
Abstract
Presented herein is a study of the conformation and reactivity of highly reactive thioglycoside donors. The structural studies have been conducted using NMR spectroscopy and computational methods. The reactivity of these donors has been investigated in bromine-promoted glycosylations of aliphatic and sugar alcohols. Swift reaction times, high yields, and respectable 1,2-cis stereoselectivity were observed in a majority of these glycosylations.
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Affiliation(s)
- Matteo Panza
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
| | - Monica Civera
- Department of Chemistry, University of Milan, 20133, Milan, Italy
| | - Jagodige P Yasomanee
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
| | - Laura Belvisi
- Department of Chemistry, University of Milan, 20133, Milan, Italy
| | - Alexei V Demchenko
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
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11
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Panza M, Pistorio SG, Stine KJ, Demchenko AV. Automated Chemical Oligosaccharide Synthesis: Novel Approach to Traditional Challenges. Chem Rev 2018; 118:8105-8150. [PMID: 29953217 PMCID: PMC6522228 DOI: 10.1021/acs.chemrev.8b00051] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Advances in carbohydrate chemistry have certainly made common oligosaccharides much more accessible. However, many current methods still rely heavily upon specialized knowledge of carbohydrate chemistry. The application of automated technologies to chemical and life science applications such as genomics and proteomics represents a vibrant field. These automated technologies also present opportunities for their application to organic synthesis, including that of the synthesis of oligosaccharides. However, application of automated methods to the synthesis of carbohydrates is an underdeveloped area as compared to other classes of biomolecules. The overarching goal of this review article is to present the advances that have been made at the interface of carbohydrate chemistry and automated technology.
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Affiliation(s)
- Matteo Panza
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Salvatore G. Pistorio
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Keith J. Stine
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Alexei V. Demchenko
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
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12
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Hernández-Torres G, Mateo J, Colobert F, Urbano A, Carreño MC. Synthesis of Medium-Sized 2,ω-cis-Disubstituted Cyclic Ethers by Reductive Cyclization of Hydroxy Ketones. ChemistrySelect 2016. [DOI: 10.1002/slct.201601161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Gloria Hernández-Torres
- Departamento de Química Orgánica (Módulo 01), Fac. Ciencias; Universidad Autónoma de Madrid; c/ Francisco Tomás y Valiente 7, Cantoblanco 28049- Madrid Spain
| | - Julio Mateo
- Departamento de Química Orgánica (Módulo 01), Fac. Ciencias; Universidad Autónoma de Madrid; c/ Francisco Tomás y Valiente 7, Cantoblanco 28049- Madrid Spain
| | - FranÇoise Colobert
- Laboratoire de Synthèse et Catalyse Asymétrique; Université de Strasbourg (ECPM), UMR CNRS 7509; 25 rue Becquerel 67087 Strasbourg Cedex 02 France
| | - Antonio Urbano
- Departamento de Química Orgánica (Módulo 01), Fac. Ciencias; Universidad Autónoma de Madrid; c/ Francisco Tomás y Valiente 7, Cantoblanco 28049- Madrid Spain
| | - M. Carmen Carreño
- Departamento de Química Orgánica (Módulo 01), Fac. Ciencias; Universidad Autónoma de Madrid; c/ Francisco Tomás y Valiente 7, Cantoblanco 28049- Madrid Spain
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13
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Gil-Negrete JM, Pérez Sestelo J, Sarandeses LA. Transition-Metal-Free Cross-Coupling of Indium Organometallics with Chromene and Isochroman Acetals Mediated by BF3·OEt2. Org Lett 2016; 18:4316-9. [PMID: 27530143 DOI: 10.1021/acs.orglett.6b02058] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A transition-metal-free coupling of triorganoindium reagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3·OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respectively, in good yields. The reactions proceed with a variety of triorganoindium reagents (aryl, heteroaryl, alkynyl, alkenyl, alkyl) using only 50 mol % of the organometallic, thus demonstrating the efficiency of these species. Preliminary mechanistic studies indicate the formation of an oxocarbenium ion intermediate in the presence of the Lewis acid.
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Affiliation(s)
- José M Gil-Negrete
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , E-15071 A Coruña, Spain
| | - José Pérez Sestelo
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , E-15071 A Coruña, Spain
| | - Luis A Sarandeses
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , E-15071 A Coruña, Spain
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14
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Prévost M, Dostie S, Waltz MÈ, Guindon Y. Investigation of diastereoselective acyclic α-alkoxydithioacetal substitutions involving thiacarbenium intermediates. J Org Chem 2014; 79:10504-25. [PMID: 25280088 DOI: 10.1021/jo502181a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Reported herein is an experimental and theoretical study that elucidates why silylated nucleobase additions to acyclic α-alkoxythiacarbenium intermediates proceed with high 1,2-syn stereocontrol (anti-Felkin-Anh), which is opposite to what would be expected with corresponding activated aldehydes. The acyclic thioaminals formed undergo intramolecular cyclizations to provide nucleoside analogues with anticancer and antiviral properties. The factors influencing the selectivity of the substitution reaction have been examined thoroughly. Halothioether species initially form, ionize in the presence (low dielectric media) or absence (higher dielectric media) of the nucleophile, and react through SN2-like transition structures (TS A and D), where the α-alkoxy group is gauche to the thioether moiety. An important, and perhaps counterintuitive, observation in this work was that calculations done in the gas phase or low dielectric media (toluene) are essential to locate the product- and rate-determining transition structures (C-N bond formation) that allow the most reasonable prediction of selectivity and isotope effects for more polar solvents (THF, MeCN). The ΔΔG(⧧) (G(TSA-TSD)) obtained in silico are consistent with the preferential formation of 1,2-syn product and with the trends of stereocontrol displayed by 2,3-anti and 2,3-syn α,β-bis-alkoxydithioacetals.
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Affiliation(s)
- Michel Prévost
- Bio-Organic Chemistry Laboratory, Institut de Recherches Cliniques de Montréal (IRCM) , Montréal, Québec, H2W 1R7, Canada
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15
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Manabe S, Ito Y. Pyranosides with 2,3-trans carbamate groups: exocyclic or endocyclic cleavage reaction? CHEM REC 2014; 14:502-15. [PMID: 24914008 DOI: 10.1002/tcr.201402004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Indexed: 12/28/2022]
Abstract
Pyranosides with 2,3-trans carbamate groups exhibit high 1,2-cis selectivity in glycosylation reactions. Using glycosyl donors with N-benzyl 2,3-trans carbamate groups, an anti-Helicobacter pylori oligosaccharide was synthesized in an efficient manner. Moreover, pyranosides with 2,3-trans carbamate groups readily undergo anomerization from the β to the α configuration under mild acidic conditions via endocyclic cleavage. Acyclic cations generated during the endocyclic cleavage reaction were captured using reduction and intramolecular Friedel-Crafts reaction. By exploiting this anomerization, multiply aligned 1,2-trans glycosyl bonds can be transformed to 1,2-cis glycosyl bonds in a single operation.
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Affiliation(s)
- Shino Manabe
- RIKEN, Synthetic Cellular Chemistry Laboratory, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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16
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17
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Cañeque T, Truscott FM, Rodriguez R, Maestri G, Malacria M. Electrophilic activation of allenenes and allenynes: analogies and differences between Brønsted and Lewis acid activation. Chem Soc Rev 2014; 43:2916-26. [DOI: 10.1039/c4cs00023d] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This review focuses on electrophilic activation of allenes by an acid. Key mechanistic features are presented together with recent synthetic applications.
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Affiliation(s)
- T. Cañeque
- Institut de Chimie des Substances Naturelles
- ICNS-CNRS UPR2301
- Gif/Yvette Cedex 91198, France
| | - F. M. Truscott
- Institut de Chimie des Substances Naturelles
- ICNS-CNRS UPR2301
- Gif/Yvette Cedex 91198, France
| | - R. Rodriguez
- Institut de Chimie des Substances Naturelles
- ICNS-CNRS UPR2301
- Gif/Yvette Cedex 91198, France
| | - G. Maestri
- Institut de Chimie des Substances Naturelles
- ICNS-CNRS UPR2301
- Gif/Yvette Cedex 91198, France
- Dipartimento di Chimica
- Università degli Studi di Parma
| | - M. Malacria
- Institut de Chimie des Substances Naturelles
- ICNS-CNRS UPR2301
- Gif/Yvette Cedex 91198, France
- Institut Parisienne de Chimie Moleculaire
- UPMC Université Paris 06
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18
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19
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20
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Tayama E, Horikawa K, Iwamoto H, Hasegawa E. 1,4-Elimination/Brønsted acid catalyzed aza-Ferrier reaction sequence as an entry to β-amino-β,γ-unsaturated aldehydes. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.01.088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Ranade SC, Demchenko AV. Mechanism of Chemical Glycosylation: Focus on the Mode of Activation and Departure of Anomeric Leaving Groups. J Carbohydr Chem 2013. [DOI: 10.1080/07328303.2012.749264] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Sneha C. Ranade
- a Department of Chemistry and Biochemistry , University of Missouri , St. Louis , MO , 63121 , USA
| | - Alexei V. Demchenko
- a Department of Chemistry and Biochemistry , University of Missouri , St. Louis , MO , 63121 , USA
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22
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Kumar R, Whitfield DM. Could Diastereoselectivity in the Presence of O-2 Chiral Nonparticipating Groups Be an Indicator of Glycopyranosyl Oxacarbenium Ions in Glycosylation Reactions? J Org Chem 2012; 77:3724-39. [DOI: 10.1021/jo202563f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Rishi Kumar
- National Research Council, Institute for Biological Sciences, 100 Sussex Drive, Ottawa, Ontario,
Canada K1A 0R6
| | - Dennis M. Whitfield
- National Research Council, Institute for Biological Sciences, 100 Sussex Drive, Ottawa, Ontario,
Canada K1A 0R6
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23
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Wurst JM, Liu G, Tan DS. Hydrogen-bonding catalysis and inhibition by simple solvents in the stereoselective kinetic epoxide-opening spirocyclization of glycal epoxides to form spiroketals. J Am Chem Soc 2011; 133:7916-25. [PMID: 21539313 DOI: 10.1021/ja201249c] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mechanistic investigations of a MeOH-induced kinetic epoxide-opening spirocyclization of glycal epoxides have revealed dramatic, specific roles for simple solvents in hydrogen-bonding catalysis of this reaction to form spiroketal products stereoselectively with inversion of configuration at the anomeric carbon. A series of electronically tuned C1-aryl glycal epoxides was used to study the mechanism of this reaction based on differential reaction rates and inherent preferences for S(N)2 versus S(N)1 reaction manifolds. Hammett analysis of reaction kinetics with these substrates is consistent with an S(N)2 or S(N)2-like mechanism (ρ = -1.3 vs ρ = -5.1 for corresponding S(N)1 reactions of these substrates). Notably, the spirocyclization reaction is second-order dependent on MeOH, and the glycal ring oxygen is required for second-order MeOH catalysis. However, acetone cosolvent is a first-order inhibitor of the reaction. A transition state consistent with the experimental data is proposed in which one equivalent of MeOH activates the epoxide electrophile via a hydrogen bond while a second equivalent of MeOH chelates the side-chain nucleophile and glycal ring oxygen. A paradoxical previous observation that decreased MeOH concentration leads to increased competing intermolecular methyl glycoside formation is resolved by the finding that this side reaction is only first-order dependent on MeOH. This study highlights the unusual abilities of simple solvents to act as hydrogen-bonding catalysts and inhibitors in epoxide-opening reactions, providing both stereoselectivity and discrimination between competing reaction manifolds. This spirocyclization reaction provides efficient, stereocontrolled access to spiroketals that are key structural motifs in natural products.
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Affiliation(s)
- Jacqueline M Wurst
- Tri-Institutional Training Program in Chemical Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 422, New York, New York 10065, USA
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Hernández-Torres G, Carreño MC, Urbano A, Colobert F. The Effect of Sulfoxides on the Stereoselective Construction of Tetrahydrofurans: Total Synthesis of (+)-Goniothalesdiol. Chemistry 2010; 17:1283-93. [DOI: 10.1002/chem.201002637] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Indexed: 11/09/2022]
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25
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Boto A, Hernández D, Hernández R. One-Pot Conversion of Proline Derivatives into Iodinated Iminosugar-Based Nucleosides, Useful Precursors of Highly Functionalized Nucleoside Analogues. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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26
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Prévost M, St-Jean O, Guindon Y. Synthesis of 1′,2′-cis-Nucleoside Analogues: Evidence of Stereoelectronic Control for SN2 Reactions at the Anomeric Center of Furanosides. J Am Chem Soc 2010; 132:12433-9. [DOI: 10.1021/ja104429y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michel Prévost
- Institut de Recherches Cliniques de Montréal (IRCM), Bio-organic Chemistry Laboratory, 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7, Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Québec, Canada H3C 3J7, and Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Olivier St-Jean
- Institut de Recherches Cliniques de Montréal (IRCM), Bio-organic Chemistry Laboratory, 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7, Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Québec, Canada H3C 3J7, and Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Yvan Guindon
- Institut de Recherches Cliniques de Montréal (IRCM), Bio-organic Chemistry Laboratory, 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7, Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Québec, Canada H3C 3J7, and Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
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27
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Boto A, Hernández D, Hernández R. One-Pot Synthesis of Azanucleosides from Proline Derivatives - Stereoselectivity in Sequential Processes. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000360] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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28
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Rhoad JS, Cagg BA, Carver PW. Scanning the Potential Energy Surface of Furanosyl Oxocarbenium Ions: Models for Reactive Intermediates in Glycosylation Reactions. J Phys Chem A 2010; 114:5180-6. [DOI: 10.1021/jp9100448] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Jonathan S. Rhoad
- Department of Chemistry, Missouri Western State University, 4525 Downs Drive, St. Joseph, Missouri 64507
| | - Brett A. Cagg
- Department of Chemistry, Missouri Western State University, 4525 Downs Drive, St. Joseph, Missouri 64507
| | - Patrick W. Carver
- Department of Chemistry, Missouri Western State University, 4525 Downs Drive, St. Joseph, Missouri 64507
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29
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Krumper JR, Salamant WA, Woerpel KA. Correlations between nucleophilicities and selectivities in the substitutions of tetrahydropyran acetals. J Org Chem 2010; 74:8039-50. [PMID: 19813702 DOI: 10.1021/jo901639b] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selectivities that deviate from S(N)1 stereoelectronic models in the nucleophilic substitutions of tetrahydropyran acetals were investigated. When weak nucleophiles were employed, stereoselectivities conformed to known S(N)1 stereoelectronic models. In contrast, stereoselectivities in the substitutions of acetals with strong nucleophiles depended on reaction conditions. Erosions in selectivities were observed when strong nucleophiles were employed in the absence of coordinating counterions. These erosions in selectivities are attributed to rates of nucleophilic additions to oxocarbenium ion intermediates that approach the diffusion limit. When triflate counterions were present, however, S(N)2-like pathways became accessible with strong nucleophiles. In most cases examined, the major stereoisomers formed from reactions that proceeded through S(N)2-like pathways were opposite to the major stereoisomers formed from the analogous reactions that proceeded through S(N)1 pathways.
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Affiliation(s)
- Jennifer R Krumper
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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30
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Friestad GK, Lee HJ. Trans-2,5-Disubstituted Tetrahydrofurans via Addition of Carbon Nucleophiles to the Strained Bicyclic Acetal 2,7-Dioxabicyclo[2.2.1]heptane. Org Lett 2009; 11:3958-61. [DOI: 10.1021/ol901613k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Hye Jin Lee
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
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31
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Computational studies of the role of glycopyranosyl oxacarbenium ions in glycobiology and glycochemistry. Adv Carbohydr Chem Biochem 2009; 62:83-159. [PMID: 19501705 DOI: 10.1016/s0065-2318(09)00004-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Enantiopure alkaloid analogues and iminosugars from proline derivatives: stereocontrol in sequential processes. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.04.082] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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33
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Krumper JR, Salamant WA, Woerpel KA. Continuum of mechanisms for nucleophilic substitutions of cyclic acetals. Org Lett 2008; 10:4907-10. [PMID: 18844363 DOI: 10.1021/ol8019956] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of nucleophile strength on diastereoselectivity in the nucleophilic substitution of cyclic acetals was explored. Stereoselectivity remained constant and high as nucleophilicity increased until a threshold value was reached. Beyond this point, however, selection of Lewis acid determined whether stereochemical inversion or erosion was observed.
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Affiliation(s)
- Jennifer R Krumper
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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34
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Banaag AR, Tius MA. Traceless chiral auxiliaries for the allene ether Nazarov cyclization. J Org Chem 2008; 73:8133-41. [PMID: 18808186 DOI: 10.1021/jo801503c] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The key stereochemical factors that determine transfer of asymmetry from the chiral auxiliary to the cyclopentenone in the allene ether version of the Nazarov reaction have been elucidated. On the basis of the new insights into the mechanism, two highly effective chiral auxiliaries were designed and prepared.
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Affiliation(s)
- April R Banaag
- University of Hawaii, Chemistry Department, Honolulu, Hawaii 96822, USA
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35
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Tayama E, Otoyama S, Isaka W. Brønsted acid catalyzed regioselective aza-Ferrier reaction: a novel synthetic method for α-(N-Boc-2-pyrrolidinyl) aldehydes. Chem Commun (Camb) 2008:4216-8. [DOI: 10.1039/b806492j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Nasveschuk CG, Rovis T. The [1, 3] O-to-C rearrangement: opportunities for stereoselective synthesis. Org Biomol Chem 2007; 6:240-54. [PMID: 18174990 DOI: 10.1039/b714881j] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The relay of stereochemistry of a breaking C-O bond into a forming C-C bond is well-known in the context of [3, 3] sigmatropic shifts; however, this useful strategy is less well-known in other types of molecular rearrangements. Though the first successful example of a [1, 3] O-to-C rearrangement was reported more than 100 years ago, this class of reactions has received less attention than its [3, 3] counterpart. This perspective analyzes the various methods used for the activation and [1, 3] rearrangement of vinyl ethers with an emphasis on mechanism and applications to stereoselective synthesis. We also highlight our own contributions to this area.
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37
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Banaag AR, Tius MA. Design of chiral auxiliaries for the allene ether nazarov cyclization. J Am Chem Soc 2007; 129:5328-9. [PMID: 17425314 PMCID: PMC2533689 DOI: 10.1021/ja069342g] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- April R. Banaag
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
| | - Marcus A. Tius
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
- Cancer Research Center of Hawaii, 1236 Lauhala Street, Honolulu Hawaii 96813
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38
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Meek SJ, Harrity JP. O→C rearrangements: a powerful strategy for the synthesis of functionalised carbocycles. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.01.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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39
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Ionescu AR, Whitfield DM, Zgierski MZ, Nukada T. Investigations into the role of oxacarbenium ions in glycosylation reactions by ab initio molecular dynamics. Carbohydr Res 2006; 341:2912-20. [PMID: 17069777 DOI: 10.1016/j.carres.2006.09.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 09/14/2006] [Accepted: 09/21/2006] [Indexed: 10/24/2022]
Abstract
We present a constrained ab initio molecular dynamics method that allows the modeling of the conformational interconversions of glycopyranosyl oxacarbenium ions. The model was successfully tested by estimating the barriers to ring inversion for two 4-substituted tetrahydropyranosyl oxacarbenium ions. The model was further extended to predict the pathways that connect the (4)H(3) half-chair conformation of 2,3,4,6-tetra-O-methyl-d-glucopyranosyl cation to its inverted (5)S(1) conformation and the (4)H(3) half-chair conformation of 2,3,4,6-tetra-O-methyl-d-mannopyranosyl cation to its inverted (3)E conformation. The modeled interconversion pathways reconcile a large body of experimental work on the acid-catalyzed hydrolysis of glycosides and the mechanisms of a number of glucosidases and mannosidases.
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Affiliation(s)
- Andrei R Ionescu
- Steacie Institute for Molecular Sciences, NRC Canada, 100 Sussex Drive, Ottawa, Ont., Canada
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40
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de Godoy LAF, Camilo NS, Pilli RA. Addition of carbon nucleophiles to cyclic N-acyliminium and oxocarbenium ions under solvent-free conditions. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.09.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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41
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Tayama E, Isaka W. Regio- and Stereoselective Ferrier Reaction of O-1,3-Dienyl Acetals Promoted by Organoaluminum Complexes. Org Lett 2006; 8:5437-9. [PMID: 17107041 DOI: 10.1021/ol062042j] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Ferrier reaction of O-1,3-dienyl acetals promoted by organoaluminum complexes such as methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD) is shown to proceed with a high degree of regio- and stereoselectivity to afford the corresponding alpha-alkenyl-substituted beta-alkoxy aldehydes in good yields. The mechanistic origin of the high regiocontrolling ability of MAD is elucidated. This method, coupled with the easy availability of the requisite substrates, expands the synthetic scope of the Ferrier reaction. [reaction: see text].
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Affiliation(s)
- Eiji Tayama
- Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
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42
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Shenoy SR, Smith DM, Woerpel KA. Nucleophilic Additions of Trimethylsilyl Cyanide to Cyclic Oxocarbenium Ions: Evidence for the Loss of Stereoselectivity at the Limits of Diffusion Control. J Am Chem Soc 2006; 128:8671-7. [PMID: 16802834 DOI: 10.1021/ja061110u] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The limitations of stereoelectronic models in assessing the stereoselective nucleophilic substitution reactions of cyclic oxocarbenium ions at high reaction rates are discussed. Evidence is provided suggesting that the diastereoselectivity of nucleophilic substitution reactions is attenuated at the limits of diffusion control. The low diastereoselectivities observed in the reactions of trimethylsilyl cyanide with five- and six-membered ring oxocarbenium ions are attributed to the high reactivity of the nucleophile and its reactions with these electrophiles at diffusion control rates.
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Affiliation(s)
- Siddhartha R Shenoy
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-2025, USA
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43
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Frein JD, Rovis T. Surveying approaches to the formation of carbon-carbon bonds between a pyran and an adjacent ring. Tetrahedron 2006; 62:4573-4583. [PMID: 17710219 PMCID: PMC1950123 DOI: 10.1016/j.tet.2006.02.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have examined several methods for the stereoselective formation of carbon-carbon bonds between contiguous rings where a stereogenic center is already present. The approaches investigated were a [1,3] oxygen to carbon rearrangement of cyclic vinyl acetals, an intermolecular enolsilane addition into an in situ generated oxocarbenium ion, an intramolecular conjugate addition of tethered alkoxy enones, and epimerization of several α-pyranyl cycloalkanones. These routes have been found to be complementary in several cases and have enabled formation of both the trans:anti and cis:anti stereoisomers in good to excellent yields and varying diastereoselectivities. We have proven C2-C2' relative stereochemistry of 1-2 via a chemical correlation.
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Affiliation(s)
- Jeffrey D. Frein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Tomislav Rovis
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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44
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Lucero CG, Woerpel KA. StereoselectiveC-Glycosylation Reactions of Pyranoses: The Conformational Preference and Reactions of the Mannosyl Cation. J Org Chem 2006; 71:2641-7. [PMID: 16555815 DOI: 10.1021/jo0522963] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A systematic study of C-glycosylations of acetals related to mannose and other pyranoses was conducted. The C-5 alkoxyalkyl group provides only a modest influence on stereoselectivity. On the other hand, studies of pentopyranoses bearing alkoxy groups at C-2, C-3, and C-4 showed that the alkoxy groups exerted powerful influences on selectivity. In the case of mannose, the high alpha selectivity observed with C-mannosylation was reversed to high beta selectivity if the C-5 alkoxyalkyl group were removed. An analysis of the conformational preferences of the intermediate oxocarbenium ions, including the mannosyl cation, as well as consideration of steric effects that develop in the transition states for nucleophilic attack provide explanations for these phenomena.
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Affiliation(s)
- Claudia G Lucero
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
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45
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Larsen CH, Ridgway BH, Shaw JT, Smith DM, Woerpel KA. Stereoselective C-glycosylation reactions of ribose derivatives: electronic effects of five-membered ring oxocarbenium ions. J Am Chem Soc 2006; 127:10879-84. [PMID: 16076193 DOI: 10.1021/ja0524043] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The factors controlling the highly alpha-selective C-glycosylation of ribose derivatives were determined by examining the stereoselective reactions of 18 ribose analogues differing in substitution at C-2, C-3, and C-4. The lowest energy conformers of the intermediate oxocarbenium ions display the C-3 alkoxy group in a pseudoaxial orientation to maximize electrostatic effects. To a lesser extent, the C-2 substituent prefers a pseudoequatorial position, and the alkyl group at C-4 has little influence on conformational preferences. In all cases, the product was formed by stereoelectronically preferred inside attack on the lowest energy conformer.
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Affiliation(s)
- Catharine H Larsen
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-2025, USA
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46
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Smith DM, Woerpel KA. Electrostatic interactions in cations and their importance in biology and chemistry. Org Biomol Chem 2006; 4:1195-201. [PMID: 16557303 DOI: 10.1039/b600056h] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrostatic effects exert strongly stabilizing influences on cations, in many cases controlling the conformational preferences of these cations. The lowest energy conformers are ones where the positive charge is brought closest to substituents bearing partial negative charges. These conformational biases, along with stereoelectronic effects, can control the stereoselectivity of reactions involving carbocationic intermediates.
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Affiliation(s)
- Deborah M Smith
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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47
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Mechanisms for nucleophilic aliphatic substitution at glycosides. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2006. [DOI: 10.1016/s0065-3160(06)41005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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48
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A tandem C–H insertion—acetal cleavage sequence: stereocontrolled synthesis of substituted tetrahydrofurans. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.08.082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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