The Total Synthesis of Strychnine

Total Page:16

File Type:pdf, Size:1020Kb

The Total Synthesis of Strychnine GENERAL ¨ ARTICLE The Total Synthesis of Strychnine Edited by Setty Mallikarjuna Babu and Subramania Ranganathan The enormous reach of R B H N Woodward in the design and H synthesis of carbon constel- N lationsisfurtherexempli- H H fied with the total synthesis O O H ofstrychnine(p.641),which even when viewed from the Either we make Strychnine or take Strychnine. vantage of ensuing signifi- – R B Woodward cant developments in or- ganic synthesis is an amaz- ing feat! This is followed by Strychnine! No other molecule has captured the popular imagina- the total synthesis of chlo- tion as strychnine, perhaps because thousands of writers of fiction rophyll (p.645), where RB have used it to dispatch the recipient and then several have made pledged the entire efforts on thrillers using ingenious deduction to catch the perpetrator! Known an untested porphyrin to since the 16th century from the forests including the Coramandal purpurin change, an essen- Coast of India, it was isolated in a pure form in 1818 and the tialtransformation toachieve structure established in 1947! Unlike the 181 atoms scattered in the total synthesis. The third space as in vitamin B , strychnine, having six asymmetric centres additional example is the to- 12 tal synthesis of cepha- and 7 rings is packed with a mere 24 skeleton atoms! losporin C (p.649), The 2-Veratryl indole (1) readily prepared by Fischer indole synthesis Nobel Lecture delivered by from acetoveratrone was transformed to tryptamine 3,whose RB, above all, reflects the fact that in all these cre- Schiff’s base with CHOCOOEt underwent smooth cyclization ations, he identified an an- with TsCl/Py to generate the spiro ring-V, 4 which was trans- chor from which he never formed to 5. Ozonolysis followed by treatment with MeOH/HCl wavered – in this case the generated the critical pyridone 6 (ring-III) (Scheme 1). Initial simple molecule cysteine. efforts to effect a Dieckman condensation of the two ester groups were thwarted by the highly electrophilic Ts group present, forming in preference, the Sciff’s base. The Ts group was removed(HI,redP)andreplacedbyAc(Ac2O, Py), esterified (CH2N2). The resulting 7 underwent smooth Dieckman condensa- tion to give 8, generating ring-IV. Keywords Strychnine. RESONANCE ¨ July 2014 641 GENERAL ¨ ARTICLE + - CH2NMe3 I I NH2 CHO OMe 1. CH O, Me NH 1. NaCN, DMF N 2 2 OMe N OMe CO2Et H N H 2. MeI H 2. LAH OMe OMe OMe 1 2 3 Ts-Cl N V CO2Et V N Ts N Ts N OMe TsCl, Py CO2Et NaBH4 Ac2O, Py OMe CO2Et N N OMe H H B: OMe OMe OMe 4 N Ts N Ts N Ts CO Et CO2Et HI, red P CO2Et O , AcOH 2 MeOH, HCl CH CO Me OMe 3 N N 2 2 N CO2Me III Ac Ac CO2Me O OMe 6 5 Scheme 1. The enol ester group in 8 was transformed to acrylate 9 and then subjected to reduction. This process creates another chiral centre where the major product turned out to be unwanted E-ester which was readily epimerised to the more stable D-acid, 10.The structure of compound 10 was conformed from a sample secured from natural strychnine. For this purpose 10 was readily resolved using quinidine and esterified to the methyl ester corresponding to 10 which was identical to that obtained from the natural sources. This enabled further transformations with the more readily ob- tained material from the natural sources. The linking of the D- carboxyl group in 10 to the nitrogen that would generate ring-VI necessitated the inversion of this centre; this was achieved in an unusual manner by treatment of 10 with Ac2O and pyridineto form the enol acetate 11 (Scheme 2). The formation of 11 could be rationalized by the initially formed anhydride, that undergoes nucleophilic acyl transfer, decarboxyla- tion and acylation of the thus generated enolate! Vigorous acid hydrolysis of 11 afforded 12 (Scheme 3). The protanation of the enolate takes place from the E-side. Thus 12 is not disposed for linking with the trans-NH. Woodward did not consider this as an impediment because of the ready epimerisation of this centre. 642 RESONANCE ¨July 2014 GENERAL ¨ ARTICLE H N H N Ac N Ac CO H IV 2 1. AC2O,Py CO2Me OH TsCl, Py N CH2CO2H CH2CO2Me NaOMe, MeOH N N CO2Me 2. CH2N2 O O O 7 8 H H H N Ac N Ac N Ac De activated OTs PhCH SNa SCH Ph H ,Pd-C N 2 N 2 Ra ney Ni N 2 CO2Me CO2Me CO2Me O O O 9 H H H N Ac N Ac N Ac [OH- ] N N N AC2O,Py Me aq HCl, AcOH CO2Me CO2H OAc O O O 10 11 H H N H N N Ac VI O O 8 Se O ,EtOH N O N 1.HC CNa, THF N 2 13 Me O O H 2. H2 , Lindlar catalyst O O 12 O 12 13 H N H O O N N HO LAH AlZ O H N + R N H N 1.HBr, AcOH, 120 O HC CH2 XO HC HO 2. aq H2SO4 CH2 O 14 15 H H N N H H N KOH, EtOH N H H H O O H O 16 17 OH Isostrychnine I Strychnine Scheme 2 (top). Scheme 3 (bottom). RESONANCE ¨ July 2014 643 GENERAL ¨ ARTICLE Indeed this turned out to be true! Treatment of 12 with SeO2-EtOH gave 13 with the generation of ring-VI. The 3D representation of 13 clearly shows that the epimerization has indeed taken place! The pathway to strychnine now involves addition of two carbon atoms and creation of chiral centres at 8, 13 and 12 positions (12) (Scheme 3). At this stage compound 13 is highly concave and the carbon at 8 rests at the bottom of it. To deliver an H to this carbon is the kind of challenge that Nature often posed and Woodward overcame this using an Al-courier! Compound 13 was treated with sodium acetylide in THF and the acetylinic moiety was reduced to provide 14. Compound 14 when reacted with LAH in refluxing ether effected the reduction of the amide present in ring-VI and delivered the hydrogen to the most inaccessible carbon-8 to form 15. Compound 15 is related to isostrychnine 16 where the allyl alcohol is isomerised to provide a hydroxy methyl isomer. This transformation proved exceptionally difficult. Eventually, treat- ment of 15 with HBr/AcOH at 120oC, and the resulting mixture of halo compounds on hydrolysis in boiling aq. H2SO4 generated the desired 16, isostrychnine! The action of ethanolic KOH led to the closure of the 7-memberd oxide ring-VII, which also generated the chiral centre at 12 and 13 in a correct order. Even in the light of significant developments in organic synthesis during the intervening six decades, Woodward’s synthesis of strychnine defies the imagination of chemists! Here again Wood- ward had to overcome the problems raised by Nature in placing one of the Hs inside the bowl with 4 outside! Suggested Reading [1] R B Woodward, M P Cava, W D Ollis, A Hunger, H U Daeniker and K Schenker, Tetrahedron, Vol.19, p.247, 1963. 644 RESONANCE ¨July 2014.
Recommended publications
  • Ochem ACS Review 18 Enols and Enolates
    ACS Review Enols and Enolates 1. Which of the following have an enol form? I. benzaldehyde, C 6H5CHO II. 2,2-dimethylpropanal, (CH 3)3CCHO III. 2-chloropropanal, CH 3CHClCHO A. only I B. only II C. only III D. all of them have an enol form 2. Which one of the following has two different enol forms? A. cyclohexanone B. 2,2-dimethylcyclohexanone C. 3,3-dimethylcyclohexanone D. 4,4-dimethylcyclohexanone 3. How many alpha hydrogens are there on 2,4-dimethyl-3-pentanone? A. two B. three C. four D. six 4. Identify the most acid hydrogen for the following compound. A. 1 B. 2 C. 3 D. 4 5. What is the product of the reaction below? A. A B. B C. C D. D 6. Arrange the following compounds in order of decreasing acidity. A. I > II > III B. II > III > I C. III > II > I D. III > I > II 7. Identify the keto form of the following enol. A. 1-penten-3-one B. (E)-3-penten-2-one C. 2-pentanone D. (E)-3-pentenal 8. What is the relationship between keto and enol tautomers? A. resonance forms B. stereoisomers C. constitutional isomers D. different conformations of the same compound 9. Which of the following has the highest percentage of enol in a keto-enol equilibrium? A. hexanal B. 2-hexanone C. 2,4-hexanedione D. 2,5-hexanedione 10. Which one of the following optically active compounds racemizes in dilute KOH/CH 3OH solution? A. A B. B C. C D. D 11.
    [Show full text]
  • Linear Form of Glucose
    Linear Form Of Glucose How gymnorhinal is Obadias when morning and daring Stirling diabolizing some rappels? Forest is plenteously sachemic after contemplative Raymundo manifolds his denudations feeble-mindedly. Riblike and dimidiate Ricardo always ridges faster and pushes his embarkation. Please contact us for more information. Glucose is further converted to starch for storage. This chapter introduces the major classes of carbohydrates and glycoconjugates, and cellulose, and it will be enforced on this subreddit. Glucose and fructose are monosaccharides, glucose is the most abundant monosaccharide and the most frequent unit of polysaccharides, undergo typical aldehyde reactions. Fructose is a ketohexose, Yan C, consult your doctor. Medical speaks to Dr. Add our main listener. First, potatoes, each of these is the basis for two ketohexoses. Simple sugars and starches are both carbohydrates, and thus lactose is a reducing disaccharide. The production of SCFA also results in the acidification of the colonic contents. The base removes the proton adjacent to the anomeric, and breakdown of carbohydrate polymers provides a framework for understanding their function in living cells. How to Convert a Trans Alkene into a Cis Alkene? Accessing this course requires a login. How is the structure of the monosaccharide changed from one form to the other in the human body? Sugars, LLC. Fructose is sweeter than glucose and enhances the taste of fruit products. Sheet Of Paper In A Cage. Understand what a reducing sugar and a reducing end are. Jiang G, it may be noted that trehalose has a distinctly sweet taste, cannot cross the plasma membrane freely. Please enable Cookies and reload the page.
    [Show full text]
  • Synthesis of Densely Substituted Pyridine Derivatives from Nitriles by a Non-Classical [4+2] Cycloaddition/1,5-Hydrogen Shift Strategy
    Synthesis of densely substituted pyridine derivatives from nitriles by a non-classical [4+2] cycloaddition/1,5-hydrogen shift strategy Wanqing Wu ( [email protected] ) South China University of Technology https://orcid.org/0000-0001-5151-7788 Dandan He South China University of Technology Kanghui Duan South China University of Technology Yang Zhou South China University of Technology Meng Li South China University of Technology Huanfeng Jiang South China University of Technology Article Keywords: pyridine derivatives, organic synthesis, medicinal chemistry. Posted Date: March 3rd, 2021 DOI: https://doi.org/10.21203/rs.3.rs-258126/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 1/18 Abstract A novel strategy has been established to assemble an array of densely substituted pyridine derivatives from nitriles and o-substituted aryl alkynes or 1-methyl-1,3-enynes via a non-classical [4 + 2] cycloaddition along with 1,5-hydrogen shift process. The well-balanced anities of two different alkali metal salts enable the C(sp3)-H bond activation as well as the excellent chemo- and regioselectivities. This protocol offers a new guide to construct pyridine frameworks from nitriles with sp3-carbon pronucleophiles, and shows potential applications in organic synthesis and medicinal chemistry. Introduction Compounds containing pyridine core structures, not only widely exist in natural products, pharmaceuticals, and functional materials,1–7 but also serve as useful and valuable building blocks for metal ligands.8,9 For instance, pyridine derivative Actos I10 is a famous drug for the treatment of type 2 diabetes; Bi-(or tri-)pyridines II11–15 are often used as ligands in metal-catalyzed reactions; Kv1.5 antagonist III16 and alkaloid papaverine IV17 are two representative isoquinolines as a promising atrial- selective agent and a smooth muscle relaxant, respectively (Fig.
    [Show full text]
  • TR-470: Pyridine (CASRN 110-86-1) in F344/N Rats, Wistar Rats, And
    NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF PYRIDINE (CAS NO. 110-86-1) IN F344/N RATS, WISTAR RATS, AND B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 March 2000 NTP TR 470 NIH Publication No. 00-3960 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health FOREWORD The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the National Center for Toxicological Research (NCTR), Food and Drug Administration; and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention. In July 1981, the Carcinogenesis Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the relevant programs, staff, and resources from these Public Health Service agencies relating to basic and applied research and to biological assay development and validation. The NTP develops, evaluates, and disseminates scientific information about potentially toxic and hazardous chemicals. This knowledge is used for protecting the health of the American people and for the primary prevention of disease. The studies described in this Technical Report were performed under the direction of the NIEHS and were conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all applicable federal, state, and local health and safety regulations. Animal care and use were in accordance with the Public Health Service Policy on Humane Care and Use of Animals.
    [Show full text]
  • Lecture 6 the Crossed Aldol Reaction and Its Many Variants
    Lecture 6 The Crossed Aldol Reaction and its Many Variants Objectives: By the end of this lecture you will be able to: 1. make an appropriate choice of base to completely enolise carbonyl compounds; 2. use enolates in a crossed aldol reaction; 3. recognise the aldol functional group motif, and its variants, in complex molecules; 4. use the aldol disconnection to simplify a retrosynthetic analysis; 5. use the Reformatski and Mukaiyama aldol reactions in synthesis; 6. draw arrow-pushing mechanisms for all the aldol reactions discussed in this lecture. Introduction We have seen how choosing a base (B-) whose conjugate acid (B−H) is a much poorer acid − i.e. has a much higher pKa − than the proton we wish to abstract, ensures effectively complete deprotonation of the α-C−H of a carbonyl compound to provide the corresponding enolate. By completely enolising the carbonyl group, we can suppress self-condensation aldol processes, and instead use a different electrophile such as an aldehyde to form a β-hydroxy carbonyl compound. This reaction sequence is identical in basic mechanism to the intramolecular aldol processes that we discussed in previous lectures. It is now described as a crossed aldol condensation because the electrophile is a different carbonyl compound to the one that was used to form the nucleophilic enolate. This reaction, and its many variants, provides one of the most important methods for preparing C−C bonds. Pattern Recognition The aldol reaction and its many variants are very useful reactions in synthesis. You need to be able to identify the patterns or functional group motifs where this type of bond-forming process can be used.
    [Show full text]
  • Robert Burns Woodward
    The Life and Achievements of Robert Burns Woodward Long Literature Seminar July 13, 2009 Erika A. Crane “The structure known, but not yet accessible by synthesis, is to the chemist what the unclimbed mountain, the uncharted sea, the untilled field, the unreached planet, are to other men. The achievement of the objective in itself cannot but thrill all chemists, who even before they know the details of the journey can apprehend from their own experience the joys and elations, the disappointments and false hopes, the obstacles overcome, the frustrations subdued, which they experienced who traversed a road to the goal. The unique challenge which chemical synthesis provides for the creative imagination and the skilled hand ensures that it will endure as long as men write books, paint pictures, and fashion things which are beautiful, or practical, or both.” “Art and Science in the Synthesis of Organic Compounds: Retrospect and Prospect,” in Pointers and Pathways in Research (Bombay:CIBA of India, 1963). Robert Burns Woodward • Graduated from MIT with his Ph.D. in chemistry at the age of 20 Woodward taught by example and captivated • A tenured professor at Harvard by the age of 29 the young... “Woodward largely taught principles and values. He showed us by • Published 196 papers before his death at age example and precept that if anything is worth 62 doing, it should be done intelligently, intensely • Received 24 honorary degrees and passionately.” • Received 26 medals & awards including the -Daniel Kemp National Medal of Science in 1964, the Nobel Prize in 1965, and he was one of the first recipients of the Arthur C.
    [Show full text]
  • Toxicological Profile for Pyridine
    TOXICOLOGICAL PROFILE FOR PYRIDINE Agency for Toxic Substances and Disease Registry U.S. Public Health Service September 1992 ii DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. 1 1. PUBLIC HEALTH STATEMENT This Statement was prepared to give you information about pyridine and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,177 sites on its National Priorities List (NPL). Pyridine has been found at 4 of these sites. However, we do not know how many of the 1,177 NPL sites have been evaluated for pyridine. As EPA evaluates more sites, the number of sites at which pyridine is found may change. This information is important for you to know because pyridine may cause harmful health effects and because these sites are potential or actual sources of human exposure to pyridine. When a chemical is released from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment as a chemical emission. This emission, which is also called a release, does not always lead to exposure. You can be exposed to a chemical only when you come into contact with the chemical. You may be exposed to it in the environment by breathing, eating, or drinking substances containing the chemical or from skin contact with it. If you are exposed to a hazardous chemical such as pyridine, several factors will determine whether harmful health effects will occur and what the type and severity of those health effects will be.
    [Show full text]
  • Aldol Condensation
    Chemistry 212 Laboratory Dibenzalacetone via Crossed Aldol Condensation Prelab: Calculate the amounts of all chemicals needed in measurable amounts (i.e. grams or milliliters rather than moles.) Introduction: Aldol condensations are important in organic synthesis, providing a good way to form carbon–carbon bonds. The "aldol" (aldehyde + alcohol) product is a structural unit found in many naturally occurring molecules and pharmaceuticals, and is therefore important. In an Aldol condensation an enolate ion reacts with a carbonyl compound to form a β- hydroxyaldehyde or β-hydroxyketone, followed by dehydration to give a conjugated enone. The general equation is shown in Figure 1. O O O R" B: H R R'" R "R R'" loss of H2O H R' R' Figure 1. The equation for the Aldol Condensation. The reaction involves the nucleophilic addition of an enolate to an aldehyde to form a β-hydroxy carbonyl. The β-hydroxy carbonyl is readily dehydrated under mild conditions. The aldol reaction occurs under both acidic and basic conditions as seen in Figure 2. ENOL pathway (reacts in H O protonated OH form) O O catalytic H+ O O H H R' H2O lost R' R R R' R R H aldol addition product aldol condensation product ENOLATE pathway O O M O M O base O H R' R R' R R enolate H Figure 2. The Aldol reaction and subsequent dehydration under acidic and basic conditions. The reaction we will be doing this week involves the reaction between benzaldehyde and acetone to do a double Aldol Condensation. The overall equation is shown in Figure 3.
    [Show full text]
  • MINDO-Forces Study on the Substituent Effect in the Keto-Enol Tautomerism of Acetyl Derivatives
    MINDO-Forces Study on the Substituent Effect in the Keto-Enol Tautomerism of Acetyl Derivatives Wasim F. Al-Halasah, Ali Mahasnah, and Salim M. Khalil Chemistry Department, College of Science, University of Mutah, Karak, Jordan Reprint requests to Prof. S.M.K.; E-mail: [email protected] Z. Naturforsch. 59a, 299 – 308 (2004); received February 11, 2004 MINDO-Forces calculations with complete geometry optimization have been performed on ac- etaldehyde, vinyl alcohol and acetyl derivatives CH3COX(X=H, F, OH, CN, NH2,NO2,CH3, CF3,OCH3). It was found that acetaldehyde is more stable than vinyl alcohol by 10.451 kcal/mol. Thermodynamically, keto tautomers are more stable than their enol counterparts. This agrees with theoretical calculations. The electron releasing substituents tend to stabilize keto tautomers, while the electron withdrawing substituents tend to destabilize the keto tautomers, relative to the parent. Geometrical parameters, heats of formation, electron densities, Gibbs free energies and orbital ener- gies (HOMO-LUMO) are reported. Key words: Acetaldehyde; Vinyl Alcohol; Keto-Enol Tautomerism; Acetyl Derivative. 1. Introduction 311++G∗∗//MP2(full)/6-31G∗ levels of theory, ac- etaldehyde 1 is found to lie 11.2 and 13.35 kcal/mol Tautomerism refers to the equilibrium between two below vinyl alcohol 2 on the potential energy sur- different structures of the same compound. It is a pro- face, respectively. Recent B3LYP and G2MP2 calcu- totropic rearrangement in which a hydrogen at the α- lations [14] show that acetaldehyde 1 lies 10.4 and position to a carbon-heteroatom double bond migrates 11.1 kcal/mol below vinyl alcohol 2, respectively.
    [Show full text]
  • Determination of Solvent Effects on Ketoðenol Equilibria of 1,3-Dicarbonyl Compounds Using NMR: Revisiting a Classic Physical C
    In the Laboratory Determination of Solvent Effects on Keto–Enol Equilibria W of 1,3-Dicarbonyl Compounds Using NMR Revisiting a Classic Physical Chemistry Experiment Gilbert Cook* and Paul M. Feltman Department of Chemistry, Valparaiso University, Valparaiso, IN 46383; *[email protected] “The influence of solvents on chemical equilibria was discovered in 1896, simultaneously with the discovery of keto–enol tautomerism in 1,3-dicarbonyl compounds” (1). The solvents were divided into two groups according to their ability to isomerize compounds. The study of the keto–enol tautomerism of β-diketones and β-ketoesters in a variety of solvents using proton NMR has been utilized as a physical Figure 1. The β-dicarbonyl compounds studied in the experiment. chemistry experiment for many years (2, 3). The first reported use of NMR keto–enol equilibria determination was by Reeves (4). This technique has been described in detail in an experiment by Garland, Nibler, and Shoemaker (2). panded (i) to give an in-depth analysis of factors influencing The most commonly used β-diketone for these experi- solvent effects in tautomeric equilibria and (ii) to illustrate ments is acetylacetone (Scheme I). Use of proton NMR is a the use of molecular modeling in determining the origin of viable method for measuring this equilibrium because the a molecule’s polarity. The experiment’s original benefits of tautomeric keto–enol equilibrium is slow on the NMR time using proton NMR as a noninvasive method of evaluating scale, but enol (2a)–enol (2b) tautomerism is fast on this scale equilibrium are maintained. (5). It has been observed that acyclic β-diketones and β- Experimental Procedure ketoesters follow Meyer’s rule of a shift in the tautomeric equi- librium toward the keto tautomer with increasing solvent Observations of the solvent effects for three other 1,3- polarity (6).
    [Show full text]
  • Thiocyanate Pyridine Complexes
    W&M ScholarWorks Undergraduate Honors Theses Theses, Dissertations, & Master Projects 5-2017 Structural Comparison of Copper(II) Thiocyanate Pyridine Complexes Joseph V. Handy College of WIlliam & Mary Follow this and additional works at: https://scholarworks.wm.edu/honorstheses Part of the Inorganic Chemistry Commons Recommended Citation Handy, Joseph V., "Structural Comparison of Copper(II) Thiocyanate Pyridine Complexes" (2017). Undergraduate Honors Theses. Paper 1100. https://scholarworks.wm.edu/honorstheses/1100 This Honors Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Undergraduate Honors Theses by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Structural Comparison of Copper(II) Thiocyanate Pyridine Complexes A thesis submitted in partial fulfillment of the requirement for the degree of Bachelor of Science in Chemistry from The College of William & Mary by Joseph Viau Handy Accepted for ____________________________ ________________________________ Professor Robert D. Pike ________________________________ Professor Deborah C. Bebout ________________________________ Professor David F. Grandis ________________________________ Professor William R. McNamara Williamsburg, VA May 3, 2017 1 Table of Contents Table of Contents…………………………………………………...……………………………2 List of Figures, Tables, and Charts………………………………………...…………………...4 Acknowledgements….…………………...………………………………………………………6
    [Show full text]
  • Efficient Synthesis of Novel Pyridine-Based Derivatives Via
    molecules Article Efficient Synthesis of Novel Pyridine-Based Derivatives via Suzuki Cross-Coupling Reaction of Commercially Available 5-Bromo-2-methylpyridin-3-amine: Quantum Mechanical Investigations and Biological Activities Gulraiz Ahmad 1, Nasir Rasool 1,*, Hafiz Mansoor Ikram 1, Samreen Gul Khan 1, Tariq Mahmood 2, Khurshid Ayub 2, Muhammad Zubair 1, Eman Al-Zahrani 3, Usman Ali Rana 4, Muhammad Nadeem Akhtar 5 and Noorjahan Banu Alitheen 6,* 1 Department of Chemistry, Government College University Faisalabad, Faisalabad 38000, Pakistan; [email protected] (G.A.); [email protected] (H.M.I.); [email protected] (S.G.K.); [email protected] (M.Z.) 2 Department of Chemistry, COMSATS Institute of Information Technology, University Road, Tobe Camp, 22060 Abbottabad, Pakistan; [email protected] (T.M.); [email protected] (K.A.) 3 Chemistry Department, Faculty of Science, Taif University, 888-Taif, Saudi Arabia; [email protected] 4 Sustainable Energy Technologies Center, College of Engineering, P.O. Box 800, King Saud University, Riyadh 11421, Saudi Arabia; [email protected] 5 Faculty of Industrial Sciences & Technology, University Malaysia Pahang, Lebuhraya Tun, Razak 26300, Kuantan Pahang, Malaysia; [email protected] 6 Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, Serdang, Selangor Darul Ehsan 43400, Malaysia * Correspondence: [email protected] (N.R.); [email protected] (N.B.A.); Tel.: +92-332-7491790 (N.R.); +60-3-8946-7471 (N.B.A.); Fax: +92-41-9201032 (N.R.); +60-3-8946-7510 (N.B.A.) Academic Editor: Diego Muñoz-Torrero Received: 20 November 2016; Accepted: 6 January 2017; Published: 27 January 2017 Abstract: The present study describes palladium-catalyzed one pot Suzuki cross-coupling reaction to synthesize a series of novel pyridine derivatives 2a–2i, 4a–4i.
    [Show full text]