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Monday 15 August 2016

High Throughput Enzymatic Enantiomeric Excess: Quick-ee

.
High throughput screening techniques (HTS) are fast and efficient alternatives to evaluate enzymatic activities. Here, this technique is applied to obtain enantiomeric excess and conversions values with chiral fluorogenic probes and a non fluorogenic competitor, which was named Quick-ee. The fluorescent signal reveals of the enantioselectivity of the enzyme. Details are presented in the Article High Throughput Enzymatic Enantiomeric Excess: Quick-ee by Maria L. S. de O. Lima, Caroline C. da S. Gonçalves, Juliana C. Barreiro, Quezia Bezerra Cass and Anita Jocelyne Marsaioli on page 319.

http://dx.doi.org/10.5935/0103-5053.20140282


Cover Article
J. Braz. Chem. Soc. 2015, 26(2), 319-324

High Throughput Enzymatic Enantiomeric Excess: Quick-ee

Maria L. S. O. Lima; Caroline C. S. Gonçalves; Juliana C. Barreiro; Quezia B. Cass; Anita J. Marsaioli
Lima MLSO, Gonçalves CCS, Barreiro JC, Cass QB, Marsaioli AJ. High Throughput Enzymatic Enantiomeric Excess: Quick-ee.J. Braz. Chem. Soc. 2015;26(2):319-324
/////////////High Throughput,  Enzymatic,  Enantiomeric Excess,  Quick-ee
http://jbcs.sbq.org.br/imagebank/pdf/v26n2a14.pdf
http://jbcs.sbq.org.br/imagebank/pdf/v26n2a14-Sup01.pdf

Friday 29 July 2016

Ring-locking enables selective anhydrosugar synthesis from carbohydrate pyrolysis


Ring-locking enables selective anhydrosugar synthesis from carbohydrate pyrolysis

Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC01600F, Paper
Li Chen, Jinmo Zhao, Sivaram Pradhan, Bruce E. Brinson, Gustavo E. Scuseria, Z. Conrad Zhang, Michael S. Wong
The nonselective nature of glucose pyrolysis chemistry can be controlled by preventing the sugar ring from opening and fragmenting.

Ring-locking enables selective anhydrosugar synthesis from carbohydrate pyrolysis

*Corresponding authors
aDepartment of Chemical and Biomolecular Engineering, Rice University, Houston, USA
E-mail: mswong@rice.edu
bDepartment of Chemistry, Rice University, Houston, USA
cDalian National Laboratory of Clean Energy, Dalian Institute of Chemical Physics, Dalian, China
E-mail: zczhang@dicp.ac.cn
dDepartment of Civil and Environmental Engineering, Rice University, Houston, USA
eDepartment of Materials Science and NanoEngineering, Rice University, Houston, USA
Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC01600F
The selective production of platform chemicals from thermal conversion of biomass-derived carbohydrates is challenging. As precursors to natural products and drug molecules, anhydrosugars are difficult to synthesize from simple carbohydrates in large quantities without side products, due to various competing pathways during pyrolysis. Here we demonstrate that the nonselective chemistry of carbohydrate pyrolysis is substantially improved by alkoxy or phenoxy substitution at the anomeric carbon of glucose prior to thermal treatment. Through this ring-locking step, we found that the selectivity to 1,6-anhydro-β-D-glucopyranose (levoglucosan, LGA) increased from 2% to greater than 90% after fast pyrolysis of the resulting sugar at 600 °C. DFT analysis indicated that LGA formation becomes the dominant reaction pathway when the substituent group inhibits the pyranose ring from opening and fragmenting into non-anhydrosugar products. LGA forms selectively when the activation barrier for ring-opening is significantly increased over that for 1,6-elimination, with both barriers affected by the substituent type and anomeric position. These findings introduce the ring-locking concept to sugar pyrolysis chemistry and suggest a chemical-thermal treatment approach for upgrading simple and complex carbohydrates.
////////Ring-locking ,  selective anhydrosugar, carbohydrate pyrolysis, synthesis

Tuesday 19 July 2016

2-chloro-3-(3-chloro-5-iodophenoxy)-4-(trifluoromethyl)pyridine




2-chloro-3-(3-chloro-5-iodophenoxy)-4-(trifluoromethyl)pyridine


1H NMR (400 MHz, DMSO-d6) δ 8.65 (d, J = 4.9 Hz, 1H), 7.95 (t, J = 4.5 Hz, 1H), 7.60 (dd, J = 1.3, 2.9Hz, 1H), 7.38 (br. s., 1H), 7.29 - 7.15 (m, 1H)


13C NMR (101 MHz, DMSO-d6) δ 157.10, 148.02, 145.37, 142.46 (q, JC-F = 2.0 Hz), 135.00, 132.82 (q,JC-F = 33.2 Hz), 131.69, 122.91, 121.59 (q, JC-F = 4.0 Hz), 121.34 (q, JC-F = 273.7 Hz), 115.47, 95.72

19F NMR (377 MHz, DMSO-d6) δ -61.96 (s, 1F)
mp 71.69-79.27 °C






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Monday 11 July 2016

Nickel-Catalyzed Decarbonylative Suzuki–Miyaura Coupling of Amides To Generate Biaryls

Thumbnail image of graphical abstract








Shi et al. have reported a nickel-catalyzed decarbonylative Suzuki–Miyaura reaction which uses an N-aroylpiperidine-2,6-dione as the coupling partner for the boronic acid ( Angew. Chem., Int. Ed. 2016556959−6963).
The method is attractive from the point of view of the stability of N-aroylpyrrolidine-2,5-diones toward storage and manipulation and the flexibility they add to the chemist’s toolbox, given their preparation from a different group of precursors to aryl halides or triflates.
Notably, the reaction uses an air-stable and inexpensive nickel catalyst, and the reactions tolerate the presence of water. While a standard reaction temperature of 150 °C is quoted, the use of temperatures as low as 80 °C also seem to be possible. Coupling efficiency is reported to be adversely affected when the aromatic rings of both of the coupling partners bear electron-donating substituents.
Ortho substituents on the aromatic rings seem to be beneficial as they facilitate decarbonylation as part of the cross-coupling. Oxidative addition into the N–C(aroyl) bond of the amide is proposed as initiating the catalytic cycle and is possible on account of a reduction in the resonance stabilization of the N-aroyl functionality versus a conventional aromatic amide.

Suzuki–Miyaura Coupling

Synthesis of Biaryls through Nickel-Catalyzed Suzuki–Miyaura Coupling of Amides by Carbon–Nitrogen Bond Cleavage (pages 6959–6963)Shicheng Shi, Guangrong Meng and Prof. Dr. Michal Szostak
Version of Record online: 21 APR 2016 | DOI: 10.1002/anie.201601914
Thumbnail image of graphical abstract
Breaking and making: The first nickel-catalyzed Suzuki–Miyaura coupling of amides for the synthesis of biaryl compounds through N−C amide bond cleavage is reported. The reaction tolerates a wide range of sensitive and electronically diverse substituents on both coupling partners.
STR1
STR1
1H NMR (500 MHz, CDCl3) δ 7.70 (s, 4 H), 7.61 (d, J = 7.3 Hz, 2 H), 7.48 (t, J = 7.6 Hz, 2 H), 7.42 (t, J = 7.3 Hz, 1 H).

STR1
13C NMR (125 MHz, CDCl3) δ 144.87, 139.92, 129.48 (q, J F = 32.5 Hz), 129.13, 128.32, 127.56, 127.42, 125.83 (q, J F = 3.8 Hz), 124.46 (q, J F = 270.0 Hz).

STR1
19F NMR (471 MHz, CDCl3) δ -62.39.



Szostak_PhotoMichal Szostakemail: michal.szostak@rutgers.edu
office: Olson 204
  1. Department of Chemistry, Rutgers University, Newark, NJ, USA

CHEM_BANNER

Research Interests

The central theme of our research is synthetic organic and organometallic chemistry with a focus on the development of new synthetic methods based on transition metal catalysis and various aspects of transition metal mediated free radical chemistry and their application to the synthesis of biologically active molecules.

Selected Publications

  1. Graphene-Catalyzed Direct Friedel-Crafts Alkylation Reactions: Mechanism, Selectivity and Synthetic Utility. Hu, F.; Patel, M.; Luo, F.; Flach, C.; Mendelsohn, R.; Garfunkel, E.; He, H.; Szostak, M. J. Am. Chem. Soc. 2015137 [doi]
  2. General Olefin Synthesis by the Palladium-Catalyzed Heck Reaction of Amides: Sterically-Controlled Chemoselective N-C Activation. Meng, G.; Szostak, M. Angew. Chem. Int. Ed. 201554[doi]
  3. Aminoketyl Radicals in Organic Synthesis: Stereoselective Cyclization of 5- and 6-Membered Cyclic Imides to 2-Azabicycles using SmI2-H2O. Shi S.; Szostak, M. Org. Lett. 201517, 5144 [doi]
  4. Sterically-Controlled Pd-Catalyzed Chemoselective Ketone Synthesis via N-C Cleavage in Twisted Amides. Meng, G.; Szostak, M. Org. Lett. 201517 [doi]
  5. Recent Developments in the Synthesis and Reactivity of Isoxazoles: Metal Catalysis and Beyond.Hu, F.; Szostak, M. Adv. Synth. Catal. 2015357, 2583. [doi]
  6. Determination of Structures and Energetics of Small- and Medium-Sized One-Carbon Bridged Twisted Amides using ab Initio Molecular Orbital Methods. Implications for Amidic Resonance along the C-N Rotational Pathway. Szostak, R.; Aubé, J.; Szostak, M. J. Org. Chem. 201580, 7905. [doi]
  7. An Efficient Computational Model to Predict Protonation at the Amide Nitrogen and Reactivity along the C-N Rotational Pathway. Szostak, R.; Aubé, J.; Szostak, M. Chem. Commun. 201551, 6395.[doi]
  8. Pd-Catalyzed C-H Activation: Expanding the Portfolio of Metal-Catalyzed Functionalization of Unreactive C-H Bonds by Arene-Chromium π-Complexation. Hu, F.; Szostak, M. ChemCatChem20157, 1061. [doi]
  9. Highly Chemoselective Reduction of Amides (Primary, Secondary and Tertiary) to Alcohols using SmI2/H2O/Amine under Mild Conditions. Szostak, M.; Spain, M.; Eberhart, A. J.; Procter, D. J. J. Am. Chem. Soc. 2014136, 2268. [doi]
  10. Substrate-Directable Electron Transfer Reactions. Dramatic Rate Enhancement in the Chemoselective Reduction of Cyclic Esters using SmI2-H2O: Mechanism, Scope and Synthetic Utility. Szostak, M.; Spain, M.; Choquette, K. A.; Flowers, R. A., II; Procter, D. J. J. Am. Chem. Soc.2013135, 15702. [doi]
  11. Selective Reduction of Barbituric Acids using SmI2-H2O: Synthesis, Reactivity and Structural Analysis of Tetrahedral Adducts. Szostak, M.; Spain, M.; Behlendorf, M; Procter, D. J. Angew. Chem. Int. Ed. 201352, 12559. [doi]
  12. Non-Classical Lanthanide(II) Iodides: Uncovering the Importance of Proton Donors in TmI2-Promoted Electron Transfer. Facile C-N Bond Cleavage in Unactivated Amides. Szostak, M.; Spain, M.; Procter, D. J. Angew. Chem. Int. Ed. 201352, 7237. [doi]
  13. Chemistry of Bridged Lactams and Related Heterocycles. Szostak, M.; Aubé, J. Chem. Rev. 2013,113, 5701. [doi]
For more detail, please see the Szostak Group Web Site 


DSC_0080




GROUP


Prof. Michal Szostak
Assistant Professor
Ph.D., University of Kansas (2009) with Jeffrey Aubé
Postdoctoral, Princeton University (2010) with David MacMillan
Postdoctoral, University of Manchester (2011-2014) with David Procter 
Postdoctoral Researchers
Dr. Feng Hu
Ph.D., Nanjing University, 2009 (Z. Huang)
Postdoctoral, Shanghai Institute of Materia Medica (Y. Hu)
Research Assistant Professor, SIOC (Q. Shen)
Postdoctoral, Lamar University (X. Lei) 
Dr. Pradeep Nareddy
Ph.D., University of Geneva, 2013 (C. Mazet)
Postdoctoral, Leipzig University (C. Schneider) 
Graduate Students
Shicheng Shi
M.S., SIOC, 2013 (R. Wang)
B.S., Nanjing Agriculture University, 2010 
Guangrong Meng
M.S., Fudan University, 2014 (Q. Zhang)
B.S., Dalian Medical University, 2011 
Chengwei Liu
M.S., Soochow University, 2014 (Y. Yao)
B.S., Zaozhuang University, 2011 
Undergraduate Students
Syed Huq (Rutgers, Chemistry, 2014-present)
Marcel Achtenhagen (Rutgers, Chemistry, 2015-present) 
Visiting Students
Yongmei Liu (Yangzhou University, R. Liu)

//////Nickel-Catalyzed,  Decarbonylative Suzuki–Miyaura Coupling,  Amides, Biaryls

Wednesday 6 July 2016

Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review

imageHighlights
Modification of BHT has a significant multivariate effect on antioxidant efficiency.
BDE is the key to rational design and development of antioxidants.
Antioxidant performance of BHT is mainly depending on 13 very crucial parameters.
MPAO is a promising way to increase antioxidant and pharmacological activities.

Abstract

Hindered phenols find a wide variety of applications across many different industry sectors. Butylated hydroxytoluene (BHT) is a most commonly used antioxidant recognized as safe for use in foods containing fats, pharmaceuticals, petroleum products, rubber and oil industries. In the past two decades, there has been growing interest in finding novel antioxidants to meet the requirements of these industries. To accelerate the antioxidant discovery process, researchers have designed and synthesized a series of BHT derivatives targeting to improve its antioxidant properties to be having a wide range of antioxidant activities markedly enhanced radical scavenging ability and other physical properties. Accordingly, some structure–activity relationships and rational design strategies for antioxidants based on BHT structure have been suggested and applied in practice. We have identified 14 very sensitive parameters, which may play a major role on the antioxidant performance of BHT. In this review, we attempt to summarize the current knowledge on this topic, which is of significance in selecting and designing novel antioxidants using a well-known antioxidant BHT as a building-block molecule. Our strategy involved investigation on understanding the chemistry behind the antioxidant activities of BHT, whether through hydrogen or electron transfer mechanism to enable promising anti-oxidant candidates to be synthesized.

Volume 101, 28 August 2015, Pages 295–312
Review article

Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review

  • aNanotechnology & Catalysis Research Centre, (NANOCAT), University of Malaya, Block 3A, Institute of Postgraduate Studies Building, 50603 Kuala Lumpur, Malaysia
  • bDepartment of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
  • cDivision of Human Biology, Faculty of Medicine, International Medical University, 57000 Kuala Lumpur, Malaysia
  • dDrug Design and Development Research Group, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
  • http://www.sciencedirect.com/science/article/pii/S022352341530101X
doi:10.1016/j.ejmech.2015.06.026
SEE
https://www.researchgate.net/publication/278050005_ChemInform_Abstract_Understanding_the_Chemistry_Behind_the_Antioxidant_Activities_of_Butylated_Hydroxytoluene_BHT_A_Review/figures












///////////Antioxidant, Butylated hydroxytoluene, Free radical, Reactive oxygen species, Phenol

Tuesday 7 June 2016

Multicomponent Multicatalyst Reactions (MC)2R: One-Pot Synthesis of 3,4-Dihydroquinolinones


Multicomponent Multicatalyst Reactions (MC)2R: 
One-Pot Synthesis of 3,4-Dihydroquinolinones
Lei Zhang, Lorenzo Sonaglia, Jason Stacey, and Mark Lautens Org. Lett. 2013152128-2131. DOI:10.1021/ol4006008 .

A Rh/Pd/Cu catalyst system led to an efficient synthesis of dihydroquinolinones in one-pot, two operations. The reaction features the first triple metal-catalyzed transformations in one reaction vessel, without any intermediate workup. The conjugate-addition/amidation/amidation reaction sequence is highly modular, divergent, and practical.


Multicomponent Multicatalyst Reactions (MC)2R: One-Pot Synthesis of 3,4-Dihydroquinolinones

Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada
Org. Lett.201315 (9), pp 2128–2131
DOI: 10.1021/ol4006008
Publication Date (Web): April 19, 2013
Copyright © 2013 American Chemical Society
http://pubs.acs.org/doi/abs/10.1021/ol4006008




Mark Lautens


Mark Lautens , O.C.


University Professor
J. Bryan Jones Distinguished Professor
AstraZeneca Professor of Organic Chemistry
NSERC/Merck-Frosst Industrial Research Chair







Department of Chemistry
Davenport Chemical Laboratories
80 St. George St.
University of Toronto
Toronto, Ontario
M5S 3H6

Tel: (416) 978-6083
Fax: (416) 946-8185
E-Mail: mlautens@chem.utoronto.ca


Curriculum Vitae

Personal

Place and Date of BirthHamilton, Ontario, CanadaJuly 9, 1959

Education

Harvard UniversityNSERC PDF with D. A. Evans1985 - 1987
University of Wisconsin-MadisonPh.D. with B. M. Trost1985
University of GuelphB.Sc. - Distinction1981

Academic Positions

J. Bryan Jones Distinguished ProfessorUniversity of Toronto2013 - 2018
University ProfessorUniversity of Toronto2012 - present
NSERC/Merck Frosst Industrial Research ChairNSERC/Merck Frosst2003 - 2013
AstraZeneca Professor of Organic SynthesisUniversity of Toronto1998 - present
ProfessorUniversity of Toronto1995 - 1998
Associate ProfessorUniversity of Toronto1992 - 1995
Assistant ProfessorUniversity of Toronto1987 - 1992

Awards & Honors

University of Toronto Alumni Faculty AwardUniversity of Toronto2016
CIC Catalysis AwardCSC2016
Officer of the Order of CanadaGovernor General2014
Killam Research FellowshipCanada Council for the Arts2013-2015
CIC MedalChemical Institute of Canada2013
Fellow of the Royal Society of UKRoyal Society of Chemistry2011
Pedler AwardRoyal Society of Chemistry2011
Senior Scientist AwardAlexander von Humboldt Foundation
Berlin, Aachen and Gottingen
2009-2014
Visiting ProfessorUniversity of Berlin2009
Visiting ProfessorUniversité de Marseilles2008
ICIQ Summer SchoolICIQ Tarragona, Spain2008
Attilio Corbella Summer School ProfessorItalian Chemical Society2007
Arthur C. Cope Scholar AwardAmerican Chemical Society2006
Alfred Bader AwardCanadian Society for Chemistry2006
R. U. Lemieux AwardCanadian Society for Chemistry2004
Solvias PrizeSolvias AG2002
Fellow of the Royal Society of CanadaRoyal Society of Canada2001

Areas of Research Interest and Expertise

  • new synthetic methods
  • metal catalyzed cycloaddition and annulation reactions
  • asymmetric catalysis with focus on rhodium, nickel and palladium catalysts
  • cyclopropane synthesis and reactions
  • hydrometallation reactions
  • reactions of organosilicon and organotin compounds
  • fragmentation reactions
  • new routes to medicinally/biologically interesting compounds
  • heterocycle synthesis using metal catalysts
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Saturday 4 June 2016

Heterogeneous catalytic approaches in C-H activation reactions

Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC00385K, Critical Review
Stefano Santoro, Sergei I. Kozhushkov, Lutz Ackermann, Luigi Vaccaro
This review summarizes the development of user-friendly, recyclable and easily separable heterogeneous catalysts for C-H activation during the last decade until December 2015.

http://pubs.rsc.org/en/Content/ArticleLanding/2016/GC/C6GC00385K?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Despite the undisputed advances and progress in metal-catalyzed C–H functionalizations, this atom-economical approach had thus far largely been developed with the aid of various metal catalysts that were operative in a homogeneous fashion. 

While thereby major progress was accomplished, these catalytic systems featured notable disadvantages, such as low catalyst recyclability. This review summarizes the development of user-friendly, recyclable and easily separable heterogeneous catalysts for C–H activation.

This strategy was characterized by a remarkably broad substrate scope, considerable levels of chemo- and site-selectivities and proved applicable to C–C as well as C–heteroatom formation processes. 

Thus, recyclable catalysts were established for arylations, hydroarylations, alkenylations, acylations, nitrogenations, oxygenations, or halogenations, among others. The rapid recent progress in selective heterogeneous C–H functionalizations during the last decade until December 2015 is reviewed.


Heterogeneous catalytic approaches in C–H activation reactions

*
Corresponding authors
a
Laboratory of Green Synthetic Organic Chemistry, Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto, 8 – 06123 Perugia, Italy 
E-mail: luigi.vaccaro@unipg.it
Web: http://www.dcbb.unipg.it/greensoc
b
Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany 
E-mail: Lutz.Ackermann@chemie.uni-goettingen.de
Web: http://www.ackermann.chemie.uni-goettingen.de
Green Chem., 2016, Advance Article

DOI: 10.1039/C6GC00385K     




















Laboratory of Green Synthetic Organic Chemistry, Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto, 8 – 06123 Perugia, Italy 
E-mail: luigi.vaccaro@unipg.it
Web: http://www.dcbb.unipg.it/greensoc

Extra clips
 C-H Activation :: Wiley-VCH Hot Topics






 
 The Yu Lab
www.scripps.edu
"Ligand-Enabled Triple C-H Activation Reactions: One-Pot Synthesis of Diverse 4-Aryl-2-quinolinones from Propionamides" Angew. Chem. Int. Ed. 2014, 53, ...

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