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Special Topic. Sulfur Going beyond the bad smell …. Gaëlle Mingat. 10/10/12. Sulfur , going beyond the bad smell … Overview. General properties Some name reactions involving sulfur Sulfur ylides and the Corey- Chaykovsky reaction Chiral sulfur

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  1. SpecialTopic Sulfur Goingbeyond the badsmell… Gaëlle Mingat 10/10/12

  2. Sulfur, goingbeyond the badsmell… Overview General properties Somenamereactionsinvolvingsulfur Sulfurylides and the Corey-Chaykovskyreaction Chiral sulfur Sulfur migration in organicsynthesis Sulfur in the foodindustry A « badsmell » example, just one… Sulfur in perfumes 10/10/12

  3. I. General properties • abundant, multivalent non-metal • cyclicoctatomicmolecule: S8 - Found in nature as the pure element, sulfide (S2-) and sulfate (SO42-) minerals - Either an oxidant or a reducing agent Bright yellowsolid Melting point: 115.21 °C, blood-redliquid Burns with a blueflamebetterobserved in the dark

  4. I. General properties • Once extractedfromsaltdomes: Fraschprocess • → 99.5% pure meltedproduct Carryingsulfur blocks from a volcano, Indonesia • Todayproduced as a by-product by removingorganosulfur compounds fromnaturalgas and petroleum Hydrodesulfurization R-S-R + 2H2 → 2 R-H + H2S Conversion of hydrogensulfide in elementalsulfur via the Claus process 3 O2 + 2 H2S → 2 SO2 + 2 H2O SO2 + 2 H2S → 3 S + 2 H2O Stockpiles of elementalsulfurrecoveredfromhydrocarbons, Alberta, Canada World production in 2011: 69 M tones → China (9.6), US (8.8), Canada (7.1), Russia (7.1) Dibenzothiophene, a composant of crudeoil

  5. I. General properties Electronic configurations: 6C 1s2 2s2 2p2 8O 1s2 2s2 2p4 16S 1s2 2s2 2p6 3s2 3p4 O: r = 70.2 pm S: r = 104.9 pm C-O: 355-380 kJ/mol C-S: 255 kJ/mol C=O: 678 kJ/mol C=S: 377 kJ/mol Longer and weaker bond Weakerπ bond (badoverlap) Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  6. I. General properties Electronegativities → electronaffinities, ionizationpotentials, bond energies Sanderson: «compactness » of an atom’selectroncloud → Polarizability of S  C-S bond: polarization not pronounced  Ioniccharacterlessened as compared to oxygencounterparts (hydrogenbondingless important)  Aromaticity: furan (Eres = 75kJ/mol) < thiophene < benzene (Eres = 113 kJ/mol) Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  7. I. General properties Essential element for life Cysteine Methionine Glutathione : antioxydant (Cysteine/Glycine/Glutamate) Disulfide bonds : mechanicalstrength, insolubility of keratin(hair, outer skin, feathers) and pungentodorwhenburned Thioesteracetyl coenzyme A Cystine (dehydrogenatedcysteine) 7

  8. I. General properties Essential element for life Biotin (vitamin H) Penicillincore structure Thiamine (vitamin B1) Umpolungchemistry in nature « S-adenosylmethionine »: Nature’siodomethane or diazomethaneequivalent Sulfanilamide (sulfadrug) 8

  9. I. General properties Important chemicalfunctionalities Thiols: R-SH Sulfides: R-S-R Sulfoxides Sulfones Sulfonicacids Sulfinicacids Sulfenicacids Sulfimides Sulfoximides Sulfonediimides Sulfonamides (sulfadrugs) Sulfinamides Sulfenamides Thiocarbonyls: thioamides

  10. I. General properties Important chemicalfunctionalities S-nitrosothiols Thiocyanates Isothiocyanates Sulfines [R3S]+ Sulfonium, oxosulfonium ion Sulfonium, oxosulfoniumylide

  11. II. Somenamereactionsinvolvingsulfur - Lawesson’sreagent: from a ketone to a thioketone → Enones, esters, lactones, amides, lactams, quinones - Sulfur as a reducing agent → NaHSO3, Na2SO3, Na2S2O3, Na2S·9H2O, SOCl2, SO2... → Me2S in ozonolysis to preventfurtheroxidation of products(stillused??) • Oxidationreactions • → Pfitzner-Moffatt • ▫ureabyproductsdifficult to remove • → Swern • ▫betteryields, fewersideproductsthan P-M • → Corey-Kim • ▫T > -25°C allowed but Me2S (toxic + badsmell) Kürti L., Czako B.; Strategic Applications of Named Reactions in Organic Synthesis (2005)

  12. II. Somenamereactionsinvolvingsulfur • Oxidationreactions • → Davis’ oxaziridineoxidations • ▫ 2-arylsulfonyl-3-aryloxaziridines • ▫sulfides and selenides to sulfoxides and selenoxides • ▫alkenes to epoxides • ▫ amines to hydroxylamines and amine oxides • ▫organometallic compounds to alcohols and phenols • ▫mostwidespread application: oxidation of enolates to α-hydroxycarbonyl compounds (acyloins) Kürti L., Czako B.; Strategic Applications of Named Reactions in Organic Synthesis (2005)

  13. II. Somenamereactionsinvolvingsulfur • Olefinations • → Bamford Stevens • ▫aproticsolvents: Z-alkenes major / proticsolvents: mixture of E- and Z-alkenes • → Shapiro • → Corey-Winter • → Julia-Lythgoe • ▫E-alkenes major Kürti L., Czako B.; Strategic Applications of Named Reactions in Organic Synthesis (2005)

  14. II. Somenamereactionsinvolvingsulfur • Rearrangements • → Mislow-Evans • → Pummerer • → Ramberg-Bäcklund • → Stevens • ▫ 1,2-rearrangement of a sulfoniumsaltgiving a sulfide, using a strong base Kürti L., Czako B.; Strategic Applications of Named Reactions in Organic Synthesis (2005)

  15. II. Somenamereactionsinvolvingsulfur → Barton-McCombie radical deoxygenationreaction ▫ radical substitution via a thiocarbonyl → Burgess dehydrationreaction → Chugaeveliminationreaction ▫ alkenesfromalcohols via a xanthate undergoing a syn-elimination → Corey-Nicolaoumacrolactonization Kürti L., Czako B.; Strategic Applications of Named Reactions in Organic Synthesis (2005)

  16. III. Sulfurylides and the Corey-Chaykovskyreaction Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  17. III. Sulfurylides and the Corey-Chaykovskyreaction Corey-Chaykovskyreaction: JACS1965, 87 (6), 1353 Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  18. III. Sulfurylides and the Corey-Chaykovskyreaction Enantio- and diastereocontrol in sulfurylides-mediatedepoxidations: Aggarwal’swork Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105) Aggarwal V.; Chem. Commun.2003, 2644

  19. III. Sulfurylides and the Corey-Chaykovskyreaction Examples of sulfurylidesmediatedasymmetricepoxidations Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105) Aggarwal V.; Chem. Commun.2003, 2644

  20. III. Sulfurylides and the Corey-Chaykovskyreaction The example of stabilizedylides(additional anion-stabilizing group): trans-diastereoselectivity Cross-over experiments:  Eitheranti- or syn-sulfoniumsaltfurnishesonly the trans-epoxidecontaining the more reactivealdehyde (p-NO2C6H4) →bothsyn- and anti-betaine are formedreversibly  Trans-selectivitybecausebarrier to torsional rotation in anti-betainesmaller Aggarwal V.; Chem. Commun.2003, 2644

  21. III. Sulfurylides and the Corey-Chaykovskyreaction Semi-stabilizedylides: trans-diastereoselectivity Cross-over experiments:  Anti-betainereactedwith a more reactivealdehyde: no incorporation of thisaldehyde in the final epoxide  Withsyn-betaine: complete incorporation of the more reactivealdehyde → Anti-betaineirreversiblyformed → Syn-betainereversiblyformed Aggarwal V.; Chem. Commun.2003, 2644

  22. III. Sulfurylides and the Corey-Chaykovskyreaction Control of enantioselectivity Formation of a single diastereoisomericsulfoniumylide High level of control of ylide conformation High level of control in face selectivity of the ylide Non-reversibility of the anti-betaine formation Aggarwal V.; Chem. Commun.2003, 2644

  23. III. Sulfurylides and the Corey-Chaykovskyreaction Control of enantioselectivity: effect of proticsolvents Aggarwal If lowenantioselectivity: Proticsolvents or addition of Li cations makes the reactionlessreversible (if reversibility of betaine formation is the cause) If lowdiastereoselectivity: Aproticsolvents and avoidance of species capable of solvatingalkoxides (increase of rotation barriersoreaction more reversible – displacementequilibrium to left) Aggarwal V.; Chem. Commun.2003, 2644

  24. IV. Chiral sulfur Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  25. IV. Chiral sulfur Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  26. IV. Chiral sulfur Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  27. IV. Chiral sulfur http://www.chemtube3d.com/Oppolzer.html Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  28. IV. Chiral sulfur Schaumann E.; Top Curr. Chem.2007, 274:1-34 (DOI 10.1007/128_2006_105)

  29. V. Sulfur migration in organicsynthesis Stuart Warren’swork; preliminary observation Warren S.; Phosphorous, Sulfur and Silicon1999, 153-154, 59

  30. V. Sulfur migration in organicsynthesis D. House, S. Warren: stereospecificity in the migration of « SPh » Secondary OH = LG Primary OH = Nu Secondary OH = LG Primary OH no more a Nu Warren S.; Phosphorous, Sulfur and Silicon1999, 153-154, 59

  31. V. Sulfur migration in organicsynthesis Competitionbetween 2 hydroxyl groups Is it possible to control which OH leaves, whichacts as a Nu and whereitattacks?? Primary OH = LG SPh = Nu Primary OH = LG Secondary OH = Nu Warren S.; Phosphorous, Sulfur and Silicon1999, 153-154, 59

  32. V. Sulfur migration in organicsynthesis Kineticresolution of racemic and enolisable 2-PhSaldehydes Warren S.; Phosphorous, Sulfur and Silicon1999, 153-154, 59

  33. VI. Sulfur in the foodindustry • About 10% of the volatile components detected in foods and beveragescontainsulfur •  Volatile organicsulfur compounds: extremelylowodourthreshold • →highly important for flavours and aromas Goeke A.; Sulfur reports2002, 23, 3, 243

  34. VI. Sulfur in the foodindustry The Maillard reactions (1911) ▫ chemicalreactionsoccuringwhile cooking food ▫ aminoacids + sugarsform a brownish mixture whenheated to hightemperature ▫ responsible for manycolors and flavors in foods: - the browning of variousmeatslike steak - toastedbread, burnishedcrust of brioche, cakes, yeast, biscuits - French fries, friedonions - maltedbarley (whiskey, beer) - dried or condensedmilk (dulce de leche) - maplesyrup - roasted coffee ▫ importance for the foodindustry in order to control the aspect, the taste and the conservation of food (incorrect preparation or storageproduce off-flavours)

  35. VI. Sulfur in the foodindustry Role of cysteine and cysteine-Sconjugates as odourprecursors Maillard reaction: cysteine + sugars (meatflavour…) Roastmeat Popcorn Basmati rice  Cheddar cheese: methanethiol, hydrogensulfide, dimethyldisulfide, dimethyltrisulfide → products of the catabolism of methionine and cysteine by bacteria Starkenmann C.; FlavourFragr. J.2008, 23, 369

  36. VI. Sulfur in the foodindustry Role of cysteine and cysteine-Sconjugates as odourprecursors  Wine and passion fruit Winetreatedwithcopper sulfate → « boxtree  » and « tropical fruit » odoursdisappeared Passion fruit aroma Aroma of youngbotrytizedsweetwines Cysteinylatedprecursors to typicalaroma of Sauvignon wines Starkenmann C.; FlavourFragr. J.2008, 23, 369

  37. VI. Sulfur in the foodindustry Sulfur compounds in wine → 5 families: thiols, sulfides, polysulfides, thioesters, heterocycles → 2 categories: boiling point below or above 90 °C (volatile compounds or less) → Produced by 2 main processes:  enzymatic: degradation of sulfur-containingamino-acids fermentation metabolism of sulfur-containing pesticides  non-enzymatic: photochemical, thermal, chemicalreactionsduringwinemaking and storage → Role of SO2: antibiotic and antioxydant (« contains sulfites »; up to 10mg/L) → Reactionsmoststudied: thosecatalyzed by light and producingunpleasantflavourscalled « light tastes » or « reduced tastes » Guasch J.; J. Chromath. A2000, 881, 569

  38. VI. Sulfur in the foodindustry Guasch J.; J. Chromath. A2000, 881, 569

  39. VI. Sulfur in the foodindustry

  40. VI. Sulfur in the foodindustry

  41. VI. Sulfur in the foodindustry Sulfur compounds in wine  In general, aromatic contributions of the above compounds considereddetrimental to winequality →cabbage, garlic, onion, rubber…  Somesulfur compounds contributeactively and are typical to somewinearomas →strawberry → box tree → passion fruit →cookedleeks Guasch J.; J. Chromath. A2000, 881, 569

  42. VII. A « badsmell » example, just one… → Humansweat Sweatsecreted by axillary glands odourless: odoriferous components generated by skin bacteria A tertiary thiol… Starkenmann C.; FlavourFragr. J.2008, 23, 369

  43. VIII. Sulfur in perfumes • Sulfur-containing compounds: some of the strongest odorants • Perception of odoroftendepends on: • → chemical, diastereo- and enantio-purity • → concentration (unpleasentodorwhensmelledathigh concentration) • ▫ ability to trigger differentreceptor sites in the olfactory bulb of the nose The cassis/cat example: 4-mercapto-4-methylpentanone 29 > 0.001%: obnoxious tom-cat urine off-odor (0.4% impurity in paint) < 0.00001%: naturalcrisp cassis note (Sauvignon wines) Also « Baie rouge » scent (raspberry), box tree, broom, green tea, grapefruit Goeke A.; Sulfur reports2002, 23, 3, 243

  44. VIII. Sulfur in perfumes • Structure-odorcorrelations • Free tertiarysulfur group distant of 2-4 Å of a carbonyl  Importance of stericbulkaroundsulfur group (tertiarymercaptoketones)  Importance of H bonding 61: no fruityodor 62: less cassis-likethan63 Goeke A.; Sulfur reports2002, 23, 3, 243

  45. VIII. Sulfur in perfumes •  Importance of diastereo- and enantio- purity • Hydrolysis of thioacetates in the mucosa of the olfactory bulb responsible for cassis odor in 38? Goeke A.; Sulfur reports2002, 23, 3, 243

  46. VIII. Sulfur in perfumes Grapefruit 1982: 1-p-menthene-8-thiol shown to be an extremelypotent constituent of grapefruit juice. Alsoidentified in orange, yuzu and must.

  47. VIII. Sulfur in perfumes Passionfruit Oxane® (perfumery) 62, 63: also in white and redwines Goeke A.; Sulfur reports2002, 23, 3, 243

  48. VIII. Sulfur in perfumes Green scents Fancy « tomatoleaves » scent in the perfume « Les Belles » (Nina Ricci): complexcombination of several odorants. Essential oil of coriander, used in fine fragrances: « Gucci No. 1 », « Le Jardin d’Amour », « Coriandre » (!) Goeke A.; Sulfur reports2002, 23, 3, 243

  49. VIII. Sulfur in perfumes Scents of flowers Goeke A.; Sulfur reports2002, 23, 3, 243

  50. VIII. Sulfur in perfumes The archetypalexample: rose oil Impartnaturalness of rose scentperceivedwhensmelling rose petals to essential rose oil Goeke A.; Sulfur reports2002, 23, 3, 243

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