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CHEM 635 Joseph M. Fox Spring 2014 Tuesdays, 7-10 Pm, Brown CHEM 635 Joseph M. Fox Spring 2014 Tuesdays, 7-10 pm, Brown lab 207 212 LDL (office), 302-831-0191 [email protected] Syllabus for CHEM 635-revised Spring 2014 Tuesdays, 7-10 pm, Brown lab 207 Joseph M. Fox, 212 LDL (office), 302-831-0191 [email protected] Blemings, Andrew Demeester, Kristen Papers will be posted on a week-by-week basis. Kenny, Douglas Students should post their presentations (as pdf files, ppt, or keynote files) Peng, Yiyun the day before lecture. Roberts, Daniel Week 1 Feb 11: Introductory lecture. Lecture notes will be posted. Week 2 Feb 18: introduction to photochemistry Week 3 Feb 25: Student Presentations Week 4 Mar 4: special topics Week 5 Mar 11: Exam 1 Week 6 Mar 18: special topics Week 7 Mar 25: Student Presentations Apr 1: SPRING BREAK Week 8 Apr 8: special topics Grading Presentations: 20% Week 9 Apr 15: Synthesis Week Exams: 60% total Week 10 Apr 22: workshop Synthesis Week 20% Week 11 Apr 29: Exam 2 Week 12 May 6: Student Presentations Presentations Week 13 May 13: special topics A successful presentation should contain the following elements: • Discuss context (importance, history, note other syntheses) • discuss scientists involved Exam 3 TBA • show 3-D structure; use 3-D in your analysis • retrosynthesis OFFICE HOURS: Fridays 10-11, or by appointment • forward synthesis • know the mechanisms in the paper • your presentation should last for 15 minutes, with 15 minutes of Q&A Blemings, Andrew tridachiahydropyrone (electrocyclization) a) P. Sharma, N. Griffiths, J. E. Moses, Org. Lett. 2008, 10, 4025 – 4027; (full paper: P. Sharma, J. E. Moses, Synlett 2010, 525 – 528.) Demeester, Kristen mannostatin (electrocyclization): R. Ling, P. S. Mariano, J. Org. Chem. 1998, 63, 6072 – 6076. Kenny, Douglas cedrol (di-pi-methane): a) K. E. Stevens, P. Yates, J. Chem. Soc. Chem. Commun. 1980, 990 – 991 (full paper: P. Yates, K. E. Stevens, Tetrahedron 1981, 37, 4401 – 4410._ Peng, Yiyun longifolene (De Mayo Reaction) W. Oppolzer, T. Godel, J. Am. Chem. Soc. 1978, 100, 2583 – 2584; Roberts, Daniel cedrane (meta photocycloaddition) P. A. Wender, J. J. Howbert, J. Am. Chem. Soc. 1981, 103, 688 – 690. estrone (Photodienol) : G. Quinkert, W.-D. Weber, U. Schwartz, G. Dürner, Angew. Chem. Int. Ed. Engl. 1980, 19, 1027–1029. Enantioselective: Angew. Chem. Int. Ed. Engl. 1980, 19, 1029 – 1030 isocomene (Paterno Buchi reaction): V. H. Rawal, C. Dufour, J. Am. Chem. Soc. 1994, 116, 2613 –2614. modhephene (meta photocycloaddition) P.A.Wender,G.B.Dreyer,J.Am.Chem.Soc.1982,104,5805– 5807. keys to the class mechanisms: see it, know it name reactions: hear it, know it 33% of exams from handouts; rest mechanisms Chem 635 Week 1 potential exam 1 questions Describe Julian's synthesis of eserethole Me Me EtO EtO N O Me N N H Me Me Describe Woodward's synthesis of rings I-III & V of strychnine Ts N O NH OMe CO2Et N 2 H N CO Me OMe 2 O Describe Woodward and Doering's synthesis of homomeroquinene AcN OH HN HO O Wöhler synthesis of urea Wöhler, 1928 – – + + NH Cl + K N C O 4 NH4 N C O O H2N NH2 Friedrich Wöhler Annalen der Physik und Chemie 1828, 88, 253–256 Significance: Wöhler was the first to make an organic substance from an inorganic substance. This was the beginning of the end of the theory of vitalism: the idea that organic and inorganic materials differed essentially by the presence of the “vital force”– present only in organic material. To his mentor Berzelius:“I can make urea without thereby needing to have kidneys, or anyhow, an animal, be it human or dog" Friedrich Wöhler, 1880-1882 Polytechnic School in Berlin Support for vitalism remained until 1845, when Kolbe synthesized acetic acid Polytechnic School at Kassel from carbon disulfide University of Göttingen Fischer synthesis of glucose PhHN N O N O NHPh Br aq. HCl Δ PhNH2NH2 HO H HO H O Br "α−acrose" H OH H OH H OH H OH CH2OH CH2OH α−acrosazone α−acrosone an “osazone” (osazone test for Zn/AcOH reducing sugars) OH OH CO2H CHO O HO H HO H OH Br2 HO H HO H Na-Hg HO H HNO3 HO H H OH H OH H OH H OH then resolve H O+ H OH via strychnine H OH H OH 3 H OH CH2OH salts CH2OH CH OH CH2OH 2 D-Mannonic acid DL-Mannose DL-Mannitol DL-Fructose quinoline • Established stereochemical relationship CO2H CHO H OH H OH between mannose and glucose Na-Hg HO H HO H (part of Fischer proof) H OH + H OH H3O • work mechanisms from acrosazone on H OH H OH Emil Fischer, 1852-1919 CH2OH CH2OH University of Munich (1875-81) D-Gluconic acid D-Glucose University of Erlangen (1881-88) University of Würzburg (1888-92) University of Berlin (1892-1919) Fischer, E. Ber. 1890, 23, 799. also see: The total synthesis of natural products, Volume 1 By John ApSimon Terpenes Terpenes are derived biosynthetically from units of isoprene, which has the molecular formula C5H8. The basic molecular formulae of terpenes are multiples of that, (C5H8)n where n is the number of linked isoprene units. activated forms, isopentenyl pyrophosphate (IPP or also isopentenyl diphosphate) and dimethylallyl pyrophosphate (DMAPP or also dimethylallyl diphosphate), are the components in the biosynthetic pathway from wikipedia Terpenes ■ Monoterpenes consist of two isoprene units and have the molecular formula C10H16. Examples of monoterpenes are: geraniol, limonene and terpineol. ■ Sesquiterpenes consist of three isoprene units and have the molecular formula C15H24. Examples of sesquiterpenes are: farnesenes, farnesol. (The sesqui- prefix means one and a half.) ■ Diterpenes are composed for four isoprene units and have the molecular formula C20H32. They derive from geranylgeranyl pyrophosphate. Examples of diterpenes are cafestol, kahweol, cembrene and taxadiene (precursor of taxol). Diterpenes also form the basis for biologically important compounds such as retinol, retinal, and phytol. They are known to be antimicrobial and antiinflammatory. ■ Triterpenes consist of six isoprene units and have the molecular formula C30H48. The linear triterpene squalene, the major constituent of shark liver oil, is derived from the reductive coupling of two molecules of farnesyl pyrophosphate. Squalene is then processed biosynthetically to generate either lanosterol or cycloartenol, the structural precursors to all the steroids. farnesyl pyrophosphate ■ Tetraterpenes contain eight isoprene units and have the molecular formula C40H64. Biologically important tetraterpenes include the acyclic lycopene, the monocyclic gamma-carotene, and the bicyclic alpha- and beta-carotenes. ■ Polyterpenes consist of long chains of many isoprene units. Natural rubber consists of polyisoprene in which the double bonds are cis. Some plants produce a polyisoprene with trans double bonds, known as gutta-percha. http://en.wikipedia.org/wiki/Terpene Perkin Synthesis of a-terpineol and limonene O HO C ONa O CN aq. HCl 2 O CN O O I EtO2C CO2Et HO2C CO2H Ac2O heat CO Et CO H William Henry Perkin CO2H CO2H 2 2 1) MeMgI EtOH J. Chem. Soc., Trans., fuming HBr H+ 1904, 85, 654-671 2) aq. HCl Me Br Me OH O O Me OH CO2H CO2Et Me EtOH MeMgI KHSO4 H+ Me Me Me Me α-terpineol limonene Note: use of symmetry Sir William Henry Perkin vs 1838-1907 began study at age of 15 under August Wilhelm von Hofmann at Royal College of Chemistry in London (attempted study on synthesis of quinine) made mauveine at age 18 over easter break launched the synthetic dye industry (never mind quinine. .) Tropinone Me Me N Me N N atropine COOCH3 anticholinergic drug O used for Ph opthamology, O O O O recuscitation, cocaine tropinone HO organophosphate Ph poisoning Tropane alkaloids occur in plants of the families Erythroxylaceae (including coca) and Solanaceae from Wikipedia Tropinone First synthesis by Willstätter in 1901: arduous, 0.75% yield Robert Robinson, 1917: classic retrosynthetic analysis and biomimetic synthesis . and biomimetic synthesis 1886-1975 Institutions University of Sydney University of Liverpool British Dyestuffs Corporation University of Manchester University College, London University of Oxford Alma mater University of Manchester Birch, Arthur J., 'Investigating a Scientific Legend: the Tropinone Synthesis of Sir Robert Robinson, FRS', Notes and Records of the Royal Society of London, vol. 47, 1993, pp. 277-296 Tropinone Total synthesis Ca++ Me - N CO2 Me CHO N HCl •HCl CO2H NH2Me O CHO -CO CO - 2 2 HO2C O O Robinson J. Chem. Soc. 1917, 762. Mechanism: Double Mannich (go through entire mechanism yourself) OH CO2H OH CO2H CO2H CO2H + N OH N O N+ OH N O CO2H CO2H CO2H CO2H physostigmine African Calabar Bean • Potent reversible inhibitor of acetyl and butylcholinesterases • Clinical treatment of glaucoma (reduces intraocular pressure) • Alzheimer’s disease • Pyrrolindinoindoline physostigmine/eserethole Polonovski and Nitzberg, Bull. Soc. Chim. 1916, 19, 33. Figure from A. Audt, J. Chem. Educ. 2008, 85, 1524. Robinson: The first reported synthesis of physostigmine/eserethole Br CO2Et Me Na Me O O O O NaOH, then HCl Me CO2Et EtO2C HO N Br EtO2C N NK N O Br O O O O SOCl2 Me O Me O Me O Me O NH3 SnCl H2N N 2 N SOCl Cl N Cl N HCl 2 O N O N H O O O H + O SnCl2 Me O Me O O O Me SO Me N 2 4 Me N N N H EtO EtO N H O N + O O H O O NH2 N +N EtO Robinson was unable to Me resolve eserethole, and Me Me EtO EtO EtO therefore to confirm structure vs NH N NH2 Natural Product (WHY?) Me N H N N H + Robinson's d,l-noreserethole Described in 11 papers from 1932-1935, most recent is: d,l-eserethole King, F.
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