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Ethers, Sulfides and Epoxides

Structure, nomenclature, properties Ether synthesis - Williamson synthesis ( S N 2 ) H + /ROH addition to olefins ( chapt 6) Reactions - acid catalyzed cleavage of ethers ( S N 2/S N 1/E1 ) [oxidation out ] Ethers as Protecting Groups (Gps) . Epoxides - oxirane nomenclature

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Ethers, Sulfides and Epoxides

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  1. Structure, nomenclature, properties Ether synthesis - Williamson synthesis(SN2) H+/ROH addition to olefins (chapt 6) Reactions - acid catalyzed cleavage of ethers (SN2/SN1/E1) [oxidation out] Ethers as Protecting Groups (Gps). Epoxides - oxirane nomenclature Preparation: epoxidation,halohydrin Reactions - nucleophilic cleavage (SN2/SN1/E1) [sulfides out] Synthesis (continued) chapter 11 Ethers, Sulfides and Epoxides [blue - repeat of earlier chemistry] ss12 19

  2. Chapter 11 Chapter 15 synthesis synthesis sources nomenclature properties reactions substitution protecting groups epoxides epoxide reaction

  3. diethyl ether tetrahydrofuran or THF dihydropyran Ethers, Sulfides and Epoxides - 11 Structure - tetrahedral (sp3) oxygen & carbon

  4. Ethers, Sulfides and Epoxides - 11 Nomenclature - ether group is a substituent 2-cyclopentenol 4-ethoxy-2-cyclopentenol (1S,4R)-4-ethoxy-2-cyclopenten-1-ol

  5. Hydrogen bond acceptor (Lewis base) Ethers, Sulfides and Epoxides - 11 Properties - polar C-O covalent bonds But low dielectric constant

  6. Ethers, Sulfides and Epoxides - 11 Two ways to prep benzyl ethyl ether Williamson ether synthesis SN2 substitution recall similar problems in chapter 9 (9.46, 9.48 and 9.49)

  7. Ethers, Sulfides and Epoxides - 11 H+/ROH addition to olefins, “hydration-like” Familiar? Recall/review addition problems 6.29, 6.34a

  8. Reactions - acid catalyzed cleavage of ethers SN1/E1 SN2 Ethers, Sulfides and Epoxides - 11

  9. Chapter 11 Chapter 15 synthesis synthesis sources nomenclature properties reactions substitution protecting groups epoxides epoxide reaction

  10. Ethers, Sulfides and Epoxides - 11 Ethers Protecting Groups (ref. problems 6.33) Problem 6.33: alcohol “interferes” with Br2 addition

  11. Ethers, Sulfides and Epoxides - 11 Ether Protecting Groups (ref. problems 6.33) 3 1 2 Problem 6.33: alcohol “interferes” with Br2 addition protecting group (Pg) = blocking group

  12. Ethers, Sulfides and Epoxides - 11 Protecting groups characteristics 3 1 On efficient Inert to rx Off efficient 2 Problem 6.33: alcohol “interfers” with Br2 addition. protecting group (Pg) = blocking group

  13. Ethers, Sulfides and Epoxides - 11 TMSethers

  14. Ethers, Sulfides and Epoxides - 11

  15. Cyclic polyethers The parent name is crown, preceded by a number describing the size of the ring followed by the number of oxygen atoms in the ring, e.g 18-crown-6 Crown Ethers - not covered O O O O O O

  16. Ethers, Sulfides andEpoxides - 11 Nomenclature - epoxy (substituent) oroxirane ether 4,5-epoxycycloheptene (4S,5R)-4,5-epoxycycloheptene

  17. Ethers, Sulfides and Epoxides - 11 Prep of epoxides/oxiranes

  18. Ethers, Sulfides and Epoxides - 11 Prep of epoxides - better mechanistic view stereospecific like bromine addition

  19. other epoxide sources - halohydrins/base mechanism intramolecular “SN2” See problem 9.50, same reaction

  20. :B Other sources of epoxides - halohydrins/base chapter 6

  21. Reactions of epoxides: H+ or LA Opening B: or LB Opening

  22. Reactions of epoxides: H+ or LA Opening mechanism?

  23. Reactions of epoxides: B: or LB Opening mechanism?

  24. Recall: 1,2-cisdiol Stereochemistry 1,2-transdiol

  25. 3o more hindered 1o-less hindered proton source Regioselectivity SN2 like

  26. Regioselectivity SN1 like

  27. Regioselectivity

  28. example epoxyresin

  29. Application of Epoxy Chemistry

  30. amine epoxide Application of Epoxy Chemistry

  31. Application of Epoxy Chemistry

  32. Application of Epoxy Chemistry

  33. Application of Epoxy Chemistry

  34. like sodium borohydride lithium aluminum hydride

  35. Organometallic Compounds (R-M) Organomagnesium & Organolithium compds 15.1 Lithium Diorganocopper (Gilman) Reagents 15.2 Not covered: Organopalladium reagents, Heck reaction, carbenes, carbenoids, & alkene metathesis. Synthesis, Concepts and the Final

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