Archive for the ‘Hot articles’ Category

Revitalizing palladium-catalyzed α-arylation of enolates to generate diverse isoquinoline-based compounds

Research efforts carried out by Professor Timothy Donohoe of Oxford University have been focussed on connecting new methodologies in organic synthesis and catalysis with impactful applications to the fields of medicinal chemistry and natural product synthesis.

One of the group’s most recent endeavors includes the development of a generalized strategy to access highly functionalized and diverse isoquinoline cores without the use of expensive and highly-specialized starting materials.

The isoquinoline motif and its derivatives are ubiquitous in a number of natural products, pharmaceutical agents, and chiral catalyst ligands. However, classical syntheses are often centered on electrophilic aromatic substitution of electron-rich systems, resulting in limited chemical diversity in accessible products. New routes are still highly desirable and a resurgence in synthetic efforts has resulted in a number of notable contributions using modern synthetic methodology.

In 2012, Prof. Donohoe and coworkers reported a sequential palladium-catalyzed α-arylation of enolates and cyclization to access isoquinolines based on chemistry originally and independently reported by Buckwald, Hartwig and Miura in 1997. Though a powerful reaction, it remained underutilized in the assembly of complex aromatic compounds. Using clever reaction engineering, Donohoe and coworkers envisioned synthesizing a psuedo-1,5-dicarbonyl accessible through α-arylation of enolizable ketones with aryl halides possessing a protected aldehyde or ketone in the ortho-position. In addition, trapping with reactive electrophiles resulted in functionalization at the C4 position. This methodology can be carried out in one pot, tolerates a wide range of substituents and most notably, provides a route to synthetically challenging electron-deficient isoquinoline scaffolds.

Palladium-catalyzed enolate arylation as a key C–C bond-forming reaction for the synthesis of isoquinolines

Their current study presents significant extensions of this earlier work and further demonstrates the innovation possible through transition metal catalysis in enabling the construction of complex architectures in interesting ways. The three- and four-component coupling procedures involve multiple bond formations in one pot from largely commercially available starting materials. Reaction versatility is demonstrated through the use of ketone, ester or nitrile enolates as well as electron-rich, electron-deficient or even sterically hindered aryl halides and in situ functionalization of intermediates to directly access a number of highly functionalized isoquinoline based compounds.

In addition to rejuvenating interesting and underexplored chemistry, Prof. Donohoe and coworkers have appreciably impacted the areas of natural product synthesis and medicinal chemistry through their innovative and streamlined synthesis of isoquinoline-based compounds and it will be interesting to see where their future endeavours will lead.


To find out more see:

Palladium-catalyzed enolate arylation as a key C–C bond-forming reaction for the synthesis of isoquinolines
Ben S. Pilgrim, Alice E. Gatland, Carlos H. A. Esteves, Charlie T. McTernan, Geraint R. Jones, Matthew R. Tatton, Panayiotis A. Procopiou and Timothy J. Donohoe
DOI: 10.1039/C5OB02320C


Victoria Corless is currently completing her Ph.D. in organic chemistry with Prof. Andrei Yudin at The University of Toronto. Her research is centred on the synthesis of kinetically amphoteric molecules, which offer a versatile platform for the development of chemoselective transformations with particular emphasis on creating novel biologically active molecules.

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Applying old tricks to new problems: Acyl Fluorides in Sterically Hindered Amide Coupling

It comes as no surprise to those with a background in organic or medicinal chemistry that one of the most important and often-overlooked synthetic transformations is the formation of amide bonds.

Amide linkages are one of the most prolific moieties in the synthesis of pharmaceuticals and biologically active molecules. However, despite their prevalence there remain synthetic challenges, as even the simplest amides can be difficult to make.

A group at the University of Southern Denmark led by Prof. Trond Ulven has developed a protocol for amide coupling through in situ formation of acyl fluorides.

Initially, the researchers were working toward the synthesis of a molecular inhibitor for the free fatty acid receptor 2 (FFA2/GPR43), which has recently generated some interest as a target for treating various metabolic disorders.

While attempting the synthesis of an intermediate, coupling between their sterically hindered and sensitive carboxylic acid with an electron deficient and hindered amide understandably led to unsatisfactory results using standard coupling procedures.

Given the multiple steps required to generate both intermediates, the group decided to explore alternative methods to solve their problem. Indeed, acyl fluorides proved to be ideal as they behave like activated esters due to the unique nature of the carbonyl-fluoride bond while also minimizing steric hindrance between the two coupling partners.

Literature protocols are available for the generation of acyl fluorides and there are disadvantages associated with some. In recent years however, a number of alternative fluorinating agents have been reported that are capable of generating the acyl fluoride in situ under mild reaction conditions.

Prof. Ulven’s group was able to further improve the efficiency of this methodology by utilizing an alternative fluorinating agent, BTFFH, which is normally used in solid-phase peptide synthesis. This reagent reduces byproduct formation observed with reagents such as DAST, Deoxo-Fluor and XtalFluor-E. High conversions and isolated yields were obtained as a result and Ulven’s method was also successfully applied to amide coupling reactions previously reported as low yielding.

There is still a need for chemists to develop better ways to synthesize complex amide-containing structures without the need for external reagents. In the meantime, solutions such as these overcome synthetic challenges and are critical to further development and understanding in organic reaction design.


To find out more see:

A protocol for amide bond formation with electron deficient amines and sterically hindered substrates
Maria E. Due-Hansen, Sunil K. Pandey, Elisabeth Christiansen, Rikke Andersen, Steffen V. F. Hansen and Trond Ulven
DOI: 10.1039/C5OB02129D


Victoria Corless is currently completing her Ph.D. in organic chemistry with Prof. Andrei Yudin at The University of Toronto. Her research is centred on the synthesis of kinetically amphoteric molecules, which offer a versatile platform for the development of chemoselective transformations with particular emphasis on creating novel biologically active molecules.

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Tagetitoxin – real structure finally revealed?

For centuries, natural products have been linked to medicine through traditional remedies and since played an important role in drug discovery.

New structure of tagetitoxin

New tagetitoxin structure based on 2D NMR correlations

Despite competition from other drug discovery methods, natural products have provided their fair share of clinical candidates and commercial drugs. Furthermore, the isolation, synthesis and biological evaluation of natural products often lead to lasting impressions in science.

In a recent study lead by Dr Abil Aleiv of the University College London, the structure of the known natural product tagetitoxin has been revised based on a detailed analysis of newly acquired NMR and MS data. The group employed 2D 1H–13C HMBC correlations and long-range JCH couplings in conjunction with computational analysis to correlate JCH couplings with predicted values.

For several years, the structure of tagetitoxin remained a mystery. First identified in 1981 by Mitchell, the structure was only partially characterized by MS and was proposed to be an 8-membered heteroatomic ring.  Revised structures have since been published by Mitchel (1989), Vassylyev (2005) and Gronwald (2005). Despite all these efforts, conflicting results and incomplete analyses resulted in the absolute configuration remaining undetermined.

Structures of tagetitoxin previously published by Mitchel (1989), Vassylyev (2005) and Gronwald (2005)

Early analysis of complex structures was generally difficult as spectrometers were relatively insensitive and experiments were performed at low-fields strengths. Through the increasing prevalence and utility of modern 2D NMR experiments in the past decade, NMR has become a powerful and enabling tool for structure elucidation and confirmation.

In addition, the key to Dr Aliev’s findings lies in confirming the purity of the tagetitoxin sample the group had acquired. They noted that the compound gradually decomposed in aqueous solutions if left for prolonged periods of time, which they suspect led to additional peaks being observed in previously reported NMR spectra.

This exciting work showcases the importance of technical advances in determining the structure of biologically active natural products with greater ease and confidence. As a result, advances in lead development and the identification of important families of pharmacophores for drug discovery can be attained with greater efficiency, which may contribute to a revival of interest in natural products for drug discovery purposes.

To find out more see:

The structure of tagetitoxin
Abil E. Aliev, Kersti Karu, Robin E. Mitchell and Michael J. Porter
DOI: 10.1039/c5ob02076j


Victoria Corless is currently completing her Ph.D. in organic chemistry with Prof. Andrei Yudin at The University of Toronto. Her research is centred on the synthesis of kinetically amphoteric molecules, which offer a versatile platform for the development of chemoselective transformations with particular emphasis on creating novel biologically active molecules.

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Entry into Mitochondria to reveal oxidative secrets

Recently, researchers from The University of Sydney, under the leadership of Dr. Elizabeth New, have reported a novel redox probe that selectively localises in Mitochondria. This fluorescent probe, NpFR2, has been used to identify the variations in the oxidative capacity of the haematopoietic cells.

Targeting Mitochondria has become one of the most important research protocols due to its immense importance to organelle-specific drug delivery. Mitochondria, being the power house of a cell, are the focus of researchers working in the area. Similarly, reactive oxygen species (ROS) have a key role and their levels are important in maintaining the redox homeostasis of the cell. A number of biological processes have been linked to mitochondrial ROS levels. These include response to hypoxia, immune responses, cellular differentiation and maturation, autophagy and ageing.

Graphic 1Graphic 2

In this paper, Dr. Elizabeth New et al., presents this novel compound that can be used reversibly and has a reduction potential within the biologically relevant range. To target mitochondria, a triphenyl phosphonium (TPP) group is been incorporated into the molecule. Further, they test this molecule in haematopoietic cells and can identify the mitochondrial ROS levels of different types of cells such as bone marrow macrophages, thymus and spleen.

NpFR2 can further be combined with other fluorescent probes and antibodies for further understanding of mitochondrial ROS in different cell processes.

Find out more in their Communication:

Mitochondrially targeted redox probe reveals the variations in oxidative capacity of the haematopoietic cells
Amandeep Kaur, Kurt W. L. Brigden, Timothy F. Cashman, Stuart T. Fraser and Elizabeth J. New
DOI: 10.1039/C5OB00928F

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HOT Organic & Biomolecular Chemistry articles

The following Organic & Biomolecular Chemistry articles have all been recommened by the reviewers of the articles as being particularly interesting or particularly significant research. These have all been made free to access until 20th April 2015. The order they appear in the list holds no special meaning or ranking.

Silver catalysed decarboxylative alkylation and acylation of pyrimidines in aqueous media
Wen-Peng Mai, Bin Sun, Li-Qin You, Liang-Ru Yang, Pu Mao, Jin-Wei Yuan, Yong-Mei Xiao and Ling-Bo Qu
DOI: 10.1039/C4OB02524E

10.1039/C4OB02524E


Templating carbohydrate-functionalised polymer-scaffolded dynamic combinatorial libraries with lectins
Clare S. Mahon, Martin A. Fascione, Chadamas Sakonsinsiri, Tom E. McAllister, W. Bruce Turnbull and David A. Fulton
DOI: 10.1039/C4OB02587C

10.1039/C4OB02587C


Oxidative asymmetric umpolung alkylation of Evans’ β-ketoimides using dialkylzinc nucleophiles
Tom A. Targel, Jayprakash N. Kumar, O. Svetlana Shneider, Sukanta Bar, Natalia Fridman, Shimon Maximenko and Alex M. Szpilman
DOI: 10.1039/C4OB02601B

10.1039/C4OB02601B


Cyclopropanation using flow-generated diazo compounds
Nuria M. Roda, Duc N. Tran, Claudio Battilocchio, Ricardo Labes, Richard J. Ingham, Joel M. Hawkins and Steven V. Ley
DOI: 10.1039/C5OB00019J, Communication

10.1039/C5OB00019J


Supramolecular control of transition metal complexes in water by a hydrophobic cavity: a bio-inspired strategy
Olivia Bistri and Olivia Reinaud
DOI: 10.1039/C4OB02511C

10.1039/C4OB02511C


Cyclopenta[b]naphthalene cyanoacrylate dyes: synthesis and evaluation as fluorescent molecular rotors
Laura S. Kocsis, Kristyna M. Elbel, Billie A. Hardigree, Kay M. Brummond, Mark A. Haidekker and Emmanuel A. Theodorakis
DOI: 10.1039/C4OB02563F

10.1039/C4OB02563F


Chiral nanostructuring of multivalent macrocycles in solution and on surfaces
Marco Caricato, Arnaud Delforge, Davide Bonifazi, Daniele Dondi, Andrea Mazzanti and Dario Pasini
DOI: 10.1039/C4OB02643H

10.1039/C4OB02643H


Physicochemical studies on the copper(II) binding by glycated collagen telopeptides
Meder Kamalov, Paul W. R. Harris, Christian G. Hartinger, Gordon M. Miskelly, Garth J. S. Cooper and Margaret A. Brimble
DOI: 10.1039/C4OB02536A
Regiodivergent Lewis base-promoted O- to C-carboxyl transfer of furanyl carbonates
Craig D. Campbell, Caroline Joannesse, Louis C. Morrill, Douglas Philp and Andrew D. Smith
DOI: 10.1039/C4OB02629B

10.1039/C4OB02536A


Total syntheses of five uvacalols: structural validation of uvacalol A, uvacalol B and uvacalol C and disproval of the structures of uvacalol E and uvacalol G
Adiyala Vidyasagar and Kana M. Sureshan
10.1039/C4OB0266310.1039/C4OB02663B B


Direct biosynthetic cyclization of a distorted paracyclophane highlighted by double isotopic labelling of L-tyrosine
Alexandre Ear, Séverine Amand, Florent Blanchard, Alain Blond, Lionel Dubost, Didier Buisson and Bastien Nay
DOI: 10.1039/C5OB00114E

10.1039/C5OB00114E


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HOT Organic & Biomolecular Chemistry articles

The following Organic & Biomolecular Chemistry articles have all been recommened by the reviewers of the articles as being particularly interesting or particularly significant research. These have all been made free to access until 16th March 2015. The order they appear in the list holds no special meaning or ranking.

E. coli cells expressing the Baeyer–Villiger monooxygenase ‘MO14’ (ro03437) from Rhodococcus jostii RHA1 catalyse the gram-scale resolution of a bicyclic ketone in a fermentor
Benjamin D. Summers, Muhiadin Omar, Thomas O. Ronson, Jared Cartwright, Michael Lloyd and Gideon Grogan
DOI: 10.1039/C4OB01441C, Paper
From themed collection In Celebration of Richard Taylor’s 65th Birthday

C4OB01441C GA


Synthesis of unsaturated phosphatidylinositol 4-phosphates and the effects of substrate unsaturation on SopB phosphatase activity
Samuel Furse, LokHang Mak, Edward W. Tate, Richard H. Templer, Oscar Ces, Rüdiger Woscholski and Piers R. J. Gaffney
DOI: 10.1039/C4OB02258K, Paper

C4OB02258K GA


A microwave-assisted multicomponent synthesis of substituted 3,4-dihydroquinazolinones
Marc Y. Stevens, Krzysztof Wieckowski, Peng Wu, Rajiv T. Sawant and Luke R. Odell
DOI: 10.1039/C4OB02417F, Paper

C4OB02417F GA


Near-instant surface-selective fluorogenic protein quantification using sulfonated triarylmethane dyes and fluorogen activating proteins
Qi Yan, Brigitte F. Schmidt, Lydia A. Perkins, Matharishwan Naganbabu, Saumya Saurabh, Susan K. Andreko and Marcel P. Bruchez
DOI: 10.1039/C4OB02309A, Paper

C4OB02309A GA


Bacterial patterning controlled by light exposure
Willem A. Velema, Jan Pieter van der Berg, Wiktor Szymanski, Arnold J. M. Driessen and Ben L. Feringa
DOI: 10.1039/C4OB02483D, Communication

C4OB02483D GA


Exploring the scope of the isothiourea-mediated synthesis of dihydropyridinones
Pei-Pei Yeh, David S. B. Daniels, Charlene Fallan, Eoin Gould, Carmen Simal, James E. Taylor, Alexandra M. Z. Slawin and Andrew D. Smith
DOI: 10.1039/C4OB02408G, Paper

C4OB02408G GA


Energy transfer between amphiphilic porphyrin polymer shells and upconverting nanoparticle cores in water-dispersible nano-assemblies
T. Wu, S. Kaur and N. R. Branda
DOI: 10.1039/C4OB02401J, Paper

C4OB02401J GA


Copper-catalyzed oxidative alkenylation of thioethers via Csp3–H functionalization
Hao Cao, Dong Liu, Chao Liu, Xinquan Hu and Aiwen Lei
DOI: 10.1039/C4OB02564D, Communication

C4OB02564D GA


Volatiles from nineteen recently genome sequenced actinomycetes
Christian A. Citron, Lena Barra, Joachim Wink and Jeroen S. Dickschat
DOI: 10.1039/C4OB02609H, Paper

C4OB02609H GA


Functional chromatographic technique for natural product isolation
Eric C. Lau, Damian J. Mason, Nicole Eichhorst, Pearce Engelder, Celestina Mesa, E. M. Kithsiri Wijeratne, G. M. Kamal B. Gunaherath, A. A. Leslie Gunatilaka, James J. La Clair and Eli Chapman
DOI: 10.1039/C4OB02292K, Communication

C4OB02292K GA

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HOT Organic & Biomolecular Chemistry articles

The following Organic & Biomolecular Chemistry articles have all been recommened by the reviewers of the articles as being particularly interesting or particularly significant research. These have all been made free to access until 15th February 2015. The order they appear in the list holds no special meaning or ranking.

Cationic azacryptands as selective three-way DNA junction binding agents
Jana Novotna, Aurelien Laguerre, Anton Granzhan, Marc Pirrotta, Marie-Paule Teulade-Fichou and David Monchaud 
DOI: 10.1039/C4OB01846J, Paper

C4OB01846J GA


Efficient merging of copper and photoredox catalysis for the asymmetric cross-dehydrogenative-coupling of alkynes and tetrahydroisoquinolines
Inna Perepichka, Soumen Kundu, Zoë Hearne and Chao-Jun Li 
DOI: 10.1039/C4OB02138J, Paper

C4OB02138J GA


A peptide topological template for the dispersion of [60]fullerene in water
S. Bartocci, D. Mazzier, A. Moretto and M. Mba 
DOI: 10.1039/C4OB02102A, Communication
From themed collection Supramolecular Chemistry in Water

C4OB02102A GA


6-Substituted 1,2-benzoxathiine-2,2-dioxides are isoform-selective inhibitors of human carbonic anhydrases IX, XII and VA
Muhammet Tanc, Fabrizio Carta, Andrea Scozzafava and Claudiu T. Supuran 
DOI: 10.1039/C4OB02155J, Communication

C4OB02155J GA


Artificial metalloenzymes for the diastereoselective reduction of NAD+ to NAD2H
Tommaso Quinto, Daniel Häussinger, Valentin Köhler and Thomas R. Ward 
DOI: 10.1039/C4OB02071E, Communication
From themed collection Supramolecular Chemistry in Water

C4OB02071E GA

 


Design and synthesis of fluorescent 7-deazaadenosine nucleosides containing π-extended diarylacetylene motifs
Sara De Ornellas, John M. Slattery, Robert M. Edkins, Andrew Beeby, Christoph G. Baumann and Ian J. S. Fairlamb 
DOI: 10.1039/C4OB02081B, Communication

C4OB02081B GA


One-pot quadruple/triple reaction sequence: a useful tool for the synthesis of natural products
K. Kashinath and D. Srinivasa Reddy 
DOI: 10.1039/C4OB02143F, Perspective

C4OB02143F GA


 

Indole-based novel small molecules for the modulation of bacterial signalling pathways
Nripendra Nath Biswas, Samuel K. Kutty, Nicolas Barraud, George M. Iskander, Renate Griffith, Scott A. Rice, Mark Willcox, David StC. Black and Naresh Kumar 
DOI: 10.1039/C4OB02096K, Paper

C4OB02096K GA


Carbocycles from donor–acceptor cyclopropanes
Huck K. Grover, Michael R. Emmett and Michael A. Kerr 
DOI: 10.1039/C4OB02117G, Review Article

C4OB02117G GA


Synthesis of isoxazolidine-containing uridine derivatives as caprazamycin analogues
Mayumi Yamaguchi, Akira Matsuda and Satoshi Ichikawa 
DOI: 10.1039/C4OB02142H, Paper

C4OB02142H GA


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HOT Organic & Biomolecular Chemistry articles

The following Organic & Biomolecular Chemistry articles have all been recommened by the reviewers of the articles as being particularly interesting or particularly significant research. These have all been made free to access until 31st December 2014. The order they appear in the list holds no special meaning or ranking.

Catalytic asymmetric desymmetrization approaches to enantioenriched cyclopentanes
Madhu Sudan Manna and Santanu Mukherjee 
DOI: 10.1039/C4OB01649A, Perspective

C4OB01649A GA


Corrin-based chemosensors for the ASSURED detection of endogenous cyanide
Felix Zelder and Lucas Tivana 
DOI: 10.1039/C4OB01889C, Perspective


An efficient synthetic route to 1,3-bis(arylethynyl)isobenzofuran using alkoxybenzocyclobutenone as a reactive platform
Kenta Asahina, Suguru Matsuoka, Ryosuke Nakayama and Toshiyuki Hamura 
DOI: 10.1039/C4OB02012J, Communication

C4OB02012J GA


Cationic azacryptands as selective three-way DNA junction binding agents
Jana Novotna, Aurelien Laguerre, Anton Granzhan, Marc Pirrotta, Marie-Paule Teulade-Fichou and David Monchaud 
DOI: 10.1039/C4OB01846J, Paper

C4OB01846J GA


An efficient reagent for covalent introduction of alkynes into proteins
Jie Zhang, Dejun Ma, Dawei Du, Zhen Xi and Long Yi 
DOI: 10.1039/C4OB01873G, Communication

C4OB01873G GA


Efficient merging of copper and photoredox catalysis for the asymmetric cross-dehydrogenative-coupling of alkynes and tetrahydroisoquinolines
Inna Perepichka, Soumen Kundu, Zoë Hearne and Chao-Jun Li 
DOI: 10.1039/C4OB02138J, Paper

C4OB02138J GA


Naphthalene diimides as red fluorescent pH sensors for functional cell imaging
Filippo Doria, Marco Folini, Vincenzo Grande, Graziella Cimino-Reale, Nadia Zaffaroni and Mauro Freccero 
DOI: 10.1039/C4OB02054E, Paper

C4OB02054E GA

A peptide topological template for the dispersion of [60]fullerene in water
S. Bartocci, D. Mazzier, A. Moretto and M. Mba 
DOI: 10.1039/C4OB02102A, Communication
C4OB02102A GA

6-Substituted 1,2-benzoxathiine-2,2-dioxides are isoform-selective inhibitors of human carbonic anhydrases IX, XII and VA
Muhammet Tanc, Fabrizio Carta, Andrea Scozzafava and Claudiu T. Supuran 
DOI: 10.1039/C4OB02155J, Communication
C4OB02155J GA

The rapid synthesis of oxazolines and their heterogeneous oxidation to oxazoles under flow conditions
Steffen Glöckner, Duc N. Tran, Richard J. Ingham, Sabine Fenner, Zoe E. Wilson, Claudio Battilocchio and Steven V. Ley 
DOI: 10.1039/C4OB02105C, Paper
From themed collection Recent Advances in Flow Synthesis and Continuous Processing
C4OB02105C GA
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A new reagent for click bioconjugation

A recent communication in Organic and Biomolecular Chemistry reports the synthesis of a new reagent for the introduction of alkynes into proteins; a key step for click bioconjugation. The new diazonium reagent was prepared in a one-pot synthesis from commercially available 4-ethynylaniline.

Having optimized bioconjugation in a tyrosine containing small molecule, the new diazonium reagent was then used to covalently label proteins. Fluorescence labelling of protein surface tyrosine residues was achieved under mild conditions (pH 8.0) by reaction of the protein with the diazonium reagent and subsequent reaction with an azide-containing fluorescent compound. The new diazonium reagent was also used to achieve protein PEGylation; a strategy that could be employed to improve protein stability and reduce immunogenicity.

The new diazonium reagent can facilitate bioconjugation in a range of proteins and could be a useful addition to the biochemist’s toolbox.

Read the full article:
An efficient reagent for covalent introduction of alkynes into proteins
Jie Zhang, Dejun Ma, Dawei Du, Zhen Xi and Long Yi
Org. Biomol. Chem., 2014, DOI: 10.1039/C4OB01873G

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HOT Organic & Biomolecular Chemistry articles

The following Organic & Biomolecular Chemistry articles have all been recommened by the reviewers of the articles as being particularly interesting or particularly significant research. These have all been made free to access until 30th November. The order they appear in the list holds no special meaning or ranking.

Design strategies for bioorthogonal smart probes
Peyton Shieh and Carolyn R. Bertozzi
DOI: 10.1039/C4OB01632G, Review Article

bioorthogonal smart probes


Stereoselective intermolecular [2 + 2]-photocycloaddition reactions of maleic anhydride: stereocontrolled and regiocontrolled access to 1,2,3-trifunctionalized cyclobutanes
Florian Hernvann, Gloria Rasore, Valérie Declerck and David J. Aitken
DOI: 10.1039/C4OB01383B, Paper

Stereoselective intermolecular [2 + 2]-photocycloaddition reactions of maleic anhydride


Towards novel efficient and stable nuclear import signals: synthesis and properties of trimethylguanosine cap analogs modified within the 5′,5′-triphosphate bridge
Malgorzata Zytek, Joanna Kowalska, Maciej Lukaszewicz, Blazej A. Wojtczak, Joanna Zuberek, Aleksandra Ferenc-Mrozek, Edward Darzynkiewicz, Anna Niedzwiecka and Jacek Jemielity
DOI: 10.1039/C4OB01579G, Paper

trimethylguanosine cap analogs


Catalytic asymmetric synthesis of the pentacyclic core of (−)-nakadomarin A via oxazolidine as an iminium cation equivalent
Nobuya Tsuji, Michael Stadler, Naoya Kazumi, Tsubasa Inokuma, Yusuke Kobayashi and Yoshiji Takemoto
DOI: 10.1039/C4OB01678E, Communication

atalytic asymmetric synthesis of the pentacyclic core of (−)-nakadomarin A


Short and efficient synthesis of fluorinated δ-lactams
Thomas J. Cogswell, Craig S. Donald, De-Liang Long and Rodolfo Marquez
DOI: 10.1039/C4OB01547A, Paper

synthesis of fluorinated δ-lactams


An efficient route to synthesize isatins by metal-free, iodine-catalyzed sequential C(sp3)–H oxidation and intramolecular C–N bond formation of 2′-aminoacetophenones
Venkatachalam Rajeshkumar, Selvaraj Chandrasekar and Govindasamy Sekar
DOI: 10.1039/C4OB01564A, Paper

 I2-catalyzed synthesis of isatins


5-Nitroindole oligonucleotides with alkynyl side chains: universal base pairing, triple bond hydration and properties of pyrene “click” adducts
Sachin A. Ingale, Peter Leonard, Haozhe Yang and Frank Seela
DOI: 10.1039/C4OB01478B, Paper

5-Nitroindole oligonucleotides with alkynyl side chains


Cross-strand histidine–aromatic interactions enhance acyl-transfer rates in beta-hairpin peptide catalysts
M. Matsumoto, S. J. Lee, M. R. Gagné and M. L. Waters
DOI: 10.1039/C4OB01754D, Paper

 Cross-strand histidine–aromatic interactions enhance acyl-transfer rates in beta-hairpin peptide catalysts


The asymmetric syntheses of pyrrolizidines, indolizidines and quinolizidines via two sequential tandem ring-closure/N-debenzylation processes
Stephen G. Davies, Ai M. Fletcher, Emma M. Foster, Ian T. T. Houlsby, Paul M. Roberts, Thomas M. Schofield and James E. Thomson
DOI: 10.1039/C4OB01737D, Paper

asymmetric syntheses of pyrrolizidines, indolizidines and quinolizidines


Organocatalytic Michael addition–lactonisation of carboxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents
Louis C. Morrill, Daniel G. Stark, James E. Taylor, Siobhan R. Smith, James A. Squires, Agathe C. A. D’Hollander, Carmen Simal, Peter Shapland, Timothy J. C. O’Riordan and Andrew D. Smith
DOI: 10.1039/C4OB01788A, Paper

Organocatalytic Michael addition–lactonisation of carboxylic acids

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