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Borowski D, Oechsner RM, Jürgens E, Ziegler T. Carbohydrate-Derived 3,2-Enolones in the Base-Catalyzed Rearrangement to Highly Functionalized C
4-Quaternary 4-Hydroxy-2-cyclopentenones. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Daniel Borowski
- Institute of Organic Chemistry; University of Tuebingen; Auf der Morgenstelle 18 72076 Tuebingen Germany
| | - Regina M. Oechsner
- Institute of Organic Chemistry; University of Tuebingen; Auf der Morgenstelle 18 72076 Tuebingen Germany
| | - Eva Jürgens
- Institute of Inorganic Chemistry; University of Tuebingen; Auf der Morgenstelle 18 72076 Tuebingen Germany
| | - Thomas Ziegler
- Institute of Organic Chemistry; University of Tuebingen; Auf der Morgenstelle 18 72076 Tuebingen Germany
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Geng X, Wang L, Gu G, Guo Z. Synthesis of a trisaccharide repeating unit of the O-antigen from Burkholderia anthina and its dimer. Carbohydr Res 2016; 427:13-20. [DOI: 10.1016/j.carres.2016.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/24/2016] [Accepted: 03/25/2016] [Indexed: 12/29/2022]
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3
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Jacob S, Brooks JL, Frontier AJ. No acid required: 4π and 6π electrocyclization reactions of dienyl diketones for the synthesis of cyclopentenones and 2H-Pyrans. J Org Chem 2014; 79:10296-302. [PMID: 25325706 PMCID: PMC4227568 DOI: 10.1021/jo501914w] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Indexed: 12/19/2022]
Abstract
The 1,6-conjugate addition of nucleophiles to dienyl diketones produces either cyclopentenone or 2H-pyran products with high selectivity through either Nazarov (4π) or 6π electrocyclization, respectively. The outcome of the reaction is dependent upon the nature of the nucleophile used. Nucleophiles that are anionic or easily deprotonated exclusively produce cyclopentenones via Nazarov cyclization, whereas the neutral nucleophile DABCO promotes 6π cyclization to afford 2H-pyrans. Experimental evidence is presented for both retro-4π and -6π electrocyclization in these systems, lending support to the bifurcated mechanistic hypothesis proposed for these cyclizations.
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Affiliation(s)
- Steven
D. Jacob
- Department of Chemistry, University of
Rochester, Rochester, New York 14627, United
States
| | - Joshua L. Brooks
- Department of Chemistry, University of
Rochester, Rochester, New York 14627, United
States
| | - Alison J. Frontier
- Department of Chemistry, University of
Rochester, Rochester, New York 14627, United
States
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Spencer WT, Vaidya T, Frontier AJ. Beyond the Divinyl Ketone: Innovations in the Generation and Nazarov Cyclization of Pentadienyl Cation Intermediates. European J Org Chem 2013; 2013:10.1002/ejoc.201300134. [PMID: 24348092 PMCID: PMC3862358 DOI: 10.1002/ejoc.201300134] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Indexed: 11/09/2022]
Abstract
The requirement for new strategies for synthesizing five-membered carbocycles has driven an expansion in the study of the Nazarov cyclization. This renewed interest in the reaction has led to the discovery of several interesting new methods for generating the pentadienyl cation intermediate central to the cyclization. Methods reviewed include carbon-heteroatom ionization, functionalization of a double bond, nucleophilic addition, or electrocyclic ring opening. Additional variations employ unconventional substrates to produce novel pentacycles, such as the iso- and imino-Nazarov. Herein, we provide an overview of these unconventional, yet highly useful versions of the Nazarov cyclization.
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Affiliation(s)
- William T. Spencer
- Department of Chemistry, University of Rochester, RC Box 270216, Rochester, NY 14627
| | - Tulaza Vaidya
- Department of Chemistry and Chemical Biology, Cornell University Baker Laboratory Ithaca, NY 14853
| | - Alison J. Frontier
- Department of Chemistry, University of Rochester, RC Box 270216, Rochester, NY 14627
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Nunes JPM, Afonso CAM, Caddick S. Synthesis of 2,4-bifunctionalised cyclopentenones from 2-furaldehyde. RSC Adv 2013. [DOI: 10.1039/c3ra42663g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Daskhan GC, Jayaraman N. Synthesis of 2-Deoxy-2-C-alkyl Glycal and Glycopyranosides from 2-Hydroxy Glycal Ester. J Org Chem 2012; 77:2185-91. [DOI: 10.1021/jo202240f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gour Chand Daskhan
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India
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Filice M, Palomo JM. Monosaccharide derivatives as central scaffolds in the synthesis of glycosylated drugs. RSC Adv 2012. [DOI: 10.1039/c2ra00515h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Tian Q, Dong L, Ma X, Xu L, Hu C, Zou W, Shao H. Stereoselective Synthesis of 2-C-Branched (Acetylmethyl) Oligosaccharides and Glycoconjugates: Lewis Acid-Catalyzed Glycosylation from 1,2-Cyclopropaneacetylated Sugars. J Org Chem 2011; 76:1045-53. [DOI: 10.1021/jo1016579] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qiang Tian
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Liang Dong
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Xiaofeng Ma
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Liyan Xu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Changwei Hu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Wei Zou
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada, and Graduate School of Chinese Academy of Sciences, China
| | - Huawu Shao
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
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Wu AT, Yi T, Shao H, Wu SH, Zou W. Stereoselective synthesis of dioxabicycles from 1-C-allyl-2-O-benzyl-glycosides An intramolecular cyclization between 2-O-benzyl oxygen and the allyl double bond. CAN J CHEM 2006. [DOI: 10.1139/v06-046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Addition of a proton to the double bond of 1-C-allyl-O-benzylglycosides gave a 2′-carbonium ion, which in turn reacted intramolecularly, in a regio- and diastereo-selective manner, with the nucleophilic oxygen of the 2-O-benzyl group to form an oxonium intermediate. Subsequent cleavage of the benzyl CO bond led to dioxabicycles in moderate yields. Surprisingly, opposite diastereoselectivities were observed from 1-C-allylglycofuranosides and 1-C-allylglycopyranosides, which produced 2,2′-trans- and 2,2′-cis-dioxabicycles, respectively.Key words: C-glycoside, olefin, cyclization, oxocarbonium, dioxabicycles.
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Yi T, Wu SH, Zou W. Synthesis of C-5-thioglycopyranosides and their sulfonium derivatives from 1-C-(2′-oxoalkyl)-5-S-acetylglycofuranosides. Carbohydr Res 2005; 340:235-44. [PMID: 15639243 DOI: 10.1016/j.carres.2004.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Accepted: 11/18/2004] [Indexed: 11/21/2022]
Abstract
1-C-(2'-oxoalkyl)-5-S-acetylglycofuranosides of L-arabinose, D-ribose, and D-xylose were converted to 1-C-(2'-oxoalkyl)-5-thioglycopyranosides by base treatment. The transformation was achieved through beta-elimination to an acyclic alpha,beta-conjugated aldehyde (ketone or ester), followed by an intramolecular hetero-Michael addition by the 5-thiol group. The cycloaddition was highly stereoselective in favor of an equatorial 1-C-substitution. The resultant C-5-thioglycopyranosides were further converted to the sulfonium salts by treatment with cyclic sulfate and methyl iodide. Two sulfonium isomers were obtained due to the presence of both S-axial and S-equatorial substitutions. We observed that the chemical shifts of both C-1 and C-5 in the S-axial substituted sulfonium sugars are always shifted up-field (5-10 ppm) in comparison to those in the S-equatorial substitutions (deltaC 49-53 ppm vs 42-45 ppm at C-1 and 37-42 ppm vs 32-35 ppm at C-5), which provides an easy way for determination of the stereochemistry.
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Affiliation(s)
- Tian Yi
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada
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Zou W, Shao H, Wu SH. Intramolecular aldol cyclization of C-4-ulopyranosyl-2'-oxoalkanes controlled by steric effects. Asymmetric synthesis of substituted 8-oxabicyclo[3.2.1]octanones and -octenones and cyclopentenones. Carbohydr Res 2004; 339:2475-85. [PMID: 15476708 DOI: 10.1016/j.carres.2004.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Accepted: 08/13/2004] [Indexed: 11/23/2022]
Abstract
Whereas C-2- and 4-ulopyranosyl compounds (C-2- and C-4-ulosides) can be converted to cyclopentenones under base conditions through beta-elimination and ring contraction, base-initiated beta-elimination of C-glycosyl 2'-aldehydes and 2'-ketones results in the formation of acyclic alpha,beta-unsaturated aldehydes or ketones. By combining both molecular features we synthesized 1-C-(4-ulopyranosyl)-2-oxoalkanes 6, 13, and 20 and investigated their reactions when they were treated with base. Both alpha- and beta-anomers of C-(4-ulopyranosyl)acetaldehydes 6 and 13 underwent a fast intramolecular aldol reaction between the C-5 enolate and 2'-aldehyde to form optically pure 8-oxabicyclo[3.2.1]octanones, which further transformed to 8-oxabicyclo[3.2.1]octenones 14 and 15 by beta-elimination. However, this aldol reaction did not occur when 1-C-(4-ulopyranosyl)propan-2-one 20 was treated with base because of steric hindrance exerted by the additional methyl group. Instead, an alternate C-3 enolization led to beta-elimination and further electro-ring opening to form an acyclic enol, which was then converted through a disrotatory intramolecular aldol cyclization to a cis-substituted cyclopentenone 21.
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Affiliation(s)
- Wei Zou
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.
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