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Chhetri BK, Lavoie S, Sweeney-Jones AM, Kubanek J. Recent trends in the structural revision of natural products. Nat Prod Rep 2019; 35:514-531. [PMID: 29623331 DOI: 10.1039/c8np00011e] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Covering: 2012 to 2017 This article reviews recent reports on the structural revision of natural products. Through a critical assessment of the original and revised published structures, the article addresses why each structure was targeted for revision, discusses the techniques and key discrepancies that led to the proposal of the revised structure, and offers measures that may have been taken during the original structure determination to prevent error. With the revised structures in hand, weaknesses of original proposals are assessed, providing a better understanding on the logic behind structure determination.
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Affiliation(s)
- Bhuwan Khatri Chhetri
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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2
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Chen X, Xiong F, Chen W, He Q, Chen F. Asymmetric Synthesis of the HMG-CoA Reductase Inhibitor Atorvastatin Calcium: An Organocatalytic Anhydride Desymmetrization and Cyanide-Free Side Chain Elongation Approach. J Org Chem 2014; 79:2723-8. [DOI: 10.1021/jo402829b] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Xiaofei Chen
- Department of Chemistry and ‡Institutes of Biomedical
Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Fangjun Xiong
- Department of Chemistry and ‡Institutes of Biomedical
Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Wenxue Chen
- Department of Chemistry and ‡Institutes of Biomedical
Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Qiuqin He
- Department of Chemistry and ‡Institutes of Biomedical
Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Fener Chen
- Department of Chemistry and ‡Institutes of Biomedical
Science, Fudan University, Shanghai 200433, People’s Republic of China
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Wu G, Sun X, Yu G, Wang W, Zhu T, Gu Q, Li D. Cladosins A-E, hybrid polyketides from a deep-sea-derived fungus, Cladosporium sphaerospermum. JOURNAL OF NATURAL PRODUCTS 2014; 77:270-5. [PMID: 24499327 DOI: 10.1021/np400833x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Five new fungal hybrid polyketides, cladosins A-D (1-4), that contain a novel linear 6(3)-enamino-8,10-dihydroxy-tetraketide (1 and 2) or 6-enamino-7(8)-en-10-ol (3 and 4) moiety, as well as the biogenetically related cladosin E (5), were isolated from the deep-sea-derived fungus Cladosporium sphaerospermum 2005-01-E3. Their structures (1-5) were elucidated through a combination of spectroscopic data, chemical conversion, and both Mosher's and Marfey's methods for stereochemical assignment. A plausible biogenetic pathway to 1-5 is proposed. Cladosin C (3) possesses mild anti-influenza A H1N1 virus activity.
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Affiliation(s)
- Guangwei Wu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China , Qingdao 266003, People's Republic of China
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Mousseau JJ, Morten CJ, Jamison TF. A dioxane template for highly selective epoxy alcohol cyclizations. Chemistry 2013; 19:10004-16. [PMID: 23775936 PMCID: PMC3763493 DOI: 10.1002/chem.201300845] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Indexed: 11/06/2022]
Abstract
Ladder polyether natural products are a class of natural products denoted by their high functional-group density and large number of well-defined stereocenters. They comprise the toxic component of harmful algal blooms (HABs), having significant negative economic and environmental ramifications. However, their mode of action, namely blocking various cellular ion channels, also denotes their promise as potential anticancer agents. Understanding their potential mode of biosynthesis will not only help with developing ways to limit the damage of HABs, but would also facilitate the synthesis of a range of analogs with interesting biological activity. 1,3-Dioxan-5-ol substrates display remarkable 'enhanced template effects' in water-promoted epoxide cyclization processes en route to the synthesis of these ladder polyether natural products. In many cases, they provide near complete endo-to-exo selectivity in the cyclization of epoxy alcohols, thereby strongly favoring the formation of tetrahydropyran (THP) over tetrahydrofuran (THF) rings. The effects of various Brønsted and Lewis acidic and basic conditions are explored to demonstrate the superior selectivity of the template over the previously reported THP-based epoxy alcohols. In addition, the consideration of other synthetic routes are also considered with the goal of gaining rapid access to a plethora of potential starting materials applicable towards the synthesis of ladder polyethers. Finally, cascade sequences with polyepoxides are investigated, further demonstrating the versatility of this new reaction template.
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Affiliation(s)
- James J. Mousseau
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
| | - Christopher J. Morten
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
| | - Timothy F. Jamison
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
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Kikuchi H, Sato Y, Kurata S, Katou Y, Oshima Y. Terresterol, a polyoxygenated lanostanoid, isolated from the oomycete Saprolegnia terrestris , and its innate immune-promoting activity. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.02.088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Molinski TF, Morinaka BI. INTEGRATED APPROACHES TO THE CONFIGURATIONAL ASSIGNMENT OF MARINE NATURAL PRODUCTS. Tetrahedron 2012; 68:9307-9343. [PMID: 23814320 PMCID: PMC3694619 DOI: 10.1016/j.tet.2011.12.070] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Tadeusz F. Molinski
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive MC0358, La Jolla, CA, 92093
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive MC0358, La Jolla, CA, 92093
| | - Brandon I. Morinaka
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive MC0358, La Jolla, CA, 92093
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Schönherr H, Mollitor J, Schneider C. A Chemoenzymatic Approach to the Stereocontrolled Synthesis of the C1-C11 fragment of (+)-Peloruside A. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000369] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Calvet G, Coote SC, Blanchard N, Kouklovsky C. α-Acyloxynitroso dienophiles in [4+2] hetero Diels–Alder cycloadditions: mechanistic insights. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.02.065] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Su Y, Xu Y, Han J, Zheng J, Qi J, Jiang T, Pan X, She X. Total synthesis of (-)-bitungolide F. J Org Chem 2009; 74:2743-9. [PMID: 19323573 DOI: 10.1021/jo9000146] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An efficient total synthesis of (-)-bitungolide F (6) in 17 steps and 20.1% yield is described herein. Key steps involve a Myers asymmetric alkylation to introduce the C6 methyl with proper stereochemistry, a Claisen-like cyclization to construct the alpha,beta-unsaturated delta-lactone and a Julia-Kocienski olefination to assemble the conjugated diene moiety.
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Affiliation(s)
- Yingpeng Su
- Department of Chemistry, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China
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Keck GE, Giles RL, Cee VJ, Wager CA, Yu T, Kraft MB. Total synthesis of epothilones B and D: stannane equivalents for beta-keto ester dianions. J Org Chem 2008; 73:9675-91. [PMID: 18991385 PMCID: PMC2736362 DOI: 10.1021/jo802215v] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies leading to a total synthesis of epothilones B and D are described. The overall synthetic plan was based on late-stage fragment assembly of two segments representing C(1)-C(9) and C(10)-C(21) of the structure. The C(1)-C(9) fragment was prepared by elaboration of commercially available (2R)-3-hydroxy-2-methylpropanoate at both ends of the three-carbon unit. Introduction of carbons 1-4 containing the gem-dimethyl unit was achieved in a convergent manner using a diastereoselective addition of a stannane equivalent of a beta-keto ester dianion. An enantioselective addition of such a stannane equivalent for a beta-keto ester dianion was also used to fashion one version of the C(10)-C(21) subunit; however, the fragment assembly (using bimolecular esterification followed by ring-closing metathesis) with this subunit failed. Therefore, fragment assembly was achieved using a Wittig reaction; this was followed by macrolactonization to close the macrocycle. The C(10)-C(21) subunit needed for this approach was prepared in an efficient manner using the Corey-Kim reaction as a key element. Other key reactions in the synthesis include a stereoselective SmI(2) reduction of a beta-hydroxy ketone and a critical opening of a valerolactone with aniline which required extensive investigation.
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Affiliation(s)
- Gary E Keck
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah, 84112, USA.
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12
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Nori-Shargh D, Rafatpanah S. Stereoelectronic Effects on the Conformational Properties of 1,3-Dioxane, 1,3-Dithiane, and 1,3-Diselenane: An Ab Initio Study and NBO Analysis. PHOSPHORUS SULFUR 2008. [DOI: 10.1080/10426500801963780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Davood Nori-Shargh
- a Chemistry Department, Graduate Faculty, Arak Branch , Islamic Azad University , Arak, Iran
- b Chemistry Department, Science and Research Campus , Islamic Azad University , Hesarak, Poonak, Tehran, Iran
| | - Shamsi Rafatpanah
- a Chemistry Department, Graduate Faculty, Arak Branch , Islamic Azad University , Arak, Iran
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Tormena CF, Dias LC, Rittner R. Orbital Interactions and Their Effects on 13C NMR Chemical Shifts for 4,6-Disubstituted-2,2-dimethyl-1,3-dioxanes. A Theoretical Study. J Phys Chem A 2005; 109:6077-82. [PMID: 16833944 DOI: 10.1021/jp052048a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A theoretical study is employed to describe the orbital interactions involved in the conformers' stability, the energies for the stereoelectronic interactions, and the corresponding effects of these interactions on the molecular structure (bond lengths) for cis- and trans-4,6-disubstituted-2,2-dimethyl-1,3-dioxanes. For cis-4,6-disubstituted-2,2-dimethyl-1,3-dioxanes, two LPO --> sigma*C(2)-Me(8) interactions are extremely important and the energies involved in these interactions are in the range 6.81-7.58 kcal mol(-1) for the LP(O)(1) --> sigma*C(2)-Me(8) and 7.58-7.71 kcal mol(-1) for the LP(O)(3) --> sigma*C(2)-Me(8) interaction. These two LP(O) --> sigma*C(2)-Me(8) interactions cause an upfield shift, indicating an increased shielding (increased electron density) of the ketal carbon C(2) as well as the axial Me(8) group in the chair conformation. These LP(O) --> sigma*C(2)-Me(8) hyperconjugative anomeric type interactions can explain the 13C NMR chemical shifts at 19 ppm for the axial methyl group "Me(8)" and 98.5 ppm for the ketal carbon "C(2)". The observed results for the trans derivatives showed that for compounds 2a-c (R = -CN, -C[triple bond]CH, and -CHO, respectively) the chair conformation is predominant, whereas for 2d,f-h [-CH3, -Ph, -C6H4(p-NO2), -C6H4(p-OCH3), respectively] the twist-boat is the most stable compound and for 2e [-C(CH3)3] is the only form.
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Affiliation(s)
- Claudio F Tormena
- Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto SP, Brazil.
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Davis TA, Chopade PR, Hilmersson G, Flowers RA. Reduction of β-Hydroxyketones by SmI2/H2O/Et3N. Org Lett 2004; 7:119-22. [PMID: 15624992 DOI: 10.1021/ol047835p] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reduction of a series of beta-hydroxyketones by SmI2/H2O/Et3N provided 1,3-diols in quantitative yields. The reactions were exceedingly clean with no byproduct formation, negating the need for further purification. Most reactions provided moderate to excellent diastereoselectivity with syn-diols as the major isomer in most instances.
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Affiliation(s)
- Todd A Davis
- Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
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15
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Formal total synthesis of altohyrtin C (spongistatin 2). Part 1: Aldol approach to unite AB and CD spiroacetals. Tetrahedron Lett 2003. [DOI: 10.1016/j.tetlet.2003.08.082] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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16
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Lii JH, Chen KH, Durkin KA, Allinger NL. Alcohols, ethers, carbohydrates, and related compounds. II. The anomeric effect. J Comput Chem 2003; 24:1473-89. [PMID: 12868111 DOI: 10.1002/jcc.10269] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The anomeric effect has been studied for a variety of compounds using the MM4 force field, and also using MP2/6-311++G(2d,2p) ab initio calculations and experimental data for reference purposes. Geometries and energies, including conformational, rotational barriers, and heats of formation were examined. Overall, the agreement of MM4 with the experimental and ab initio data is good, and significantly better than the agreement obtained with the MM3 force field. The anomeric effect is represented in MM4 by various explicit terms in the force constant matrix. The bond length changes are accounted for with torsion-stretch elements. The angle changes are accounted for with torsion-bend elements. The energies are taken into account with a number of torsional terms in the usual way. A torsion-torsion interaction is also of some importance. With all of these elements included in the calculation, the MM4 results now appear to be adequately accurate. The heats of formation were examined for a total of 12 anomeric compounds, and the experimental values were fit by MM4 with an RMS error of 0.42 kcal/mol.
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Affiliation(s)
- Jenn-Huei Lii
- Department of Chemistry, Computational Center for Molecular Structure and Design, Chemistry Annex, University of Georgia, Athens, Georgia 30602-2526, USA
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17
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Freeman F, Le KT. A Computational Study of Conformations and Conformers of 1,3-Dithiane (1,3-Dithiacyclohexane). J Phys Chem A 2003. [DOI: 10.1021/jp0138633] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fillmore Freeman
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025
| | - Kelly Thuy Le
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025
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Terauchi T, Terauchi T, Sato I, Tsukada T, Kanoh N, Nakata M. Synthetic studies on altohyrtins (spongistatins): synthesis of the C15–C28 (CD) spiroacetal portion. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(00)00237-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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20
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Wang J, Cieplak P, Kollman PA. How well does a restrained electrostatic potential (RESP) model perform in calculating conformational energies of organic and biological molecules? J Comput Chem 2000. [DOI: 10.1002/1096-987x(200009)21:12%3c1049::aid-jcc3%3e3.0.co;2-f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Wang J, Cieplak P, Kollman PA. How well does a restrained electrostatic potential (RESP) model perform in calculating conformational energies of organic and biological molecules? J Comput Chem 2000. [DOI: 10.1002/1096-987x(200009)21:12%3c1049::aid-jcc3%3e3.0.co%3b2-f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Wang J, Cieplak P, Kollman PA. How well does a restrained electrostatic potential (RESP) model perform in calculating conformational energies of organic and biological molecules? J Comput Chem 2000. [DOI: 10.1002/1096-987x(200009)21:12<1049::aid-jcc3>3.0.co;2-f] [Citation(s) in RCA: 3270] [Impact Index Per Article: 136.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ide M, Tsunashima K, Nakata M. Practical Synthesis of Four Stereoisomers of 6-(t-Butyldiphenylsiloxy)-3,5-dimethyl-1-(triphenylmethoxy)hexane-2,4-diol via Dithiane Coupling with Oxirane. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1999. [DOI: 10.1246/bcsj.72.2501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Nevins N, Cicero D, Snyder JP. A Test of the Single-Conformation Hypothesis in the Analysis of NMR Data for Small Polar Molecules: A Force Field Comparison. J Org Chem 1999. [DOI: 10.1021/jo9824450] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Neysa Nevins
- Department of Chemistry, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, and Istituto di Richerche di Biologia Molecolare P. Angeletti, 00040 Pomezia, Italy
| | - Daniel Cicero
- Department of Chemistry, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, and Istituto di Richerche di Biologia Molecolare P. Angeletti, 00040 Pomezia, Italy
| | - James P. Snyder
- Department of Chemistry, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, and Istituto di Richerche di Biologia Molecolare P. Angeletti, 00040 Pomezia, Italy
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Keck GE, Wager CA, Sell T, Wager TT. An Especially Convenient Stereoselective Reduction of β-Hydroxy Ketones to Anti 1,3 Diols Using Samarium Diiodide. J Org Chem 1999. [DOI: 10.1021/jo982428a] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gary E. Keck
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Carrie A. Wager
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Thorsten Sell
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Travis T. Wager
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
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Sarraf ST, Leighton JL. Unusual conformational effects on the regioselectivity of olefin insertion in the rhodium-catalyzed hydroformylation of 4-methylene-1,3-dioxanes. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)01351-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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29
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Freeman F, Lee C, Hehre WJ, Po HN. Ab initio molecular orbital calculations of 3,4-dihydro-1,2-dioxin, 3,6-dihydro-1,2-dioxin, 4H-1,3-dioxin (1,3-diox-4-ene), and 2,3-dihydro-1,4-dioxin (1,4-dioxene). J Comput Chem 1997. [DOI: 10.1002/(sici)1096-987x(199708)18:11<1392::aid-jcc6>3.0.co;2-g] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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Paquette LA, Kinney MJ, Dullweber U. Practical Synthesis of Spirocyclic Bis-C,C-glycosides. Mechanistic Models in Explanation of Rearrangement Stereoselectivity and the Bifurcation of Reaction Pathways. J Org Chem 1997. [DOI: 10.1021/jo962020i] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Leo A. Paquette
- Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210
| | - Margaret J. Kinney
- Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210
| | - Uta Dullweber
- Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210
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Conformational Analysis of Saturated Six-Membered Oxygen-Containing Heterocyclic Rings. ADVANCES IN HETEROCYCLIC CHEMISTRY 1997. [DOI: 10.1016/s0065-2725(08)60083-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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32
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Paquette LA, Tae J. Stereocontrolled Preparation of Spirocyclic Ethers by Intramolecular Trapping of Oxonium Ions with Allylsilanes. J Org Chem 1996; 61:7860-7866. [PMID: 11667744 DOI: 10.1021/jo961306k] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The stereoselectivity of the spontaneous intramolecular cyclization of 2-(benzenesulfonyl)-2-(4-((trimethylsilyl)methyl)-4-pentenyl)tetrahydropyrans substituted by alkyl groups at various ring positions has been examined. For the 4- and 6-methyl derivatives, formation of the spirocyclic center occurs exclusively anti to the methyl. The outcome in the 5-methyl example is a 3.7:1 syn/anti split. For the trans-4,6-dimethyl derivative, the substituents act in a reinforcing manner and direct cyclization uniquely in one direction. Both the cis and trans bicyclic ethers ring close on that pi-surface of the intermediate oxonium ion syn to the angular hydrogen. The results are rationalized in terms of the predilection of the associated oxonium ions for nucleophilic capture via a chairlike or twist-boat transition state.
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Affiliation(s)
- Leo A. Paquette
- Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210
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33
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Kollman PA. Advances and Continuing Challenges in Achieving Realistic and Predictive Simulations of the Properties of Organic and Biological Molecules. Acc Chem Res 1996. [DOI: 10.1021/ar9500675] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peter A. Kollman
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California,
San Francisco, California 94143-0446
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34
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Bakowies D, Thiel W. Hybrid Models for Combined Quantum Mechanical and Molecular Mechanical Approaches. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp9536514] [Citation(s) in RCA: 999] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dirk Bakowies
- Organisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Walter Thiel
- Organisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Rychnovsky SD, Richardson TT. Relative und absolute Konfiguration von Filipin III. Angew Chem Int Ed Engl 1995. [DOI: 10.1002/ange.19951071125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
When energy is a critical quantity, accurate biomolecular simulations rest in substantial part on accurate potential energy functions (force fields). Improvements in methodology for determining parameters--particularly, in the systematic use of computational data obtained from quantum chemical calculations--and enhancements in functional form are leading to better potential energy functions. New calculations have been developed for water (including calculations that incorporate electronic polarizability to take account of the degree to which a molecule can be polarized), proteins, nucleic acids, carbohydrates, lipids, and general organic molecules. Most notably, two new biomolecular force fields have recently been derived and significant redeterminations of the parameters of two existing biomolecular force fields have been carried out. Some progress has also been made in incorporating polarizability into potential energy functions for molecules in general and in improving the treatment of metal-ligand interactions in systems of biomolecular interest.
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Enantioselective synthesis of bis(γ-butyrolactones). Their oxidative degradation to tetraols as a key step in stereoselective syntheses of 1,3,5,7,9-pentaol synthons for polyhydroxylated natural products. ACTA ACUST UNITED AC 1995. [DOI: 10.1002/jlac.199519950246] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Howard AE, Cieplak P, Kollman PA. A molecular mechanical model that reproduces the relative energies for chair and twist-boat conformations of 1,3-dioxanes. J Comput Chem 1995. [DOI: 10.1002/jcc.540160211] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Spectroscopic, crystallographic and computational studies of the formation and isomerization of cyclic acetals and ketals of pentonolactones. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s0957-4166(00)80400-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Costanzo MJ, Almond HR, Gauthier A, Maryanoff BE. Non-chair six-membered-ring conformations. Preference for a twist-boat (or skew) structure in α-L-sorbopyranose derivatives. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s0957-4166(00)80393-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Nakata M, Tamai T, Kamio T, Kinoshita M, Tatsuta K. The Total Synthesis of AB3217-A, a Novel Anti-mite Substance, via Intermolecular Etherification and Intramolecular Glycosylation. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1994. [DOI: 10.1246/bcsj.67.3057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Diastereospecific synthesis of 2′- or 3′-c-branched nucleosides through intramolecular free-radical capture by silicon-tethered acetylene. Tetrahedron 1994. [DOI: 10.1016/s0040-4020(01)90435-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Domínguez E, Carretero JC. Flexible and stereoselective construction of polypropionate chains from enantiomerically pure γ-hydroxy-α,β-unsaturated sulfones. Tetrahedron 1994. [DOI: 10.1016/s0040-4020(01)90483-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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