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Direct Catalytic Nucleophilic Substitution of Non- Derivatized Alcohols

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!"#$ #"%"" &' () * ( +#,-% . / % 0 ( % 1 !2 0 ( % 0 / 0 (/( % 1 342 . 50 - 6 7 % 8 3( / 9123 % . (( 0 ( . . 0 % :. 0 0 0 ( ( % . ;! 0% 8 4(- 6 7 / / 0 % 0 / 1<3!2% . (( ( 0 (( . . 0 % & 1 . 2 %:. 0 ;# %= 0 0 ( ( %9 0 0 0 - 6 7- 6 ( > ;! % !"#$ ?77 %% 7 @ A ?? ? ? #4,4!, 8-;B$CB#$,4BB#$$ 8-;B$CB#$,4BB#C4 ! (#",B# DIRECT CATALYTIC NUCLEOPHILIC SUBSTITUTION OF NON- DERIVATIZED ALCOHOLS Anon Bunrit Direct Catalytic Nucleophilic Substitution of Non-Derivatized Alcohols Anon Bunrit ©Anon Bunrit, Stockholm University 2017 ISBN print 978-91-7649-917-7 ISBN PDF 978-91-7649-918-4 Cover Image: ‘ALCOHOLS’ by Anon Bunrit Printed in Sweden by Universitetsservice US-AB, Stockholm 2017 Distributor: Department of Organic Chemistry, Stockholm University Life is a journey and full of possibility to make things possible. Abstract This thesis focuses on the development of methods for the activation of the hydroxyl group in non-derivatized alcohols in substitution reactions. The thesis is divided into two parts, describing three different catalytic systems. The first part of the thesis (Chapter 2) describes nucleophilic allylation of amines with allylic alcohols, using a palladium catalyst to generate un- symmetrical diallylated amines. The corresponding amines were further transformed by a one-pot ring-closing metathesis and aromatization reaction to afford β-substituted pyrroles with linear and branched alkyl, benzyl, and aryl groups in overall moderate to good yields. The second part (Chapters 3 and 4) describes the direct intramolecular stereospecific nucleophilic substitution of the hydroxyl group in enantioen- riched alcohols by Lewis acid and Brønsted acid/base catalysis. In Chapter 3, the direct intramolecular substitution of non-derivatized al- cohols has been developed using Fe(OTf)3 as catalyst. The hydroxyl groups of aryl, allyl, and alkyl alcohols were substituted by the attack of O- and N- centered nucleophiles, to provide five- and six-membered heterocycles in up to excellent yields with high enantiospecificities. Experimental studies showed that the reaction follows first-order dependence with respect to the catalyst, the internal nucleophile, and the internal electrophile of the sub- strate. Competition and catalyst-substrate interaction experiments demon- strated that this transformation proceeds via an SN2-type reaction pathway. In Chapter 4, a Brønsted acid/base catalyzed intramolecular substitution of non-derivatized alcohols was developed. The direct intramolecular and stereospecific substitution of different alcohols was successfully catalyzed by phosphinic acid (H3PO2). The hydroxyl groups of aryl, allyl, propargyl, and alkyl alcohols were substituted by O-, N-, and S-centered nucleophiles to generate five- and six-membered heterocycles in good to excellent yields with high enantiospecificities. Mechanistic studies (both experiments and density functional theory calculations) have been performed on the reaction forming five-membered heterocyclic compounds. Experimental studies showed that phosphinic acid does not promote SN1 reactivity. Rate-order determination indicated that the reaction follows first-order dependence with respect to the catalyst, the internal nucleophile, and the internal electrophile. DFT calculations corroborated with a reaction pathway in which the phos- phinic acid has a dual activation mode and operates as a bifunctional Brønsted acid/Brønsted base to simultaneously activate both the nucleophile and nucleofuge, resulting in a unique bridging transition state in an SN2-type reaction mechanism. ix x Populärvetenskaplig Sammanfattning Råmaterialet som används inom den kemiska sektorn är olefiner som erhålls från raffinering av råolja och vidare ”krackning”. Dessa föreningar framställs i samband med produktionen av bensin och diesel som en relativt liten sidoström. Vårt samhälle är otroligt beroende av denna lilla sidoström i produktion av mat, material och läkemedel. När samhället blir varse om de negativa konsekvenserna av att använda fossila källor samtidigt som tekniska framsteg görs för att begränsa behovet av flytande drivmedel och de stora oljekällorna håller på att sina så är det viktigt att hitta en alternativ och förnybar källa av råmaterial för att täcka våra behov. Alkoholer är kemiska föreningar som är naturligt förekommande i biomassa. I naturen så är de oftast optiskt rena. Inom kemin så nyttjas redan alkoholer som nukleofiler men om de ska användas som elektrofiler så behöver alkoholerna derivatiseras. Detta på grund av att den funktionella gruppen på alkoholer, hydroxylgruppen, är en dålig lämnande-grupp. Derivatiseringssteget gör inte bara syntesvägen längre utan leder till att det behövs extra reagens och att det bildas kemiskt avfall. Om hydroxylgruppen skulle kunna substitueras med en oladdad nukleofil så skulle endast vatten bildas som biprodukt. I den här avhandlingen så har jag undersökt hur hydroxylgruppen utan derivatisering kan substitueras av olika nukleofiler med hjälp av katalysatorer. I den första delen av denna avhandling så används allyliska alkoholer som reagens ihop med en amin. Genom att använda tre katalysatorer, så kan vi generera pyrroler, en viktig substans inom kemiindustrin med bara eten och vatten som biprodukt. I den andra delen av avhandlingen så har vi utvecklat två olika katalytiska system för att stereospecifikt substituera hydroxylgruppen på stereogena alkoholer med olika nukleofiler. I ett arbete så använder vi en järnkatalysator och i ett annat arbete så använder vi en Brønsted syra/bas katalysator. Förutom att lyckas substituera hydroxylgruppen i allyliska alkoholer så har vi även lyckats att substituera hydroxylgruppen i bensyl-, propargyl- och alkylalkoholer för första gången. Jag hoppas att resultaten från denna avhandling kommer att inspirera andra kemister att utveckla fler och effektivare metoder att substituera hydroxylgruppen så att vi på ett säkert sätt kan övergå till ett mer hållbart samhälle. xi xii List of Publications This thesis is based on the following publications and unpublished results, which are referred to in the text by their Roman numerals. The contribution by the author to each publication is clarified in Appendix A. Reprints were made with permission from the publishers, enumerated in Appendix B. I. A General Route to β-Substituted Pyrroles by Transition-Metal Catalysis Anon Bunrit, Supaporn Sawadjoon, Svetlana Tšupova, Per J. R. Sjöberg, Joseph S. M. Samec* J. Org. Chem., 2016, 81 (4), 1450–1460. (ChemInform, 2016, 47 (28)) II. Iron(III)-Catalyzed Intramolecular Stereospecific Substitution of the OH Group in Stereogenic Secondary and Tertiary Alcohols Rahul A. Watile, Anon Bunrit, Emi Lagerspets, Ingela Lanekoff, Srijit Biswas, Timo Repo,* Joseph S. M. Samec* Manuscript III. Brønsted Acid-Catalyzed Intramolecular Nucleophilic Substitu- tion of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer Anon Bunrit, Christian Dahlstrand, Sandra K. Olsson, Pemikar Srifa, Genping Huang, Andreas Orthaber, Per J. R. Sjöberg, Srijit Biswas,* Fahmi Himo,* Joseph S. M. Samec* J. Am. Chem. Soc., 2015, 137 (14), 4646–4649. (Synlett, 2016, 27 (02), 173–176) IV. H3PO2-Catalyzed Intramolecular Stereospecific Substitution of the Hydroxyl Group in Stereogenic Secondary Alcohols by N-, O-, and S-Centered Nucleophiles to Generate Heterocycles Anon Bunrit, Pemikar Srifa, Christian Dahlstrand, Genping Huang, Srijit Biswas, Fahmi Himo, Rahul A. Watile,* Joseph S. M. Samec* Manuscript xiii Parts of this thesis build upon Palladium and H3PO2-Catalyzed Nucleophilic Substitution of Non- Activated Alcohols Anon Bunrit, Licentiate Thesis, Department of Chemistry – BMC, Synthetic Organic Chemistry, Uppsala University, 2015. xiv Abbreviations Abbreviations and acronyms are used in agreement with the standards of the subject.* Additional non-standard and unconventional abbreviations that appear in this thesis are listed below: cat. catalyst CBS Corey-Bakshi-Shibata conv. conversion dba dibenzylideneacetone 1,2-DCE 1,2-dichloroethane DFT Density Functional Theory e.e. enantiomeric excess equiv. equivalent(s) er enantiomeric ratio e.s. enantiospecificity L ligand Nu nucleophile OH hydroxyl OTf trifluoromethanesulfonate PMP para-methoxyphenyl p-TSA, PTSA para-toluenesulfonic acid RCM Ring-Closing Metathesis rt room temperature TBAHS tetrabutylammonium hydrogensulfate TIPS triisopropylsilyl THP tetrahydropyranyl TS transition state SN1 unimolecular nucleophilic substitution SN2 bimolecular nucleophilic substitution SN′ nucleophilic substitution with allylic rearrangement * Coghill, A. M.; Garson, L. R. The ACS Style Guide: 3rd ed. American Chemical Society, 2006. xv xvi Table of Contents Abstract .................................................................................................................................... ix Populärvetenskaplig Sammanfattning ...................................................................................... xi List
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  • Oct 16 2018 Chem 261 Notes

    Oct 16 2018 Chem 261 Notes

    CHEM 261 October 9, 2018 RECALL: Identification of Chiral and Achiral (not chiral) compounds Example: Diaminopimelic acid - The above molecule is achiral even though there are stereogenic center (s), because there is symmetry within the molecule - These kinds of molecules are called meso compounds, which are compounds that contain stereocenters yet because of their symmetry, have mirror images that can be superimposed. - All achiral molecules, including meso compounds do not rotate polarized light (i.e. [α]D = 0) - Diaminopimelic acid - a component of bacterial cell wall and biosynthetic precursor to the amino acid known as lysine - this R,S diaminopimelic acid (above) is a diastereomer of the enantiomers (S,S or R,R diaminopimelic acid) below: Mirror O O O O C S C C R C HO S OH HO R OH NH2 NH2 NH2 NH2 chiral chiral Enantiomers A racemic mixture (racemate) of two enantiomers in a 1:1 ratio also has an [α]D = 0 Resolution of Enantiomers Definition: separation of two enantiomers - Requires a chiral reagent The starting material lactic acids are enantiomers of each other. By reacting enantiomers to make a salt with an enantiomer of MDMA (another chiral molecule), one can obtain salts which are now diastereomers of each other (RS and RR). The resulting diastereomers have different melting points, boiling points, solubilities, and can be separated by crystallization. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Substitution Reactions Remember: Radical Substitution light R-H + X2 R-X + H-X Proceeds by a radical mechanism Alkane X=F, Cl, Br Alkyl Halide Not I Ionic Substitution: M Nu: + R-X Nu-R + :X M Nucleophile Alkyl Halide (Seeks positive charge) Nucleophile is a subtsnace that seeks positive charge Types of Nucleophilic Substitution (SN) SN1 - rate depends on 1 concentration SN2 - The rate is dependent on the concentration of the nucleophile and the nucleophile (2 concentrations) Sn2 Mechanism Reverse reaction will not occur.