51
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Zurek JM, Rae RL, Paterson MJ, Bebbington MWP. Unusual structure-energy correlations in intramolecular Diels-Alder reaction transition states. Molecules 2014; 19:15535-45. [PMID: 25268713 PMCID: PMC6272020 DOI: 10.3390/molecules191015535] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/01/2014] [Accepted: 09/16/2014] [Indexed: 11/17/2022] Open
Abstract
Detailed analysis of calculated data from an experimental/computational study of intramolecular furan Diels-Alder reactions has led to the unusual discovery that the mean contraction of the newly forming C-C σ-bonds from the transition state to the product shows a linear correlation with both reaction Gibbs free energies and reverse energy barriers. There is evidence for a similar correlation in other intramolecular Diels-Alder reactions involving non-aromatic dienes. No such correlation is found for intermolecular Diels-Alder reactions.
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Affiliation(s)
- Justyna M Zurek
- Institute of Chemical Science, School of Engineering and Physical Sciences, William Perkin building, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Robert L Rae
- Institute of Chemical Science, School of Engineering and Physical Sciences, William Perkin building, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Martin J Paterson
- Institute of Chemical Science, School of Engineering and Physical Sciences, William Perkin building, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - Magnus W P Bebbington
- Institute of Chemical Science, School of Engineering and Physical Sciences, William Perkin building, Heriot-Watt University, Edinburgh EH14 4AS, UK.
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52
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Halogen effect on tandem [4+2] cycloaddition/aromatization sequence of allenyl 2-halo-3-vinylcyclohex-2-enyl ether. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.05.074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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53
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Pham HV, Paton R, Ross AG, Danishefsky SJ, Houk KN. Intramolecular Diels-Alder reactions of cycloalkenones: stereoselectivity, Lewis acid acceleration, and halogen substituent effects. J Am Chem Soc 2014; 136:2397-403. [PMID: 24410341 PMCID: PMC3965351 DOI: 10.1021/ja410220w] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 11/29/2022]
Abstract
The intramolecular Diels-Alder reactions of cycloalkenones and terminal dienes occur with high endo stereoselectivity, both thermally and under Lewis-acidic conditions. Through computations, we show that steric repulsion and tether conformation govern the selectivity of the reaction, and incorporation of either BF3 or α-halogenation increases the rate of cycloaddition. With a longer tether, isomerization from a terminal diene to the more stable internal diene results in a more facile cycloaddition.
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Affiliation(s)
- Hung V. Pham
- Department
of Chemistry and Biochemistry, University
of California-Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Robert
S. Paton
- Department
of Chemistry and Biochemistry, University
of California-Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Audrey G. Ross
- Department
of Chemistry, Columbia University, Havemeyer Hall, 3000 Broadway, New York, New York 10027, United States
- Novartis
Institutes for BioMedical Research, Inc., 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Samuel J. Danishefsky
- Department
of Chemistry, Columbia University, Havemeyer Hall, 3000 Broadway, New York, New York 10027, United States
- Laboratory
for Bioorganic Chemistry, Sloan-Kettering
Institute for Cancer Research, 1275 York Avenue, New York, New York 10065, United
States
| | - K. N. Houk
- Department
of Chemistry and Biochemistry, University
of California-Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
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54
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Rae RL, Żurek JM, Paterson MJ, Bebbington MWP. Halogenation effects in intramolecular furan Diels-Alder reactions: broad scope synthetic and computational studies. Org Biomol Chem 2013; 11:7946-52. [PMID: 24135947 DOI: 10.1039/c3ob41616j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the first time a comprehensive synthetic and computational study of the effect of halogen substitution on both furan and dienophile for the intramolecular Furan Diels-Alder (IMDAF) reaction has been undertaken. Contrary to our initial expectations, halogen substitution on the dienophile was found to have a significant effect, making the reactions slower and less thermodynamically favourable. However, careful choice of the site of furan halogenation could be used to overcome dienophile halogen substitution, leading to highly functionalised cycloadducts. These reactions are thought to be controlled by the interplay of three factors: positive charge stabilisation in the transition state and product, steric effects and a dipolar interaction term identified by high level calculations. Frontier orbital effects do not appear to make a major contribution in determining the viability of these reactions, which is consistent with our analysis of calculated transition state structural data.
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Affiliation(s)
- Robert L Rae
- Institute of Chemical Science, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK.
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55
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Yoshida N, Tanaka H, Hirata F. Theoretical Study of Salt Effects on the Diels–Alder Reaction of Cyclopentadiene with Methyl Vinyl Ketone Using RISM-SCF Theory. J Phys Chem B 2013; 117:14115-21. [PMID: 24144235 DOI: 10.1021/jp4091552] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Norio Yoshida
- Department
of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1
Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Hidetsugu Tanaka
- Advancing Analysis
Laboratory, Mitsui Chemicals, Inc., 580-32 Nagaura, Sodegaura Chiba 299-0265, Japan
| | - Fumio Hirata
- College of
Life
Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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56
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Lu L, Hu H, Hou H, Wang B. An improved B3LYP method in the calculation of organic thermochemistry and reactivity. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.04.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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57
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Chmely SC, Kim S, Ciesielski PN, Jiménez-Osés G, Paton RS, Beckham GT. Mechanistic Study of a Ru-Xantphos Catalyst for Tandem Alcohol Dehydrogenation and Reductive Aryl-Ether Cleavage. ACS Catal 2013. [DOI: 10.1021/cs400110r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
| | | | | | - Gonzalo Jiménez-Osés
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive,
Los Angeles, California 90095-1569, United States
| | - Robert S. Paton
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
| | - Gregg T. Beckham
- Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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58
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Nieto-García O, Alonso R. IMDAF/aromatization path of halogenated furylacrylamides and furylpropiolamides to dihydroisoquinolin-1(2H)-ones. J Org Chem 2013; 78:2564-70. [PMID: 23379831 DOI: 10.1021/jo302750s] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intramolecular Diels-Alder cycloadditions of chlorofuryl- (R = Cl) secondary (R' = H) acrylamides and propiolamides of type 1 followed by (optional modification and) base-induced aromatization of the resulting chlorinated oxanorborn(adi)enes 2 afford N-free-dihydroisoquinolin-1(2H)-ones 3 with different aromatic substitution patterns.
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Affiliation(s)
- Olaia Nieto-García
- Department of Organic Chemistry, University of Santiago de Compostela, Campus Vida sn, 15782 Santiago de Compostela, A Coruña, Spain
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59
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Caillot G, Hegde S, Gras E. A mild entry to isoindolinones from furfural as renewable resource. NEW J CHEM 2013. [DOI: 10.1039/c3nj41050a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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60
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Nieto-García O, Alonso R. Synthesis and cytotoxicity of (+/−)-7,9-dideoxy-pancratistatin analogues. Org Biomol Chem 2013. [DOI: 10.1039/c2ob27127c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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61
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Chéron N, Jacquemin D, Fleurat-Lessard P. A qualitative failure of B3LYP for textbook organic reactions. Phys Chem Chem Phys 2012; 14:7170-5. [DOI: 10.1039/c2cp40438a] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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62
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Boutelle RC, Northrop BH. Substituent effects on the reversibility of furan-maleimide cycloadditions. J Org Chem 2011; 76:7994-8002. [PMID: 21866976 DOI: 10.1021/jo201606z] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effects of furan and maleimide substitution on the dynamic reversibility of their Diels-Alder reactivity have been investigated computationally and by (1)H NMR spectroscopy. Furan and furan derivatives bearing methoxy, methyl, or formyl groups at their 2- or 3-positions were investigated with maleimide and maleimide derivatives bearing N-methyl, N-allyl, and N-phenyl substituents. Computational predictions indicate that electronic and regiochemical effects of furan substitution significantly influence their Diels-Alder reactivity with maleimide, with reaction free energies of exo adduct formation ranging from ΔG = -9.4 to 0.9 kcal/mol and transition state barriers to exo adduct formation ranging from ΔG(‡) = 18.9 to 25.6 kcal/mol. Much less variation was observed for the reactivity of N-substituted maleimide derivatives and furan, with reaction and transition state free energies each falling within a range of 1.1 kcal/mol. Dynamic exchange experiments monitored by (1)H NMR spectroscopy support computational predictions. The results indicate the reactivity and reversibility of furan-maleimide cycloadditions can be tuned significantly through the addition of appropriate substituents and have implications in the use of furan and maleimide derivatives in the construction of thermally responsive organic materials.
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Affiliation(s)
- Robert C Boutelle
- Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459, United States
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63
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Paton RS, Kim S, Ross AG, Danishefsky SJ, Houk KN. Experimental Diels-Alder Reactivities of Cycloalkenones and Cyclic Dienes Explained through Transition-State Distortion Energies. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201103998] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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64
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Paton RS, Kim S, Ross AG, Danishefsky SJ, Houk KN. Experimental Diels-Alder Reactivities of Cycloalkenones and Cyclic Dienes Explained through Transition-State Distortion Energies. Angew Chem Int Ed Engl 2011; 50:10366-8. [DOI: 10.1002/anie.201103998] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Indexed: 11/07/2022]
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65
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Sarotti AM, Spanevello RA, Suárez AG. Assessing the halogen effect in Diels–Alder reactions involving chiral α-halo enones. A combined experimental and DFT computational approach. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.05.143] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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66
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Agopcan S, Çelebi-Ölçüm N, Üçışık MN, Sanyal A, Aviyente V. Origins of the diastereoselectivity in hydrogen bonding directed Diels–Alder reactions of chiral dienes with achiral dienophiles: a computational study. Org Biomol Chem 2011; 9:8079-88. [DOI: 10.1039/c1ob06285a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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67
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Photosensitized intramolecular cyclization of furan and non-activated alkene: pathway switching by the substituent on the furan ring. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2009.12.123] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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68
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Lam YH, Stanway SJ, Gouverneur V. Recent progress in the use of fluoroorganic compounds in pericyclic reactions. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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69
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Paddon-Row MN, Longshaw AI, Willis AC, Sherburn MS. On the effect of tether composition on cis/trans selectivity in intramolecular Diels-Alder reactions. Chem Asian J 2009; 4:126-34. [PMID: 19006172 DOI: 10.1002/asia.200800352] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Intramolecular Diels-Alder (IMDA) transition structures (TSs) and energies have been computed at the B3LYP/6-31+G(d) and CBS-QB3 levels of theory for a series of 1,3,8-nonatrienes, H(2)C=CH-CH=CH-CH(2)-X-Z-CH=CH(2) [-X-Z- = -CH(2)-CH(2)- (1); -O-C(=O)- (2); -CH(2)-C(=O)- (3); -O-CH(2)- (4); -NH-C(=O)- (5); -S-C(=O)- (6); -O-C(=S)- (7); -NH-C(=S)- (8); -S-C(=S)- (9)]. For each system studied (1-9), cis- and trans-TS isomers, corresponding, respectively, to endo- and exo-positioning of the -C-X-Z- tether with respect to the diene, have been located and their relative energies (E(rel) (TS)) employed to predict the cis/trans IMDA product ratio. Although the E(rel) (TS) values are modest (typically <3 kJ mol(-1)), they follow a clear and systematic trend. Specifically, as the electronegativity of the tether group X is reduced (X=O --> NH or S), the IMDA cis stereoselectivity diminishes. The predicted stereochemical reaction preferences are explained in terms of two opposing effects operating in the cis-TS, namely (1) unfavorable torsional (eclipsing) strain about the C4-C5 bond, that is caused by the -C-X-C(=Y)- group's strong tendency to maintain local planarity; and (2) attractive electrostatic and secondary orbital interactions between the endo-(thio)carbonyl group, C=Y, and the diene. The former interaction predominates when X is weakly electronegative (X=N, S), while the latter is dominant when X is more strongly electronegative (X=O), or a methylene group (X=CH(2)) which increases tether flexibility. These predictions hold up to experimental scrutiny, with synthetic IMDA reactions of 1, 2, 3, and 4 (published work) and 5, 6, and 8 (this work) delivering ratios close to those calculated. The reactions of thiolacrylate 5 and thioamide 8 represent the first examples of IMDA reactions with tethers of these types. Our results point to strategies for designing tethers, which lead to improved cis/trans-selectivities in IMDAs that are normally only weakly selective. Experimental verification of the validity of this claim comes in the form of fumaramide 14, which undergoes a more trans-selective IMDA reaction than the corresponding ester tethered precursor 13.
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Affiliation(s)
- Michael N Paddon-Row
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
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70
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Pieniazek SN, Clemente FR, Houk KN. Sources of error in DFT computations of C-C bond formation thermochemistries: pi-->sigma transformations and error cancellation by DFT methods. Angew Chem Int Ed Engl 2008; 47:7746-9. [PMID: 18752237 DOI: 10.1002/anie.200801843] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Susan N Pieniazek
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA
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71
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Ram RN, Kumar N. Synthesis of highly substituted m-chlorophenolic biaryls by chlorine substituent-promoted Diels–Alder reaction of 2-aryl-3-chlorofurans. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.07.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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72
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Pieniazek S, Clemente F, Houk K. Sources of Error in DFT Computations of CC Bond Formation Thermochemistries: π→σ Transformations and Error Cancellation by DFT Methods. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801843] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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73
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France S, Boonsombat J, Leverett CA, Padwa A. Cycloaddition across the benzofuran ring as an approach to the morphine alkaloids. J Org Chem 2008; 73:8120-3. [PMID: 18788783 DOI: 10.1021/jo8016956] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The intramolecular Diels-Alder reaction of several amidofurans tethered onto a benzofuran ring was examined as a strategy for the synthesis of morphine. Bromo substitution on the furan ring did not provide sufficient activation to allow the cycloaddition to take place across the aromatic benzofuran. However, the presence of a large o-methylbenzyl group on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be highly populated, thereby facilitating its Diels-Alder cycloaddition across a tethered benzofuran.
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Affiliation(s)
- Stefan France
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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74
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Claeys DD, Moonen K, Roman BI, Nemykin VN, Zhdankin VV, Waroquier M, Van Speybroeck V, Stevens CV. Synthesis of Tricyclic Phosphonopyrrolidines via IMDAF: Experimental and Theoretical Investigation of the Observed Stereoselectivity. J Org Chem 2008; 73:7921-7. [DOI: 10.1021/jo801138s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Diederica D. Claeys
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Kristof Moonen
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Bart I. Roman
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Victor N. Nemykin
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Viktor V. Zhdankin
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Michel Waroquier
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Veronique Van Speybroeck
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
| | - Christian V. Stevens
- Research Group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, and Center for Molecular Modeling, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium
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75
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Ram RN, Kumar N. Synthesis of 2,4-disubstituted 3-chlorofurans and the effect of the chlorine substituent in furan Diels–Alder reactions. Tetrahedron Lett 2008. [DOI: 10.1016/j.tetlet.2007.11.193] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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76
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Hou XL, Yang Z, Yeung KS, Wong HN. Chapter 5.3 Five-membered ring systems: furans and benzofurans. PROGRESS IN HETEROCYCLIC CHEMISTRY 2008. [DOI: 10.1016/s0959-6380(08)80009-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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77
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O'Hagan D. Understanding organofluorine chemistry. An introduction to the C-F bond. Chem Soc Rev 2007; 37:308-19. [PMID: 18197347 DOI: 10.1039/b711844a] [Citation(s) in RCA: 2593] [Impact Index Per Article: 152.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorine is the most electronegative element in the periodic table. When bound to carbon it forms the strongest bonds in organic chemistry and this makes fluorine substitution attractive for the development of pharmaceuticals and a wide range of speciality materials. Although highly polarised, the C-F bond gains stability from the resultant electrostatic attraction between the polarised C delta+ and F delta- atoms. This polarity suppresses lone pair donation from fluorine and in general fluorine is a weak coordinator. However, the C-F bond has interesting properties which can be understood either in terms of electrostatic/dipole interactions or by considering stereoelectronic interactions with neighbouring bonds or lone pairs. In this tutorial review these fundamental aspects of the C-F bond are explored to rationalise the geometry, conformation and reactivity of individual organofluorine compounds.
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Affiliation(s)
- David O'Hagan
- School of Chemistry and Centre for Biomolecular Science, University of St Andrews, North Haugh, St Andrews, UK KY16 9ST.
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78
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Amalin Kavitha A, Singha NK. A tailor-made polymethacrylate bearing a reactive diene in reversible diels-alder reaction. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22195] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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79
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Brubaker JD, Myers AG. A practical, enantioselective synthetic route to a key precursor to the tetracycline antibiotics. Org Lett 2007; 9:3523-5. [PMID: 17691796 PMCID: PMC3178443 DOI: 10.1021/ol071377d] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A practical, enantioselective synthetic route to a key precursor to the tetracycline antibiotics is reported. The route proceeds in nine steps (21% yield) from the commercial substance methyl 3-hydroxy-5-isoxazolecarboxylate. Key steps in the route involve enantioselective addition of divinylzinc to 3-benzyloxy-5-isoxazolecarboxaldehyde and an endo-selective intramolecular furan Diels-Alder cycloaddition reaction. The route described has provided more than 40 g of chromatographically pure 1 with 93% ee.
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Affiliation(s)
- Jason D. Brubaker
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Andrew G. Myers
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
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Acevedo O, Jorgensen WL. Understanding Rate Accelerations for Diels−Alder Reactions in Solution Using Enhanced QM/MM Methodology. J Chem Theory Comput 2007; 3:1412-9. [DOI: 10.1021/ct700078b] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Orlando Acevedo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, and Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-8107
| | - William L. Jorgensen
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, and Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-8107
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81
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Griffith GA, Hillier IH, Moralee AC, Percy JM, Roig R, Vincent MA. Interplay of Structure and Reactivity in a Most Unusual Furan Diels-Alder Reaction. J Am Chem Soc 2006; 128:13130-41. [PMID: 17017793 DOI: 10.1021/ja061458p] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Difluorinated alkenoate ethyl 3,3-difluoro-2-(N,N-diethylcarbamoyloxy)-2-propenoate reacts rapidly and in high yield with furan and a range of substituted furans in the presence of a tin(IV) catalyst. Non-fluorinated congener 2-(N,N-diethylcarbamoyloxy)-2-propenoate fails to react at all under the same conditions. These reactions have been explored using density functional theory (DFT) calculations. They reveal a highly polar transition state, which is stabilized by the Lewis acid catalyst SnCl(4) and by polar solvents. In the presence of both catalyst and solvent, a two-step reaction is predicted, corresponding to the stepwise formation of the two new carbon-carbon bonds via transition states which have similar energies in all cases. Our experimental observations of the lack of reaction of the non-fluorinated dienophile, the stereochemical outcomes, and the rate acceleration accompanying furan methylation are all well predicted by our calculations. The calculated free energy barriers generally correlate well with measured reaction rates, supporting a reaction mechanism in which zwitterionic character is developed strongly. An in situ ring opening reaction of exo-cycloadduct ethyl exo-2-(N,N-diethylcarbamoyloxy)-3,3-difluoro-7-oxabicyclo[2.2.1]hept-5-enyl-2-endo-carboxylate, which results in the formation of cyclic carbonate ethyl 4,4-difluoro-5-hydroxy-2-oxo-5,7a-dihydro-4H-benzo[1,3]dioxole-3a-carboxylate by a Curtin-Hammett mechanism, has also been examined. Substantial steric opposition to Lewis acid binding prevents carbonate formation from 2-substituted furans.
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Affiliation(s)
- Gerry A Griffith
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
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82
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Padwa A, Crawford KR, Straub CS, Pieniazek SN, Houk KN. Halo Substituent Effects on Intramolecular Cycloadditions Involving Furanyl Amides. J Org Chem 2006; 71:5432-9. [PMID: 16839120 DOI: 10.1021/jo0602322] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intramolecular Diels-Alder reactions involving a series of N-alkenyl-substituted furanyl amides were investigated. Stable functionalized oxanorbornenes were formed in high yield upon heating at 80-110 degrees C. The cycloaddition reactions include several bromo-substituted furanyl amides, and these systems were found to proceed at a much faster rate and in higher yield than without substitution. This effect was observed by incorporating a halogen in the 3- or 5-position of the furan ring and appears to be general. The origin of increased cycloaddition rates for halo-substituted furans has been investigated with quantum mechanical calculations. The success of these reactions is attributed to increases in reaction exothermicities; this both decreases activation enthalpies and increases barriers to retrocycloadditions. Halogen substitution on furan increases reactant energy and stabilizes the product, which is attributed to the preference of electronegative halogens to be attached to a more highly alkylated and therefore more electropositive framework.
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Affiliation(s)
- Albert Padwa
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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