DOCSLIB.ORG

Cooperative Dual Catalysis with Thiourea Organocatalysts

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cooperative Dual Catalysis with Thiourea Organocatalysts COOPERATIVE DUAL CATALYSIS WITH THIOUREA ORGANOCATALYSTS By CHENFEI ZHAO A dissertation submitted to the Graduate School-New Brunswick Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Doctor of Philosophy Graduate Program in Chemistry and Chemical Biology Written under the direction of Professor Daniel Seidel And approved by _____________________________________ _____________________________________ _____________________________________ _____________________________________ New Brunswick, New Jersey October, 2017 ABSTRACT OF THE DISSERTATION Cooperative Dual Catalysis with Thiourea Organocatalysts by CHENFEI ZHAO Dissertation Director: Professor Daniel Seidel Thiourea organocatalysis represents a versatile activation strategy in synthetic organic chemistry. By hydrogen-bonding interactions with neutral or anionic substrates and/or intermediates, thiourea organocatalysts can often direct the reaction pathways with promising levels of stereochemical control. This dissertation demonstrates the cooperative use of thiourea organocatalysts in combination with other types of catalysts in addressing challenging synthetic problems that are not realized by either type alone. Specifically, cooperative catalysis of thiourea and iminium organocatalysts enabled the first highly enantioselective direct oxa-Pictet–Spengler reactions under weakly acidic conditions. In combination with a transition metal catalyst, an acid–thiourea catalyst afforded highly enantioselective A3 reactions with secondary amines. Strong Brønsted acid was also applied cooperatively with thiourea organocatalyst, furnishing the direct reductive etherification reactions with a wide variety of substrates. ii ACKNOWLEDGEMENTS Parts of chapter II were adapted from the article “Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions: Catalytic Enantioselective Oxa-Pictet–Spengler Reactions” (J. Am. Chem. Soc. 2016, 138, 9053). Parts of chapter III were adapted from the article “Enantioselective A3 Reactions of Secondary Amines with a Cu(I)/Acid-Thiourea Catalyst Combination” (J. Am. Chem. Soc. 2015, 137, 4650). Parts of chapter IV were adapted from the article “Reductive Etherification via Anion-Binding Catalysis” pending publication. I’d like to express my great gratitude to my advisor Professor Daniel Seidel, for his guidance and support throughout my graduate studies. I really appreciate his patience and the great amount of time he has spent on me, not only in helping me excel in research but also in acquiring opportunities for my future development. It has been highly enjoyable and encouraging to work for Professor Seidel, whose goals and priorities often align with my own. I also want to thank my committee members Professor Lawrence Williams, Professor Alan Goldman, Professor Kai Hultzsch and my outside committee member Dr. Blair Wood, for their invaluable time and advices, which have significantly inspired my ways of thinking and carrying out research. I am also grateful to the Seidel group members from the past and present, for their support throughout my graduate studies. I would like to especially thank Dr. Longle Ma, for teaching me and familiarizing me with the lab in many aspects during my very early days here. My progress in research is also inseparable from the help provided by Dr. Tom Emge, Dr. Nagarajan Murali and Dr. Alexei Ermakov and I deeply appreciate their professionalism and passion. I deeply thank my parents, for their love, support and understanding of me pursuing my career far away from home. iii Table of Contents ABSTRACT OF THE DISSERTATION ........................................................................................ ii ACKNOWLEDGEMENTS ............................................................................................................ iii Chapter I Introduction to Cooperative Multiple Catalysis ............................................................... 1 1.1 Organocatalysis ................................................................................................................ 1 1.1.1 Thiourea Organocatalysis ........................................................................................ 1 1.2 Cooperative Multiple Catalysis ........................................................................................ 6 1.2.1 Cooperative Multiple Catalysis with Organocatalysts and Transition Metal Catalysts ................................................................................................................................. 8 1.2.2 Cooperative Multiple Catalysis with Organocatalysts ........................................... 12 1.3 Objectives ...................................................................................................................... 19 References .................................................................................................................................. 20 Chapter II Cooperative Dual Catalysis Enables Direct Formation of Oxocarbenium Ions ........... 22 2.1 Background .................................................................................................................... 22 2.2 Concept .......................................................................................................................... 26 2.3 Catalytic Enantioselective Oxa-Pictet–Spenger Reactions ............................................ 27 2.3.1 Background ............................................................................................................ 27 2.3.2 Optimization .......................................................................................................... 29 2.3.3 Substrate Scope ...................................................................................................... 37 2.3.4 Further Mechanistic Studies................................................................................... 38 2.4 Catalytic Enantioselective Acetalization Reactions ....................................................... 40 2.5 Related Systems Using Acetal/Ketal as Carbonyl Surrogate ......................................... 42 iv 2.5.1 Catalytic Enantioselective Oxa-Pictet–Spengler Reactions towards Tetra- substituted Stereogenic Centers ............................................................................................. 43 2.5.2 Catalytic Enantioselective Indole Additions to Oxocarbenium Ions ..................... 45 2.5.3 Catalytic Enantioselective Reduction of Isochroman Ketals. ................................ 46 2.6 Summary ........................................................................................................................ 49 Experimental Section ................................................................................................................. 51 References .................................................................................................................................. 71 Chapter III Metal/Acid–Thiourea Cooperative Dual Catalysis ..................................................... 74 3.1 Background .................................................................................................................... 74 3.1.1 A3 Reactions ........................................................................................................... 74 3.1.2 Conjugate-Base-Stabilized Brønsted Acids ........................................................... 77 3.2 Enantioselective A3 Reactions of Secondary Amines with a Cu(I)/Acid−Thiourea Catalyst Combination................................................................................................................. 78 3.2.1 Optimization .......................................................................................................... 79 3.2.2 Substrate Scope ...................................................................................................... 84 3.3 Transformation of A3 Products to Enantioenriched Allenes .......................................... 86 3.3.1 Background ............................................................................................................ 86 3.3.2 Results and Discussion .......................................................................................... 88 3.4 Summary ........................................................................................................................ 89 Experimental Section ................................................................................................................. 90 References ................................................................................................................................ 114 v Chapter IV Direct Reductive Etherification Enabled by Cooperative Dual Catalysis of a Thiourea and a Strong Brønsted Acid ......................................................................................................... 116 4.1 Background .................................................................................................................. 116 4.1.1 Williamson Ether Synthesis ................................................................................. 116 4.1.2 Reduction of Acetals ............................................................................................ 117 4.1.3 Reductive Etherification ...................................................................................... 119 4.2 Direct Reductive Etherification Reactions Enabled by a Thiourea and a Strong Brønsted Acid Combination
Load more

Recommended publications
  • Aldrich FT-IR Collection Edition I Library
    Aldrich FT-IR Collection Edition I Library Library Listing – 10,505 spectra This library is the original FT-IR spectral collection from Aldrich. It includes a wide variety of pure chemical compounds found in the Aldrich Handbook of Fine Chemicals. The Aldrich Collection of FT-IR Spectra Edition I library contains spectra of 10,505 pure compounds and is a subset of the Aldrich Collection of FT-IR Spectra Edition II library. All spectra were acquired by Sigma-Aldrich Co. and were processed by Thermo Fisher Scientific. Eight smaller Aldrich Material Specific Sub-Libraries are also available. Aldrich FT-IR Collection Edition I Index Compound Name Index Compound Name 3515 ((1R)-(ENDO,ANTI))-(+)-3- 928 (+)-LIMONENE OXIDE, 97%, BROMOCAMPHOR-8- SULFONIC MIXTURE OF CIS AND TRANS ACID, AMMONIUM SALT 209 (+)-LONGIFOLENE, 98+% 1708 ((1R)-ENDO)-(+)-3- 2283 (+)-MURAMIC ACID HYDRATE, BROMOCAMPHOR, 98% 98% 3516 ((1S)-(ENDO,ANTI))-(-)-3- 2966 (+)-N,N'- BROMOCAMPHOR-8- SULFONIC DIALLYLTARTARDIAMIDE, 99+% ACID, AMMONIUM SALT 2976 (+)-N-ACETYLMURAMIC ACID, 644 ((1S)-ENDO)-(-)-BORNEOL, 99% 97% 9587 (+)-11ALPHA-HYDROXY-17ALPHA- 965 (+)-NOE-LACTOL DIMER, 99+% METHYLTESTOSTERONE 5127 (+)-P-BROMOTETRAMISOLE 9590 (+)-11ALPHA- OXALATE, 99% HYDROXYPROGESTERONE, 95% 661 (+)-P-MENTH-1-EN-9-OL, 97%, 9588 (+)-17-METHYLTESTOSTERONE, MIXTURE OF ISOMERS 99% 730 (+)-PERSEITOL 8681 (+)-2'-DEOXYURIDINE, 99+% 7913 (+)-PILOCARPINE 7591 (+)-2,3-O-ISOPROPYLIDENE-2,3- HYDROCHLORIDE, 99% DIHYDROXY- 1,4- 5844 (+)-RUTIN HYDRATE, 95% BIS(DIPHENYLPHOSPHINO)BUT 9571 (+)-STIGMASTANOL
    [Show full text]
  • CPY Document
    3. eHEMieAL eOMPOSITION OF ALeOHOLie BEVERAGES, ADDITIVES AND eONTAMINANTS 3.1 General aspects Ethanol and water are the main components of most alcoholIc beverages, although in some very sweet liqueurs the sugar content can be higher than the ethanol content. Ethanol (CAS Reg. No. 64-17-5) is present in alcoholic beverages as a consequence of the fermentation of carbohydrates with yeast. It can also be manufactured from ethylene obtained from cracked petroleum hydrocarbons. The a1coholic beverage industry has generally agreed not to use synthetic ethanol manufactured from ethylene for the production of alcoholic beverages, due to the presence of impurities. ln order to determine whether synthetic ethanol has been used to fortify products, the low 14C content of synthetic ethanol, as compared to fermentation ethanol produced from carbohydrates, can be used as a marker in control analyses (McWeeny & Bates, 1980). Some physical and chemical characteristics of anhydrous ethanol are as follows (Windholz, 1983): Description: Clear, colourless liquid Boilng-point: 78.5°C M elting-point: -114.1 °C Density: d¡O 0.789 It is widely used in the laboratory and in industry as a solvent for resins, fats and oils. It also finds use in the manufacture of denatured a1cohol, in pharmaceuticals and cosmetics (lotions, perfumes), as a chemica1 intermediate and as a fuel, either alone or in mixtures with gasolIne. Beer, wine and spirits also contain volatile and nonvolatile flavour compounds. Although the term 'volatile compound' is rather diffuse, most of the compounds that occur in alcoholIc beverages can be grouped according to whether they are distiled with a1cohol and steam, or not.
    [Show full text]
  • Enhancing the Yields of Phenolic Compounds During Fermentation Using Saccharomyces Cerevisiae Strain 96581
    Food and Nutrition Sciences, 2014, 5, 2063-2070 Published Online November 2014 in SciRes. http://www.scirp.org/journal/fns http://dx.doi.org/10.4236/fns.2014.521218 Enhancing the Yields of Phenolic Compounds during Fermentation Using Saccharomyces cerevisiae Strain 96581 Adam A. Banach, Beng Guat Ooi* Department of Chemistry, Middle Tennessee State University, Murfreesboro, TN, USA Email: *[email protected] Received 2 September 2014; revised 28 September 2014; accepted 15 October 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Phenylethanol, tyrosol, and tryptophol are phenolic compounds or fusel alcohols formed via the Ehrlich pathway by yeast metabolism. These compounds can yield health benefits as well as con- tribute to the flavors and aromas of fermented food and beverages. This research shows that Sac- charomyces cerevisiae Strain 96581 is capable of producing significantly higher levels of these three compounds when the precursor amino acids were supplemented into either the Chardonnay concentrate for wine-making or the malt concentrate for brewing English Ale. Strain 96581 can produce phenylethanol, tyrosol, and tryptophol as high as 434 mg/kg, 365 mg/kg, and 129 mg/kg, respectively, in the beer fermentation. The performance of Ale yeast WLP002 from White Labs Inc. was also analyzed for comparison. Strain 96581 outperformed WLP002 in the control beer, the amino acids supplemented beer, and the kiwi-beer background. This shows that Strain 96581 is more effective than WLP002 in converting the malt and the kiwi fruit supplements via its endo- genous enzymes.
    [Show full text]
  • Development of Enantioselective Organocatalysis by Bifunctional Indane Amine-Thiourea Catalyst
    DEVELOPMENT OF ENANTIOSELECTIVE ORGANOCATALYSIS BY BIFUNCTIONAL INDANE AMINE-THIOUREA CATALYST REN QIAO NATIONAL UNIVERSITY OF SINGAPORE 2013 DEVELOPMENT OF ENANTIOSELECTIVE ORGANOCATALYSIS BY BIFUNCTIONAL INDANE AMINE-THIOUREA CATALYST REN QIAO (B.Sc., Sichuan Univ.) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2013 To my parents for their endless love, support and encouragement PHD DISSERTATION 2013 REN QIAO Thesis Declaration I hereby declare that this thesis is my original work and it has been written by me in its entirety, under the supervision of A/P Wang Jian, Chemistry Deparrtment, National University of Singapore, between 08/2009 and 09/2013. I have duly acknowledged all the sources of information which have been used in the thesis. This thesis has also not been submitted for any degree in any university previously The contents of the thesis have been partly published in: 1. Qiao Ren, Jian Wang. Asian J. Org. Chem. 2013, 2, 542. 2. Qiao Ren, Jiayao Huang, Lei Wang, Wenjjun Li, Hui Liu, Xuefeng Jiang, Jian Wang. ACS Catal. 2012, 2, 2622. 3. Qiao Ren, Woon-Yew Siau, Zhiyun Du, Kun Zhang, Jian Wang. Chem. –Eur. J. 2011, 17, 7781. 4. Qiao Ren, Yaojun Gao, Jian Waanng. Org. Biomol. Chem. 2011, 9, 5297. 5. Qiao Ren, Yaojun Gao, Jian Waanng. Chem. –Eur. J. 2010, 16, 13594. Ren Qiao 2014/003/07 Name Signature Date i PHD DISSERTATION 2013 REN QIAO Acknowledgements It is my great pleasure to express my deepest gratitude and appreciation to all the people who have helped and inspired me during my four-year PhD studies in Department of Chemistry, National University of Singapore (NUS).
    [Show full text]
  • Quantification of Catalytic Activity for Electrostatically Enhanced Thioureas Via Reaction Kinetics and a UV−Vis Spectroscopic
    Quantification of Catalytic Activity for Electrostatically Enhanced Thioureas via Reaction Kinetics and a UV−Vis Spectroscopic Measurement Yang Fan, Curtis Payne and Steven R. Kass* Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States E-mail: [email protected] Table of Content Graphic S R O N N R H N thiourea H Ph N O N CH2Cl2 N Ph Δλ < 0 max N N S S thiourea 10 thioureas examined, rates span >104 and blue shifts correlate with the rate 1 ABSTRACT Charged thiourea derivatives containing one and two methylated or octylated pyridinium ion centers and a tetraarylborate or triflate counteranion are reported. These novel catalysts are much more active in the Friedel‒Crafts reactions of trans-β-nitroalkenes with N-methylindoles than the privileged N,N'-bis(3,5-bis(trifluoromethyl)phenyl)thiourea (i.e., Schreiner’s thiourea) by up to 2-3 orders of magnitude. A previously reported UV-Vis spectroscopic method by Kozlowski et al. was exploited to rationalize their reactivity order along with non-charged analogs. These results offer a new design strategy for organocatalysts by introducing positively charged centers without adding additional N–H, O–H, or S–H hydrogen bond donor sites. 2 INTRODUCTION Nature exploits noncovalent interactions such as hydrogen bonds to reduce the activation energy barriers of enzyme-catalyzed chemical transformations.1 A wealth of small-molecule organocatalysts that mimic this behavior have been developed over the past two decades and this field has emerged
    [Show full text]
  • Price-List 2012-13
    Sanjay International Price-List 2012-13 Sanjay International Mr. Sanjay Mital +(91)-9810163421 No. 3439/5, Gali Bajrang Bali Chawri Bazar - Delhi, Delhi - 110 006, India http://www.indiamart.com/sanjayinternational/ Sanjay International Terms of Sale PRICES : Prices mentioned in the Price List are ruling at the time of printing of the Price List and subject to change without prior notice. Goods shall be invoice at prices ruling on the date of dispatch. TAXES & DUTIES : Sales Tax, MVAT, Octrio Duty, other Duties & Levies will be charged extra as applicable at the time of supply. For exemption of Sales Tax & Octrio Exemption Certificate should be sent along with order. PAYMENTS : Payments are to be made by Demand draft / cheques drawn on 'Sanjay international.' payable at Delhi. In the event of payment through bank the customer has to retire the documents immediately on presentation of the documents by the bank. The interest @21% will be charged on all the payments received after due dates. BULK REQUIREMENTS : Requirements/Enquiries for bulk packing and large quantities for any items will be considered. INSURANCE : Goods are packed with utmost care and forwarded at Customer's risk. No responsibility is taken for breakages or loss in transit. Goods can be insured at the customer's request at 1% of the invoice value. Charges for insurance will be made in the invoice itself. MINIMUM ORDER : All orders invoiced over Rs.25,000/- net shall be dispatched F.O.R. Delhi by transport, freight extra. Goods can be dispatched by Post, courier/angadia or by Passenger Train on customer's request freight will be born by customer.
    [Show full text]
  • A Catalytic Asymmetric Total Synthesis of (−)-Perophoramidine
    Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue A catalytic asymmetric total synthesis of (À)-perophoramidine† Cite this: Chem. Sci.,2015,6,349 B. M. Trost,* M. Osipov, S. Kruger¨ and Y. Zhang We report a catalytic asymmetric total synthesis of the ascidian natural product perophoramidine. The synthesis employs a molybdenum-catalyzed asymmetric allylic alkylation of an oxindole nucleophile and a monosubstituted allylic electrophile as a key asymmetric step. The enantioenriched oxindole product from this transformation contains vicinal quaternary and tertiary stereocenters, and is obtained in high yield along with high levels of regio-, diastereo-, and enantioselectivity. To install the second quaternary Received 19th June 2014 stereocenter in the target, the route utilizes a novel regio- and diastereoselective allylation of a cyclic Accepted 30th July 2014 imino ether to deliver an allylated imino ether product in near quantitative yield and with complete DOI: 10.1039/c4sc01826e regio- and diastereocontrol. Oxidative cleavage and reductive amination are used as final steps to access www.rsc.org/chemicalscience the natural product. Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Introduction while that of the communesins is cis. From a biological perspective, perophoramidine (1) displays cytotoxicity against m In 2002, Ireland and coworkers reported the isolation and the HCT116 colon carcinoma cell line with an IC50 of 60 M. structural elucidation of a novel polycyclic alkaloid, (+)-per- The combination of its complex, densely functionalized struc- ophoramidine (1) from the Philippine ascidian organism Per- ture and cytotoxic properties make perophoramidine (1)an ophora namei (Fig. 1).1 The structure of (+)-perophoramidine (1) attractive target for asymmetric total synthesis.
    [Show full text]
  • Bioactive Metabolites of Bulbine Natalensis (Baker): Isolation, Characterization, and Antioxidant Properties
    Bioactive metabolites of Bulbine natalensis (Baker): Isolation, characterization, and antioxidant properties Olusola Bodede1,2, Nomfundo Mahlangeni2, Roshila Moodley2, Manimbulu Nlooto1, Elizabeth Ojewole1 1Discipline of Pharmaceutical Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, 4000, KwaZulu-Natal, South Africa, 2School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban, 4000, South Africa Abstract Background: Medicinal plants continue to play a key role in disease management and modern drug development. ORIGINAL ARTICLE ORIGINAL Bulbine natalensis is one of several South Africa’s indigenous succulent medicinal species. B. natalensis’ high medicinal profile has made it a commercially-available herb within the South African market and beyond. However, there is a limited scientific report on its bioactive metabolites. Objectives: This study’s objective was to isolate and identify bioactive compounds from B. natalensis leaves and evaluate the compounds and crude extracts for antioxidant activity. Materials and Methods: Fractionation and purification of B. natalensis dichloromethane extract were done using chromatographic techniques. Whole extract profiling was carried out on dichloromethane and methanol extracts using gas chromatography-mass spectrometry (GC-MS). The isolated compounds and extracts were evaluated for antioxidant activity. Results: The dichloromethane extract yielded two pentacyclic triterpenes (glutinol and taraxerol), one tetracyclic triterpene
    [Show full text]
  • Nicolet Standard Collection of FT-IR Spectra
    Nicolet Standard Collection of FT-IR Spectra Library Listing – 3,119 spectra This collection is suited to the needs of analytical services and investigational laboratories. It provides a wide array of common chemicals in a lower cost package and can be used in combination with the Nicolet Standard Collection of FT-Raman Spectra to provide analysts a higher degree of confidence when identifying unknowns. The Nicolet Standard Collection of FT-IR Spectra includes 3,119 spectra of common chemicals with representatives of major functional groups and combinations of functional groups. It contains the same chemical series available in the Nicolet Standard Collection of FT-Raman Spectra. These matched libraries can be used alone or in combination with Thermo Fisher’s unique OMNIC Linked Search software. Nicolet Standard Collection of FT-IR Spectra Index Compound Name Index Compound Name 1177 (+)-1,4-Androstadiene-3,17-dione 1498 (+/-)-Ketamine .HCl; 2-(2- 140 (+)-11a-Hydroxyprogesterone, 95% Chlorophenyl)-2- 1221 (+)-2'-Deoxyuridine, 99+% (methylamino)cyclohex 2999 (+)-2,3-O-Benzylidene-D-threitol 1104 (+/-)-Octopamine .HCl, 98% 1291 (+)-2-Phenyl-1-propanol, 97% 2541 (+/-)-Pantothenol 933 (+)-3-Nitro-L-tyrosine, 99% 2058 (+/-)- 833 (+)-4-Cholesten-3-one Tetracyclo[6.6.2.0(2,7).0(9,14)]hexadec 739 (+)-6-Aminopenicillanic acid, 96% a-2,4,6,9,11,13-he 2361 (+)-Arabinogalactan 579 (+/-)-a-Benzoin oxime, 99% 2545 (+)-Boldine .HCl; 1,10- 2290 (+/-)-cis-2-Methylcyclohexanol, 97% Dimethoxyaporphine-2,9-diol .HCl 2287 (+/-)-trans-1,2-Dibromocyclohexane,
    [Show full text]
  • Catalytic Enantioselective Approaches to the Oxa-Pictet–Spengler Cyclization and Other 3,6-Dihydropyran-Forming Reactions
    SYNOPEN2509-9396 Georg Thieme Verlag Stuttgart · New York 2019, 3, 77–90 short review 77 en Syn Open Z. Zhu et al. Short Review Catalytic Enantioselective Approaches to the oxa-Pictet–Spengler Cyclization and Other 3,6-Dihydropyran-Forming Reactions Zhengbo Zhua HO HO Brønsted acid Alafate Adilia OH catalysis O Chenfei Zhaob 0000-0003-3960-3047 up to R Daniel Seidel*a 0000-0001-6725-111X RCHO 99% ee a Center for Heterocyclic Compounds, Department of Chemis- Dual anion-binding OH O try, University of Florida, Gainesville, Florida 32611, USA iminium catalysis [email protected] N N H H b Department of Chemistry, University of California–Berkeley; R Materials Sciences Division, Lawrence Berkeley National Labo- up to 95% ee ratory; Kavli Energy NanoSciences Institute at Berkeley; Berke- ley Global Science Institute, Berkeley, California 94720, USA Received: 24.08.2019 aryl substituent.9 In this Short Review, we provide exam- Accepted after revision: 04.09.2019 ples of asymmetric oxa-Pictet–Spengler cyclizations that Published online: 25.09.2019 DOI: 10.1055/s-0039-1690686; Art ID: so-2019-d0023-r are under substrate control, discuss all known catalytic en- License terms: antioselective variants of the oxa-Pictet–Spengler cycliza- 10 © 2019. The Author(s). This is an open access article published by Thieme under the tion, and provide an overview of other catalytic enanti- terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, oselective reactions that lead to isochromans and tetrahy- permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes or adapted, remixed, dropyrano[3,4-b]indoles.
    [Show full text]
  • Nicolet Vapor Phase
    Nicolet Vapor Phase Library Listing – 8,654 spectra This library is one the most comprehensive collections of vapor phase FT-IR spectra. It is an invaluable tool for scientist involved in investigations on gas phase materials. The Nicolet Vapor Phase Library contains 8654 FT-IR spectra of compounds measured in gas phase. Most spectra were acquired by the Sigma-Aldrich Co. using product samples. Additional spectra were collected by Hannover University, University of Wurzburg and Thermo Fisher Scientific applications scientists. Spectra were collected using sampling techniques including heated or room temperature gas cell or a heated light-pipe connected to the outlet of a gas chromatograph. Nicolet Vapor Phase Index Compound Name Index Compound Name 8402 ((1- 5457 (-)-8-Phenylmenthol; (-)-(1R,2S,5R)-5- Ethoxycyclopropyl)oxy)trimethylsilane Methyl-2-(2-phenyl-2-propyl)cyc 4408 (+)-1,3-Diphenylbutane 1095 (-)-Carveol, mixture of isomers; p- 4861 (+)-1-Bromo-2,4-diphenylbutane Mentha-6,8-dien-2-ol 2406 (+)-3-(Heptafluorobutyryl)camphor 3628 (-)-Diisopropyl D-tartrate 2405 (+)-3-(Trifluoroacetyl)camphor 1427 (-)-Limonene oxide, cis + trans; (-)-1,2- 281 (+)-3R-Isolimonene, trans-; (1R,4R)- Epoxy-4-isopropenyl-1-methyl (+)-p-Mentha-2,8-diene 1084 (-)-Menthol; [1R-(1a,2b,5a)]-(-)-2- 289 (+)-Camphene; 2,2-Dimethyl-3- Isopropyl-5-methylcyclohexanol methylenebicyclo[2.2.1]heptane 2750 (-)-Menthoxyacetic acid 3627 (+)-Diisopropyl L-tartrate 1096 (-)-Myrtanol, cis-; (1S,2R)-6,6- 2398 (+)-Fenchone; (+)-1,3,3- Dimethylbicyclo[3.1.1]heptane-2-metha
    [Show full text]
  • Uva-DARE (Digital Academic Repository)
    UvA-DARE (Digital Academic Repository) Fluorogenic organocatalytic reactions Raeisolsadati Oskouei, M. Publication date 2017 Document Version Other version License Other Link to publication Citation for published version (APA): Raeisolsadati Oskouei, M. (2017). Fluorogenic organocatalytic reactions. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:01 Oct 2021 Chapter 1 1 Chapter 1 Introduction 1.1. Organocatalysis Catalyst, the term used to describe a compound that speeds up chemical reactions without being consumed: a world full of questions lies behind this simple term. Nearly all reactions that occur in living cells require catalysts and without them, life would be impossible, but what is the mechanism by which they work? What kind of catalysts are suitable to produce the desired products with high efficiency under mild conditions? How do they direct the reaction to a pathway which requires less activation energy? Many research groups attempt to discover the unknown aspects of the catalyst world.
    [Show full text]