101
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Liu L, Floreancig P. Structurally and Stereochemically Diverse Tetrahydropyran Synthesis through Oxidative CH Bond Activation. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201000033] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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102
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Lin X, He Z, Zhu Y, Wang Y. DDQ-Mediated Tandem Synthesis of Functionalized Pyranocoumarins from 4-Hydroxycoumarins and 1,3-Diarylallylic Compounds. HETEROCYCLES 2010. [DOI: 10.3987/com-10-11906] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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103
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Jung HH, Floreancig PE. Mechanistic Analysis of Oxidative C-H Cleavages Using Inter- and Intramolecular Kinetic Isotope Effects. Tetrahedron 2009; 65:10830-10836. [PMID: 20640173 PMCID: PMC2904620 DOI: 10.1016/j.tet.2009.10.088] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A series of monodeuterated benzylic and allylic ethers were subjected to oxidative carbon-hydrogen bond cleavage to determine the impact of structural variation on intramolecular kinetic isotope effects in DDQ-mediated cyclization reactions. These values are compared to the corresponding intermolecular kinetic isotope effects that were accessed through subjecting mixtures of non-deuterated and dideuterated substrates to the reaction conditions. The results indicate that carbon-hydrogen bond cleavage is rate determining and that a radical cation is most likely a key intermediate in the reaction mechanism.
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Affiliation(s)
- Hyung Hoon Jung
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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104
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Liu L, Floreancig PE. Cyclization reactions through DDQ-mediated vinyl oxazolidinone oxidation. Org Lett 2009; 11:3152-5. [PMID: 19552390 DOI: 10.1021/ol901188q] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vinyl oxazolidinones react with DDQ to form alpha,beta-unsaturated acyliminium ions in a new method for forming electrophiles under oxidative conditions. Appended nucleophiles undergo 1,4-addition reactions with these intermediates to form cyclic vinyl oxazolidinones with good levels of diastereocontrol, highlighting a new approach to utilizing oxidative carbon-hydrogen bond functionalization to increase molecular complexity.
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Affiliation(s)
- Lei Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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105
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McQuaid KM, Long JZ, Sames D. C-H bond functionalization via hydride transfer: synthesis of dihydrobenzopyrans from ortho-vinylaryl akyl ethers. Org Lett 2009; 11:2972-5. [PMID: 19548698 PMCID: PMC2954889 DOI: 10.1021/ol900915p] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydride transfer initiated cyclization ("HT-cyclization") of aryl alkyl ethers, which leads to direct coupling of sp(3) C-H bonds and activated alkenes, is reported. Readily available salicylaldehyde derived ethers are converted in one step to dihydrobenzopyrans, an important class of heteroarenes frequently found in biologically active compounds. This process has not been previously reported, in contrast to known HT-cyclizations of the corresponding tert-amines ("tert-amino effect" reactions).
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Affiliation(s)
- Kevin M. McQuaid
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027
| | - Jonathan Z. Long
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027
| | - Dalibor Sames
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027
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106
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Yu B, Jiang T, Li J, Su Y, Pan X, She X. A Novel Prins Cyclization through Benzylic/Allylic C−H Activation. Org Lett 2009; 11:3442-5. [DOI: 10.1021/ol901291w] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Binxun Yu
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
| | - Tuo Jiang
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
| | - Junpeng Li
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
| | - Yingpeng Su
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
| | - Xinfu Pan
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
| | - Xuegong She
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou, 730000, P. R. China, and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physic, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
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107
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Tu W, Floreancig P. Oxidative Carbocation Formation in Macrocycles: Synthesis of the Neopeltolide Macrocycle. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200901489] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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108
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McQuaid KM, Sames D. C-H bond functionalization via hydride transfer: Lewis acid catalyzed alkylation reactions by direct intramolecular coupling of sp3 C-H bonds and reactive alkenyl oxocarbenium intermediates. J Am Chem Soc 2009; 131:402-3. [PMID: 19099474 DOI: 10.1021/ja806068h] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C-H bond functionalization enables strategically new approaches to the synthesis of complex organic molecules including biologically active compounds, research probes and functional organic materials. To address the shortcomings of transition metal catalyzed processes, we have developed a new approach to direct coupling of sp(3) C-H bonds and alkenes based on Lewis acid-promoted hydride transfer. Activation of alpha,beta-unsaturated aldehydes and ketones with Lewis acid triggers intramolecular hydride transfer, leading to a zwitterionic intermediate, which in turn undergoes ionic cyclization to afford the cyclic alkylation product. The scope of this method is expanded by the generation of alkenyl-oxocarbenium species as highly activated alkene intermediates capable of abstracting a hydride from unreactive carbon centers, including benzyl-, allyl-, and crotyl-ethers, as well as primary alkyl ethers, at room temperature. The alkenyl acetal and ketal substrates show dramatically faster rates of cyclization, as well as improved chemical yield and diastereoselectivity, compared to the corresponding carbonyl compounds. Furthermore, the use of boron trifluoride etherate as the Lewis acid and ethylene glycol as the organocatalyst provides a highly active catalytic system, presumably via the in situ formation of alkenyl-oxocarbenium intermediates, which eliminates the need for expensive transition metal Lewis acids or the preparation of ketal substrates. This binary catalytic system greatly improves the efficiency of the hydride transfer-initiated alkylation reactions.
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Affiliation(s)
- Kevin M McQuaid
- Department of Chemistry Columbia University, New York, New York 10027, USA
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109
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Tu W, Floreancig PE. Oxidative carbocation formation in macrocycles: synthesis of the neopeltolide macrocycle. Angew Chem Int Ed Engl 2009; 48:4567-71. [PMID: 19455526 PMCID: PMC2744605 DOI: 10.1002/anie.200901489] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Macrocyclic oxocarbenium ions can be formed from macrolactones that contain benzylic or allylic ether groups through oxidative carbon-hydrogen-bond activation mediated by 2,3-dichloro-4,5-dicyanoquinone (DDQ). The applicability of this efficient reaction to complex-molecule synthesis was demonstrated by its use in a brief formal synthesis of neopeltolide (see retrosynthetic scheme) to form the tetrahydropyrone ring.
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Affiliation(s)
- Wangyang Tu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA), Fax: (+1)412-624-8611, E-mail:
| | - Paul E. Floreancig
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA), Fax: (+1)412-624-8611, E-mail:
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110
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Benfatti F, Capdevila MG, Zoli L, Benedetto E, Cozzi PG. Catalytic stereoselective benzylic C–H functionalizations by oxidative C–H activation and organocatalysis. Chem Commun (Camb) 2009:5919-21. [DOI: 10.1039/b910185c] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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