Asymmetric Synthesis Quinoxp* Ligands

Total Page:16

File Type:pdf, Size:1020Kb

Asymmetric Synthesis Quinoxp* Ligands 2006 VOLUME 6 NUMBER 10 Asymmetric Synthesis QUINOXP* LIGANDS CARREIRA DOLEFIN LIGANDS VAULTED BIARYL LIGANDS AND BINOL DERIVATIVES OXAZOLIDINETHIONE AND THIAZOLIDINETHIONE AUXILIARIES GLEASON CHIRAL AUXILIARY SHI EPOXIDATION DIKETAL CATALYST SHVO’S CATALYST (7R,10S)-(+)-1-Aza-10-isopropyl-8-oxa-4-thiabicyclo(5,3,0)-2-decanone chiral lactam auxiliary capable of forming chiral quaternary centers sigma-aldrich.com Introduction Vol. 6 No. 10 Asymmetric synthesis remains a challenge to synthetic chemists as the demand for enantiomerically pure compounds continues to increase. Many scientists working in Aldrich Chemical Co., Inc. chemical synthesis and drug discovery are striving to find new methods for asymmetric Sigma-Aldrich Corporation synthesis that would lead to the development of new and exciting chiral auxiliaries. In 6000 N. Teutonia Ave. addition, asymmetric catalysis is exploding, as new methods for obtaining enantiomerically Milwaukee, WI 53209, USA pure compounds has fueled a rapidly growing field in chemical synthesis. This edition of ChemFiles describes the applications of new chiral ligands and auxiliaries for use in asymmetric synthesis. Sigma-Aldrich is proud to carry over 5,000 chiral products To Place Orders for the successful construction of complex asymmetric architectures. In most cases, the Telephone 800-325-3010 (USA) cutting-edge methodologies illustrated herein exhibit exceptional levels of stereoselectivity. FAX 800-325-5052 (USA) Introduction For a complete listing of products related to asymmetric synthesis, please visit us at sigma-aldrich.com/asymmetric. Customer & Technical Services At Sigma-Aldrich™, we are committed to being your preferred supplier for all of your research needs. If you are unable to find a product for your research in asymmetric Customer Inquiries 800-325-3010 synthesis, we welcome your input. “Please Bother Us” with your suggestions and contact Technical Service 800-231-8327 your local Sigma-Aldrich office. SAFC™ 800-244-1173 Custom Synthesis 800-244-1173 Flavors & Fragrances 800-227-4563 International 414-438-3850 Coming Soon! 24-Hour Emergency 414-438-3850 Web Site sigma-aldrich.com The NEW 2007–2008 Email [email protected] Aldrich Handbook of Fine Chemicals ...featuring over 35,000 listings including 2,000 new products. Subscriptions To request your FREE subscription to ChemFiles, please contact us by: Phone: 800-325-3010 (USA) Order your FREE copy today! Mail: Attn: Marketing Communications (Shipping January 2007) Aldrich Chemical Co., Inc. Sigma-Aldrich Corporation 35,000 Chemical Listings P.O. Box 355 Milwaukee, WI 53201-9358 10,000 Structures Email: [email protected] 2,000 NEW Products 6,100 Citations International customers, please contact your 3,000 Application Notes local Sigma-Aldrich office. For worldwide contact Enhanced Application information, please see back cover. Index ChemFiles are also available in PDF format on the Advanced Product Tables Internet at sigma-aldrich.com/chemfiles. Aldrich brand products are sold through Sigma- Aldrich, Inc. Sigma-Aldrich, Inc. warrants that its products conform to the information contained in this and other Sigma-Aldrich publications. Purchaser must determine the suitability of the Call 1-800-325-3010 (USA) to reserve your copy or visit product for its particular use. See reverse side of sigma-aldrich.com/handbook16 today! invoice or packing slip for additional terms and conditions of sale. All prices are subject to change without notice. About Our Cover ChemFiles is a publication of Aldrich Chemical The cover graphic depicts the structure of the Gleason Chiral Auxiliary, (7R,10S)-(+)-1-aza- Co., Inc. Aldrich is a member of the Sigma-Aldrich 10-isopropyl-8-oxa-4-thiabicyclo[5.3.0]-2-decanone. This chiral lactam auxiliary has been Group. © 2006 Sigma-Aldrich Co. successfully employed in the stereocontrolled synthesis of all carbon quaternary centers. The unique methodology developed by Gleason allows for the creation of either antipode of the product using a single isomer of the auxiliary. sigma-aldrich.com 3 QuinoxP* Ligands t-Bu Me Various optically active phosphine ligands incorporating a chiral N P center at phosphorus display exceptional enantiosectivities in QuinoxP* 1 metal-catalyzed asymmetric synthesis. For instance, known N P classes of P-chiral phosphine ligands offer good to excellent NHAc NHAc 2 Me t-Bu 2 2 1 R * R enantiocontrol in Ru- and Rh-catalyzed hydrogenation reactions. R R1 [Rh(nbd)2]BF4 (1 mol %) The one limitation associated with these ligands is their sensitivity R3 R3 H2 (3 atm), MeOH, 6 h to air, which has impeded widespread applicability in bench-top chemistry. Imamoto and co-workers have addressed this deficiency Scheme 1 QuinoxP* Ligands through the development of QuinoxP*, which is based on an 3 electron-withdrawing quinoxaline architecture. Entry R1 R2 R3 ee (%) (config) Sigma-Aldrich is pleased to offer both enantiomers of QuinoxP* a 1 CO2Me Ph H 99.9 (R) for the research market.† The reactivity profile of these innovative, chiral ligands is covered below and highlights the impressive 2 CO2Me 4-AcO-3-MeOC6H3 H 99.6 (R) breadth of valuable transformations mediated by QuinoxP*. These 3 Me H CO2Me 99.7 (R) powerfully efficient ligands exhibit high levels of enantiocontrol 4 Me CO Me H 99.2 (R) in synthetic transformations ranging from metal-catalyzed 2 asymmetric 1,4-additions of arylboronic acids to enantioselective 5 Ph H H 99.9 (R) 3 alkylative ring opening to asymmetric hydrogenations. It is 6 1-adamantyl H H 96.3 (S) worth noting that QuinoxP* is not oxidized at the stereogenic a The reaction was completed within 1 h. phosphorus center on standing at ambient temperature in air for more than 9 months. Table 1 Imamoto has also gone to great lengths to develop t-Bu Me enantiomerically pure P-chiral ligands for industrially useful N P transformations such as asymmetric hydrogenation. Impressively, 3 mol % a diverse array of prochiral amino acid and amine substrates were N P hydrogenated with great efficiency to yield highly enantiopure Me t-Bu amine derivatives (Scheme 1). These experiments were carried [RhCl(C2H4)2]2 (3 mol %) O Ph O out at room temperature in methanol under low pressures of PhB(OH)2, KOH, dioxane/H2O, 1 h hydrogen (3 atm). All hydrogenation reactions were complete 97%, 99% ee in 6 hours and with enantiomeric excesses ranging from 96 to 99.9%. Dramatic stereochemical reversal, consistent with the Scheme 2 results observed with the related (S,S)-tert-Bu-BisP* ligands,4,5 was obtained when 1-acetylamino-1-adamantylethene was t-Bu Me hydrogenated to afford the S-configuration amine with >96% N P enantioselectivity (Table 1). 5 mol % O Imamoto and co-workers have also exploited the high activity N P OH rder: 1.800.325.3010 R1 1 2 Me t-Bu R R of the QuinoxP* ligand in rhodium-catalyzed enantioselective O 2 1 PdCl (cod) (5 mol %), R Zn, CH Cl , rt 1,4-additions of arylboronic acids to a,b-unsaturated carbonyl R 2 2 2 2 R1 substrates.3 High yields of the addition products were obtained by running the reactions between 40 and 50 ºC (Scheme ). The exceptional enantiocontrol exerted by this Rh(I)-catalyzed system is Scheme 3 evident in the robust performance when compared to the use of BINAP as the chiral ligand.6 Entry R1 R2 Time (h) Yield (%)a ee (%) (config) Additionally, Imamoto and co-workers have succeeded in developing a Pd-catalyzed C–C bond-forming reaction, which 1 H Me 2 90 95.6 (1S,2S) displays high enantioselectivities with both dimethyl- and 2 H Et 15 88 97.6 (1S,2S) diethylzinc (Scheme 3, Table ). This alkylative ring-opening 3 F Me 2 90 93.8 (1S,2S) methodology benefits from simply premixing PdCl2(cod) and QuinoxP* for 2 hours at room temperature, leading to a highly a Isolated yield. T e c h n i c a l active catalyst. This catalyst system affords excellent yields of Table 2 the ring-opened products and selectivities that rival the highest reported for this transformation. These results, when combined with the outstanding methodologies presented above, indicate that QuinoxP* is broadly useful for a variety of asymmetric 3 metal-catalyzed transformations. S ervice: 1.800.231.8327 (R,R)-,3-Bis(tert-butylmethylphosphino)quinoxaline 8 (S,S)-,3-Bis(tert-butylmethylphosphino)quinoxaline 8 C18H28N2P2 C18H28N2P2 t-Bu t-Bu FW: 334.38 Me FW: 334.38 Me N P N P N P N P Me t-Bu t-Bu Me 676403-100MG 100 mg 676411-100MG 100 mg 676403-500MG 500 mg 676411-500MG 500 mg Ready to scale up? For competitive quotes on larger quantities or custom synthesis, contact SAFC™ at 1-800-44-1173 (USA), or visit www.safcglobal.com. 4 m-Dichlorotetraethylene dirhodium(I) 8 Dichloro(1,5-cyclooctadiene)palladium(II) C8H16Cl2Rh2 C8H12Cl2Pd CH2 H2C Cl Cl FW: 388.93 H2C CH2 FW: 285.51 Rh Rh Pd [12081-16-2] H2C Cl CH2 [12107-56-1] Cl CH2 H2C 275891-250MG 250 mg 656763-100MG 100 mg 275891-1G 1 g 656763-1G 1 g Carreira DOLEFIN Ligands H CO For the past years, the Carreira group has been employing 3 CH3 chiral [2.2.2]bicyclooctadienes derived from (R)- or (S)-carvone in Ir(I)-catalyzed kinetic resolution of allylic carbonates7 and Rh(I)-catalyzed conjugate addition reactions of boronic acids.8 H3C More recently, Carreira has developed the ligand 1 (Figure 1), 1 which exhibited substantially improved enantioselectivity in the Figure 1 1,4-addition of arylboronic acids to a,b-unsaturated carbonyls.9 This new ligand facilitates selective preparations of diarylmethine stereogenic centers, even when there is little differentiation 2 1.5 mol % X between the two aryl groups. Heretofore, the stereoselective [Rh(C2H4)2Cl2]2 O 3.3 mol % 1 synthesis of this motif had been a challenge, with rather limited B(OH) 2 0.5 eq KOH O methods for its preparation.10 Ot-Bu + 2 MeOH/H O (10:1) Ot-Bu X1 X 2 50 °C In one report, tert-butyl cinnamate was converted to (S)-tert-butyl X1 3-(4-methoxyphenyl)-3-phenylpropanoate in the presence of the X1 = H, X2 = OMe 85%, 93% ee Carreira Carreira DOLEFIN Ligands Rh(I)-1 complex in excellent yield and selectivity.
Recommended publications
  • Organic Synthesis: Handout 1
    Prof Tim Donohoe: Strategies and Taccs in Organic Synthesis: Handout 1 Organic Synthesis III 8 x 1hr Lectures: Michaelmas Term Weeks 5-8 2016 Mon at 10am; Wed at 9am Dyson Perrins lecture theatre Copies of this handout will be available at hEp://donohoe.chem.ox.ac.uk/page16/index.html 1/33 Prof Tim Donohoe: Strategies and Taccs in Organic Synthesis: Handout 1 Organic Synthesis III Synopsis 1) Introduc5on to synthesis: (i) Why do we want to synthesise molecules- what sort of molecules do we need to make? (ii) What aspects of selecvity do we need to accomplish a good synthesis (chemo-, regio- and stereoselecvity)? (iii) Protecng group chemistry is central to any syntheAc effort (examples and principles) (iv) What is the perfect synthesis (performed in industry versus academia)? 2) The chiral pool: where does absolute stereochemistry come from? 3) Retrosynthesis- learning to think backwards (revision from first and second year). Importance of making C-C bonds and controlling oxidaAon state. Umpolung 4) Some problems to think about 5) Examples of retrosynthesis/synthesis in ac5on. 6) Ten handy hints for retrosynthesis 7) Soluons to the problems Recommended books: General: Organic Chemistry (Warren et al) Organic Synthesis: The DisconnecRon Approach (S. Warren) Classics in Total Synthesis Volumes I and II (K. C. Nicolaou) The Logic of Chemical Synthesis (E. J. Corey) 2/33 View Article Online / Journal Homepage / Table of Contents for this issue 619461 Strychniqae and BYucine. Pavt XLII. 903 Prof Tim Donohoe: Strategies and Taccs in Organic Synthesis: Handout 1 (i) Why do we want to synthesise complex molecules? Isolated from the Pacific Yew in 1962 Prescribed for prostate, breast and ovarian cancer Unique mode of acRon 1x 100 year old tree = 300 mg Taxol Isolated in 1818- poisonous Stuctural elucidaon took R.
    [Show full text]
  • Chemical Synthesis of Carbon-14 Labeled Ricinine and Biosynthesis
    1.2 PROC. OF 'nJE OKLA. ACAD. OF SCI. FOR 19M Chemical Synthesis of Carbon-14 Labeled Ridnine and Biosynthesis of Ricinine in Ricinus communis L I IL s. YANG, B. TRIPLE'rJ', IL S. )[LOS and G. B. WALLER Oldahoma State Umvenity, Acricultural Experiment station, Stillwater Ricinine (Fig. 1, tormula V; 1,2-dihydro-4-methoxy-1-methyl-2-oxo­ ntcotinonttrUe) is a mildly toxic alkaloid produced by the castor plant Bkiflu.t commuflu L. Studies on the biosynthesis of ricinine have been in progreu in our laboratory for several years (Waller and Henderson, 1961; Hadwiger et a!., 1963; Yang and Waller, 1965). Recently Waller et at (1Na) demoll8trated that 7~% to 90% of ricinine-'H and ricinine-8-t 'C wu degraded by the caator plant. This demonstration of metabolic acti­ vity servea to refute the earlier concepts that regarded alkaloids as by­ products of a number of irreversible and useless reactions associated with nitrogen metabolism (Pictet and Court, 1907; Cromwell, 1937; Vickery, 1941 ). To enable us to further stUdy the degradation of ricinine by the cutor plant, alkaloid labeled with carbon-14 in the pyridine ring which poueues a high specific activity is required. This report provides detailed information on the micro-scale synthesis of ricinine-3,~14C. The chemical synthesis of ricinine was initiated in the early part of this century by several workers in their attempts to prove the structure of the akaIoid. Spilth and Koller (1923) synthesized ricinine by the oxidation of 4-chloroquinoline via the intermediates 4-chloro-2-aminoquin­ oline-3-carboxylic acid and 2,4-dichlorontcoUnonitrile.
    [Show full text]
  • Page 1 of 108 RSC Advances
    RSC Advances This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. This Accepted Manuscript will be replaced by the edited, formatted and paginated article as soon as this is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/advances Page 1 of 108 RSC Advances Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis Majid M. Heravi,* Vahideh Zadsirjan, Behnaz Farajpour Department of Chemistry, School of Science, Alzahra University, Vanak, Tehran, Iran Email: [email protected] Abstract Various chiral oxazolidinones (Evans' oxazolidinones) have been employed as effective chiral auxiliaries in the asymmetric alkylation of different enolates. This strategy has been found promising and successful when used as key step (steps) in the total synthesis of several biologically active natural products. In this report, we try to underscore the applications of Manuscript oxazolidinones as chiral auxiliary in asymmetric alkylation, and particularly in crucial chiral inducing steps in the total synthesis of natural products, showing biological activities.
    [Show full text]
  • 1,2-Asymmetric Induction in Carbonyl Compounds - a Computational Study
    1,2-Asymmetric Induction in Carbonyl Compounds - A Computational Study by Jeffrey Retallick B.Sc., University of New Brunswick, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science In the Graduate Academic Unit of Chemistry Supervisor(s): Ghislain Deslongchamps, Ph.D., Chemistry Examining Board: Rodney Cooper, M.Sc., Computer Science, Chair External Examiner: Ben Newling, Ph.D., Physics This thesis is accepted by the Dean of Graduate Studies THE UNIVERSITY OF NEW BRUNSWICK October, 2019 © Jeffrey Retallick, 2020 Abstract In asymmetric synthesis, it is important to reliably predict the major stereoisomeric prod- uct of a reaction. One such reaction is the nucleophilic addition to a carbonyl compound featuring an adjacent chiral carbon. Several reaction models exist in literature to predict the facial selectivity of these reactions. These models provide simple visual drawings to quickly predict the major product of such a reaction without requiring exhaustive quantum mechanical calculations. These models are used on a daily basis, and some models per- form better than others, making it valuable to investigate which ones are the most effective. For the first time in this thesis, high-level computations have been performed on all of the literature models to verify their efficacy. The results of this thesis offers a definitive answer that the Felkin-Anh and Wintner models are the most effective, and that bent bond theory offers an interesting insight on the mechanics of these reactions. ii Dedication Kyle, Nan, and Taryn. iii Acknowledgements Thanks to my family for their support. Ghislain, thank you for putting up with me over the past while.
    [Show full text]
  • Chapter 8. Chiral Catalysts José M
    Chapter 8. Chiral Catalysts José M. Fraile, José I. García, José A. Mayoral 1. The Origin of Enantioselectivity in Catalytic Processes: the Nanoscale of Enantioselective Catalysis. Enantiomerically pure compounds are extremely important in fields such as medicine and pharmacy, nutrition, or materials with optical properties. Among the different methods to obtain enantiomerically pure compounds, asymmetric catalysis1 is probably the most interesting and challenging, in fact one single molecule of chiral catalyst can transfer its chiral information to thousands or even millions of new chiral molecules. Enantioselective reactions are the result of the competition between different possible diastereomeric reaction pathways, through diastereomeric transition states, when the prochiral substrate complexed to the chiral catalyst reacts with the corresponding reagent. The efficiency of the chirality transfer, measured as enantiomeric excess [% ee = (R−S)/(R+S) × 100], depends on electronic and steric factors in a very subtle form. A simple calculation shows that differences in energy of only 2 kcal/mol between these transition states are enough to obtain more than 90% ee, and small changes in any of the participants in the catalytic process can modify significantly this difference in energy. Those modifications may occur in the near environment of the catalytic centre, at less than 1 nm scale, but also at longer distances in the catalyst, substrate, reagent, solvent, or support in the case of immobilized catalysts. This is the reason because asymmetric
    [Show full text]
  • Synthesis and Biosynthesis of Polyketide Natural Products
    Syracuse University SURFACE Chemistry - Dissertations College of Arts and Sciences 12-2011 Synthesis and Biosynthesis of Polyketide Natural Products Atahualpa Pinto Syracuse University Follow this and additional works at: https://surface.syr.edu/che_etd Part of the Chemistry Commons Recommended Citation Pinto, Atahualpa, "Synthesis and Biosynthesis of Polyketide Natural Products" (2011). Chemistry - Dissertations. 181. https://surface.syr.edu/che_etd/181 This Dissertation is brought to you for free and open access by the College of Arts and Sciences at SURFACE. It has been accepted for inclusion in Chemistry - Dissertations by an authorized administrator of SURFACE. For more information, please contact [email protected]. Abstract Traditionally separate disciplines of a large and broad chemical spectrum, synthetic organic chemistry and biochemistry have found in the last two decades a fertile common ground in the area pertaining to the biosynthesis of natural products. Both disciplines remain indispensable in providing unique solutions on numerous questions populating the field. Our contributions to this interdisciplinary pursuit have been confined to the biosynthesis of polyketides, a therapeutically and structurally diverse class of natural products, where we employed both synthetic chemistry and biochemical techniques to validate complex metabolic processes. One such example pertained to the uncertainty surrounding the regiochemistry of dehydration and cyclization in the biosynthetic pathway of the marine polyketide spiculoic acid A. The molecule's key intramolecular cyclization was proposed to occur through a linear chain containing an abnormally dehydrated polyene system. We synthesized a putative advanced polyketide intermediate and tested its viability to undergo a mild chemical transformation to spiculoic acid A. In addition, we applied a synthetic and biochemical approach to elucidate the biosynthetic details of thioesterase-catalyzed macrocyclizations in polyketide natural products.
    [Show full text]
  • Highly Enantioselective Synthesis of Γ-, Δ-, and E-Chiral 1-Alkanols Via Zr-Catalyzed Asymmetric Carboalumination of Alkenes (ZACA)–Cu- Or Pd-Catalyzed Cross-Coupling
    Highly enantioselective synthesis of γ-, δ-, and e-chiral 1-alkanols via Zr-catalyzed asymmetric carboalumination of alkenes (ZACA)–Cu- or Pd-catalyzed cross-coupling Shiqing Xu, Akimichi Oda, Hirofumi Kamada, and Ei-ichi Negishi1 Department of Chemistry, Purdue University, West Lafayette, IN 47907 Edited by Chi-Huey Wong, Academia Sinica, Taipei, Taiwan, and approved May 2, 2014 (received for review January 21, 2014) Despite recent advances of asymmetric synthesis, the preparation shown in Schemes 1 and 2 illustrate the versatility of ZACA of enantiomerically pure (≥99% ee) compounds remains a chal- represented by the organoaluminum functionality of the ini- lenge in modern organic chemistry. We report here a strategy tially formed ZACA products. Introduction of the OH group for a highly enantioselective (≥99% ee) and catalytic synthesis by oxidation of initially formed alkylalane intermediates in of various γ- and more-remotely chiral alcohols from terminal Scheme 2 is based on two considerations: (i) the proximity of the alkenes via Zr-catalyzed asymmetric carboalumination of alkenes OH group to a stereogenic carbon center is highly desirable for (ZACA reaction)–Cu- or Pd-catalyzed cross-coupling. ZACA–in situ lipase-catalyzed acetylation to provide ultrapure (≥99% ee) di- oxidation of tert-butyldimethylsilyl (TBS)-protected ω-alkene-1-ols functional intermediates, and (ii) the versatile OH group can R S α ω produced both ( )- and ( )- , -dioxyfunctional intermediates (3) be further transformed to a wide range of carbon groups by – ee ≥ ee in 80 88% , which were readily purified to the 99% level tosylation or iodination followed by Cu- or Pd-catalyzed cross- by lipase-catalyzed acetylation through exploitation of their high α ω coupling.
    [Show full text]
  • Kem-4.450 Asymmetric Synthesis
    KemKem--4.4504.450 AsymmetricAsymmetric SynthesisSynthesis Prof. Ari Koskinen Laboratory of Organic Chemistry © Helsinki University of Technology, Laboratory of Organic Chemistry © Ari Koskinen, 2007 ChiralityChirality andand DifferingDiffering PropertiesProperties OO Carvone spearmint odor caraway NH NH 2 H 2 H Aspartame HO2C NCO2Me HO2C NCO2Me (Nutrasweet) O O sweet bitter O O Thalidomide N N O O OON OON H H sedative, hypnotic teratogenic © Helsinki University of Technology, Laboratory of Organic Chemistry © Ari Koskinen, 2007 PharmaceuticalsPharmaceuticals Growing need for enantiopure compounds Enantiomers/diastereomers may have adverse effects Diastereomers usually easier to separate Enantiomers: FDA required © Helsinki University of Technology, Laboratory of Organic Chemistry © Ari Koskinen, 2007 PharmaceuticalsPharmaceuticals Penicillamine: NH2 NH2 CO2H CO2H SH SH antidote for Pb, Au, Hg can cause optic atrophy => blindness Timolol: O OH O OH H H N O N N O N N N N N S S adrenergic blocker ineffective © Helsinki University of Technology, Laboratory of Organic Chemistry © Ari Koskinen, 2007 SalesSales ofof EnantiomericEnantiomeric DrugsDrugs andand IntermediatesIntermediates Chem. Eng. News 2001, 79 (40), 79-97. © Helsinki University of Technology, Laboratory of Organic Chemistry © Ari Koskinen, 2007 AsymmetricAsymmetric InductionInduction -- DefinitionsDefinitions Chirality - handedness Asymmetry - lacking all symmetry (except E) B Dissymmetry - lacking some element of symmery H NB!!! Molecules can be chiral but not asymmetric!
    [Show full text]
  • Catalytic Asymmetric Synthesis
    Catalytic Asymmetric Synthesis Dr Alan Armstrong Rm 313 (RCS1), ext. 45876; [email protected] 7 lectures Recommended texts: “Catalytic Asymmetric Synthesis, 2nd edition”, ed. I Ojima, Wiley-VCH, 2000 (or 1st ed., 1993, which contains most of the lecture material) “Asymmetric Synthesis”, G Procter, Oxford, 1996 Aims of course: To give students an understanding of the basic principles of asymmetric catalysis, and to demonstrate these in the context of state-of-the-art catalytic asymmetric processes for C-C bond formation and redox processes. Course objectives: At the end of this course you should be able to: • Recognise the types of functional groups which can be prepared by catalytic asymmetric methods discussed in the course; • Use this knowledge in planning the synthesis of enantiomerically enriched compounds from given prochiral starting materials; • Outline the scope and limitations of any methods you propose, with respect to parameters such as turnover, substrate and functional group tolerance, availability of catalysts and/or ligands etc Course content (by lecture, approximately): 1. Introduction and general principles of asymmetric catalysis. Oxidation of functionalised olefins: asymmetric epoxidation of allylic alcohols and enones 2. Oxidation of unfunctionalised olefins: epoxidation, dihydroxylation and aminohydroxylation. 3. Reduction of olefins: asymmetric hydrogenation. 4. Reduction of ketones and imines 5. Asymmetric C-C bond formation: nucleophilic attack on carbonyls, imines and enones 6. Asymmetric transition metal catalysis in C-C bond forming reactions (cross-couplings, Heck reactions, allylic substitution, carbenoid reactions) 7. Chiral Lewis acid catalysis (aldol reactions, cycloadditions, Mannich reactions, allylations) 1 Catalytic Asymmetric Synthesis - Lecture 1 Background and general principles • Why asymmetric synthesis? The need to prepare pharmaceuticals and other fine chemicals as single enantiomers drives the field of asymmetric synthesis.
    [Show full text]
  • Automated Injection from EWOD Digital Microfluidic Chip Into HPLC Purification System G.J
    Automated injection from EWOD digital microfluidic chip into HPLC purification system G.J. Shah1,2, J. Lei1, S. Chen1, C.-J. Kim1, P.Y. Keng1, R.M. van Dam1 1University of California, Los Angeles, CA 90095, 2Sofie Biosciences, Culver City, CA 90230, USA ABSTRACT We report an automated “chip-to-world” interface between an electrowetting-on-dielectric (EWOD) digital microfluidic device and high-performance liquid chromatography (HPLC) system, expanding the application of EWOD chemical synthesis devices to syntheses that require HPLC purification. The interface collects the crude product from the chip without the need for chip disassembly or other manual intervention. We report (a) bubble-free filling of the injection loop; (b) quantification of how much crude product from the chip is loaded into the loop; and (c) successful injection and HPLC purification of a crude product. It should be noted that because of the small chip volume, analytical-scale HPLC could be used, typically leading to 10-20x more concentrated purified product than semi-preparative HPLC. KEYWORDS Digital microfluidics, Electrowetting on dielectric (EWOD), world-to-chip interface, High-performance liquid chromatography (HPLC), Purification INTRODUCTION Due to its well-controlled volumes, inert surfaces, all-electronic control and flexibility of fluid movement, there has been growing interest in digital microfluidics using electrowetting-on-dielectric (EWOD) for chemical, biochemical and radiochemical synthesis applications [1,5,6]. Several of these require post-synthesis purification, separation and/or analysis. High-performance liquid chromatography (HPLC) is an important and ubiquitous separation technique for both preparative and analytical systems [7]. However, products are often manually pipetted off the chip and introduced into the HPLC [1].
    [Show full text]
  • Simulation and Evaluation of Chemical Synthesis—SECS: an Application of Artificial Intelligence Techniques
    ARTIFICIAL INTELLIGENCE 173 " t Simulation and Evaluation of Chemical Synthesis—SECS: An Application of Artificial Intelligence Techniques W. Todd Wipke, Glenn I. Ouchi, and S. Krishnan Board ofStudies in Chemistry, University of California, Santa Cruz, CA 95064, U.S.A. Recommended by N. S. Sridharan ABSTRACT 77ii?problem of designing chemicalsyntheses ofcomplex organic compounds is achallenging domain for application of artificial intelligence techniques. SECS is an interactive program to assist a chemist in heuristically searching and evaluating the space ofgood syntheticpathways. The chemist- computer team, linked through computer graphics, developssynthetic plans using a logic-centered backwardanalysisfrom the target structure. The reaction knowledge base, written in the ALCHEM language, is separatefrom the program and control strategies. Performance is demonstratedon the insectpheromone grandisol. 1. Introduction OrganicSynthesisis of premier importance in producing new chemical compounds for use as drugs, fuels, plastics, dyes, superconductors, and a whole host of other materials. Thus, there is great interest in being able to design good efficient syn- an organic synthesis requires ready i theses of chemical compounds. The design of knowledge of many reactions, chemical principles, and specific facts. Over 250,000 appearannually in the chemical literature reporting new facts and «-» chemical papers *f principles and according to Chemical Abstracts, thechemical literature is increasing at 8.5% per year compounded. Over 4,000,000 different chemical compounds have been reported in the literature. As in all fields of science it is virtually impossible for a single person to keep track ofall the developments taking place, even in this seemingly narrow field of specialization. Clearly it would seem beneficial to have a computer help the chemist digest the available information, and evaluate, correlate, and extrapolate it to provide ideas for new experiments for advancement of knowledge in this field and for solving important synthetic problems.
    [Show full text]
  • Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules Within Constrained Environments
    Materials 2011, 4, 183-205; doi:10.3390/ma4010183 OPEN ACCESS materials ISSN 1996-1944 www.mdpi.com/journal/materials Review Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments Yasuhiro Ishida 1,2,3,* 1 RIKEN, Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan 2 PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan 3 Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +81-48-462-1111 (ext. 6351); Fax: +81-48-467-8214. Received: 29 November 2010; in revised form: 4 January 2010 / Accepted: 5 January 2010 / Published: 11 January 2011 Abstract: In liquid crystals (LCs), molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available.
    [Show full text]