Archive for the ‘Hot articles’ Category

HOT Organic & Biomolecular Chemistry articles for November

Synthesis and fluorescence characteristics of ATP-based FRET probes
Norman Hardt, Stephan M. Hacker and Andreas Marx
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41751D

Free to access until 26th December

Synthesis and fluorescence characteristics of ATP-based FRET probes


Aromatic character and relative stability of neo-confused porphyrin tautomers and related compounds
Deyaa I. AbuSalim and Timothy D. Lash
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB42063A

Free to access until 26th December

Aromatic character and relative stability of neo-confused porphyrin tautomers and related compounds


There is no universal mechanism for the cleavage of RNA model compounds in the presence of metal ion catalysts
Heidi Korhonen, Timo Koivusalo, Suvi Toivola and Satu Mikkola
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41554F

Free to access until 26th December

There is no universal mechanism for the cleavage of RNA model compounds in the presence of metal ion catalysts

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Monitoring ATP cleavage by fluorescence

Exploring enzymatic systems that use adenosine triphosphate (ATP) can improve our understanding of various biological pathways. The production of ATP cleavage products can be monitored in vitro using radioactive ATP analogues or by the colorimetric detection of released phosphate or pyrophosphate. These methods do not allow the continuous detection of ATP turnover. Enzyme-coupled assays offer an alternative means to explore these systems, but require consideration of the effects of additional enzymes. Thus, there is a need for probes that enable the continuous study of enzymatic ATP consumption.

This HOT article describes the synthesis of ATP analogues labelled with a fluorescence donor and a fluorescence acceptor, suitable for Förster Resonance Energy Transfer. Excitation promotes energy transfer from the fluorescence donor to the fluorescence acceptor on the same molecule. Cleavage of the ATP analogue prevents energy transfer via an intramolecular pathway, resulting in a large change in fluorescence. Synthetic routes to seven new doubly labelled ATP analogues are reported and the fluorescence properties of these molecules are described using snake venom phosphodiesterase as a model enzyme.

Synthesis and fluorescence characteristics of ATP-based FRET probes
Norman Hardt, Stephan M. Hacker and Andreas Marx
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41751D

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HOT Organic & Biomolecular Chemistry articles for October

The development of highly active acyclic chiral hydrazides for asymmetric iminium ion organocatalysis
Eoin Gould, Tomas Lebl, Alexandra M. Z. Slawin, Mark Reid, Tony Davies and Andrew D. Smith
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41719K, Paper

Free to access until 2nd December


Efficient and regioselective nickel-catalyzed [2 + 2 + 2] cyclotrimerization of ynoates and related alkynes
Sanjeewa K. Rodrigo, Israel V. Powell, Michael G. Coleman, Jeanette A. Krause and Hairong Guan
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41872C, Communication

Free to access until 25th November


Characterization of CYP76AH4 clarifies phenolic diterpenoid biosynthesis in the Lamiaceae
Jiachen Zi and Reuben J. Peters
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41885E, Communication

Free to access until 25th November


The Cope rearrangement of gem-dimethyl substituted divinylcyclopropanes
Jonathan D. Osler, William P. Unsworth and Richard J. K. Taylor
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41617H, Paper

Free to access until 18th November

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Novel synthetic anion transporters

Acylthioureas as anion transporters: the effect of intramolecular hydrogen bonding

Acylthioureas that can act as ion transporters across cell membranes may lead to novel treatments for cystic fibrosis and associated conditions.

Inorganic anions such as chloride play a crucial role in biological systems, and the mechanisms behind their transport and regulation are still to be fully understood. Proteins embedded in the lipid bilayer regulate these transport processes and carry anions across cell membranes. When these processes are defective, then channelopathic diseases such as cystic fibrosis can develop.

Synthetic anion transporters based on small molecules may serve as replacements for faulty transport proteins, and may therefore find use in the treatment of such diseases.

Professor Philip Gale and his research group at the University of Southampton have been looking into synthetic membrane transporters for anions based on thiourea scaffolds.

In this HOT Article, Prof. Gale and co-workers discuss the synthesis of a series of acylthioureas and their potential as anion transporters in POPC lipid bilayers. They have discovered that these molecules function effectively as anion antiporters, but that the incorporation of lipophilic moieties leads to a reduction in their efficiency. This is due to an intramolecular hydrogen bond that forms and shields the binding site from interactions with water.

It is clear from these results that striking a balance between hydro- and lipo-philicity of the anion transporter is of crucial consideration in their efficiency. Furthermore, the intramolecular hydrogen bonding behaviour of these molecules may be of use in enabling more hydrophilic moieties to be incorporated in future transporter design. It is hoped that this information will eventually lead to the development of new transporters for medicinal applications.

Acylthioureas as anion transporters: the effect of intramolecular hydrogen bonding
Cally J. E. Haynes, Nathalie Busschaert, Isabelle L. Kirby, Julie Herniman, Mark E. Light, Neil J. Wells, Igor Marques, Vítor Félix and Philip A. Gale
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41522H

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Gold nanoparticles detect avian influenza

The influenza virus is capable of crossing from animals to humans. The health threat posed by influenza jumping the species barrier has been highlighted by recent outbreaks: N5N1 ‘bird flu’ in 2003/2004, H1N1 ‘swine flu’ in 2009 and avian H7N9 earlier this year. Current methods used for the detection of influenza are time consuming and may require trained analysts and specialised equipment. There is a need for a rapid diagnostic test to discriminate between human influenza and emerging animal strains.

This HOT article describes a gold nanoparticle-based colorimetric assay for the detection of influenza. Specificity was achieved by targeting the haemagglutanin (HA) surface glycoprotein.  Human influenza binds preferentially to sialic acid α2,6 galactose sequences and avian influenza preferentially binds to sialic acid α2,3 galactose sequences. Gold nanoparticles were functionalised with trivalent α2,6-thio-linked sialic acid ligands and polyethylene glycol ligands. A solution of gold nanoparticles was used to detect HA virus surface glycoproteins and in the presence of human influenza virus a colour change was observed. The colour change was caused by the aggregation of the glycopeptide with the influenza virus and was detectable with the naked eye. Owing to the careful choice of ligands, this assay was able to discriminate between human and avian H5N1 influenza.

Glyconanoparticles for the plasmonic detection and discrimination between human and avian influenza virus
María J. Marín, Abdul Rashid, Martin Rejzek, Shirley A. Fairhurst, Stephen A. Wharton, Stephen R. Martin, John W. McCauley, Thomas Wileman, Robert A. Field and David A. Russell
Org. Biomol. Chem., 2013,11, 7101-7107
DOI: 10.1039/C3OB41703D

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HOT Organic & Biomolecular Chemistry articles for September

Disulfide bond reduction-triggered molecular hydrogels of folic acid–Taxol conjugates
Chengbiao Yang, Dongxia Li, Qianqi FengZhao, Lianyong Wang, Ling Wang and Zhimou Yang
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB40969D, Paper


The influence of G-quadruplex structure on DNA-based asymmetric catalysis using the G-quadruplex-bound cationic porphyrin TMPyP4·Cu
Michael Wilking and Ulrich Hennecke
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41366G, Paper


A highly active cyclometallated iridium catalyst for the hydrogenation of imines
Barbara Villa-Marcos, Weijun Tang, Xiaofeng Wu and Jianliang Xiao
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41150H, Paper


ω-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor
Eul-Soo Park, Joo-Young Dong and Jong-Shik Shin
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB40495A, Paper


Visible-light activatable organic CO-releasing molecules (PhotoCORMs) that simultaneously generate fluorophores
Ping Peng, Chaoming Wang, Zheng Shi, Valentine K. Johns, Liyuan Ma, Jeremiah Oyer, Alicja Copik, Robert Igarashi and Yi Liao
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41385C, Communication


The first asymmetric total synthesis of (+)-coriandrone A and B
Wenjing Wang, Jijun Xue, Tian Tian, Yingdong Jiao and Ying Li
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41497C, Communication


Convergent synthesis and cellular uptake of multivalent cell penetrating peptides derived from Tat, Antp, pVEC, TP10 and SAP
Gabriela A. Eggimann, Stefanie Buschor, Tamis Darbre and Jean-Louis Reymond
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41023D, Paper


Copper(II) chloride mediated (aza)oxindole synthesis by oxidative coupling of Csp2–H and Csp3–H centers: substrate scope and DFT study
Chandan Dey, Evgeny Larionov and E. Peter Kündig
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41254G, Paper


Histidine-functionalized water-soluble nanoparticles for biomimetic nucleophilic/general-base catalysis under acidic conditions
Geetika Chadha and Yan Zhao
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41485J, Paper


A one-pot coupling–addition–cyclocondensation sequence (CACS) to 2-substituted 3-acylpyrroles initiated by a copper-free alkynylation
Jan Nordmann and Thomas J. J. Müller
Org. Biomol. Chem., 2013, DOI: 10.1039/C3OB41269E, Paper

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HOT – Novel copper-mediated cyclisations leading to diverse heterocyclic structures

copper-mediated oxidative coupling
In this HOT paper, Peter Kündig’s research team have developed a new mode of copper-mediated oxidative coupling allowing access to racemic (aza)oxindole structure in an efficient and atom-economic fashion.

Oxindoles are useful structures in organic chemistry as they are found ubiquitously in nature. Molecules bearing this motif have a range of interesting biological properties and new methods of their construction are always useful to the organic chemist.

Peter Kündig and his team at the University of Geneva have been looking into the asymmetric synthesis of these structures, employing palladium-catalysed intramolecular α-arylations of amide substrates.[1] During these studies, they discovered a novel and efficient route to access racemic 3,3,-disubstituted oxindoles which employed a copper-mediated radical reaction.[2] This reaction has also been applied to the racemic synthesis of aza-oxindoles.[3]

In this excellent account from Prof. Kündig, this methodology has been further explored. The substrate scope has been expanded leading to a range of oxindoles bearing a variety of aromatic, hetero- aromatic, allyl and heteroatom substituents in the 3-position. The reaction was also successfully performed on a large scale, with excellent yield and regioselectivity. In addition to this, some nifty DFT and computational studies confirm the proposed mechanism and regioselectivity.

Read the full article here.

Copper(II) chloride mediated (aza)oxindole synthesis by oxidative coupling of Csp2–H and Csp3–H centers: substrate scope and DFT study
Chandan Dey, Evgeny Larionov and E. Peter Kündig
Org. Biomol. Chem., 2013,  DOI: 10.1039/c3ob41254g


[1] E. P. Kündig, T. M. Seidel, Y. X. Jia and G. Bernardinelli, Angew. Chem., Int. Ed., 2007, 46, 8484; Y. X. Jia, J. M. Hillgren, E. L. Watson, S. P. Marsden and E. P. Kündig, Chem. Commun., 2008, 4040.

[2] Y. X. Jia and E. P. Kündig, Angew. Chem., Int. Ed., 2009, 48, 1636.

[3] C. Dey and E. P. Kündig, Chem. Commun., 2012, 48, 3064.

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HOT Organic & Biomolecular Chemistry articles for August

Pd(0)-catalyzed benzylic arylation–oxidation of 4-methylquinazolines via sp3 C–H activation under air conditions
Dan Zhao, Min-Xue Zhu, Yue Wang, Qi Shen and Jian-Xin Li
Org. Biomol. Chem., 2013,11, 6246-6249
DOI: 10.1039/C3OB41488D, Communication 

  


Major mechanistic differences between the reactions of hydroxylamine with phosphate di- and tri-esters
Michelle Medeiros, Eduardo H. Wanderlind, José R. Mora, Raphaell Moreira, Anthony J. Kirby and Faruk Nome
Org. Biomol. Chem., 2013,11, 6272-6284
DOI: 10.1039/C3OB40988K, Paper
From themed collection In Celebration of Andrew D. Hamilton’s Career in Chemistry  

 


Novel synthesis of various orthogonally protected Cα-methyllysine analogues and biological evaluation of a Vapreotide analogue containing (S)-α-methyllysine
Souvik Banerjee, Walker J. Wiggins, Jessie L. Geoghegan, Catherine T. Anthony, Eugene A. Woltering and Douglas S. Masterson
Org. Biomol. Chem., 2013,11, 6307-6319
DOI: 10.1039/C3OB41282B, Paper


Synthesis of novel pyrazole-based heterocycles via a copper(II)-catalysed domino annulation
Márió Gyuris, László G. Puskás, Gábor K. Tóth and Iván Kanizsai
Org. Biomol. Chem., 2013,11, 6320-6327
DOI: 10.1039/C3OB41146J, Paper


Structure–activity studies of 4-phenyl-substituted 2′-benzoylpyridine thiosemicarbazones with potent and selective anti-tumour activity
Adeline Y. Lukmantara, Danuta S. Kalinowski, Naresh Kumar and Des R. Richardson
Org. Biomol. Chem., 2013,11, 6414-6425
DOI: 10.1039/C3OB41109E, Paper

 


Transport of macrocyclic compounds across phospholipid bilayers by umbrella-rotaxanes
Christine Chhun, Josée Richard-Daniel, Julie Kempf and Andreea R. Schmitzer
Org. Biomol. Chem., 2013, Advance Article
DOI: 10.1039/C3OB41209A, Paper

 


Bifunctional building blocks in the Ugi-azide condensation reaction: a general strategy toward exploration of new molecular diversity
Steven Gunawan and Christopher Hulme
Org. Biomol. Chem., 2013, Advance Article
DOI: 10.1039/C3OB40900G, Paper 

 


Comparative in vitro studies of MR imaging probes for metabotropic glutamate subtype-5 receptor targeting
Sven Gottschalk, Jörn Engelmann, Gabriele A. Rolla, Mauro Botta, David Parker and Anurag Mishra
Org. Biomol. Chem., 2013, Advance Article
DOI: 10.1039/C3OB41297K, Paper 

 


Synthesis and biological evaluation of non-isomerizable analogues of Ala-tRNAAla
Denia Mellal, Matthieu Fonvielle, Marco Santarem, Maryline Chemama, Yoann Schneider, Laura Iannazzo, Emmanuelle Braud, Michel Arthur and Mélanie Etheve-Quelquejeu
Org. Biomol. Chem., 2013, Advance Article
DOI: 10.1039/C3OB41206G, Paper 

 


First synthesis of antitumoral dasyscyphin B
Ali Akhaouzan, Antonio Fernández, Ahmed I. Mansour, Esteban Alvarez, Ali Haidöur, Ramón Alvarez-Manzaneda, Rachid Chahboun and Enrique Alvarez-Manzaneda
Org. Biomol. Chem., 2013, Advance Article
DOI: 10.1039/C3OB41290C, Paper                                          

Open Access  

 

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Tethered aldo/keto-acids/esters unlock new bis-hetrocyclic tetrazolo scaffolds

The classical Ugi multi-component reaction can be used to generate a peptidic-like molecule, with 4 points of diversification, from an aldehyde, an amine, an isocyanide and a carboxylic acid. In the Ugi-azide reaction, the carboxylic acid is replaced with trimethylsilyl azide, providing a convenient route to 1,5-disubstituted tetrazoles. This scaffold is a bioisostere for the cis-amide bond.

In the HOT article, Gunawan and Hulme report the use of Ugi-azide reactions to generate a series of different bis-hetrocyclic tetrazolo scaffolds, facilitated by variation of the linker group in the aldo/keto-acids/esters. These scaffolds may aid the development of new molecular probes for the investigation of peptidergic biological systems.

Bifunctional building blocks in the Ugi-azide condensation reaction: a general strategy toward exploration of new molecular diversity

Bifunctional building blocks in the Ugi-azide condensation reaction: a general strategy toward exploration of new molecular diversity
Steven Gunawan and Christopher Hulme
DOI: 10.1039/C3OB40900G

Free to access for 4 weeks

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Don’t underestimate the power of the dark side

Electrophilicity - the dark side of indole reactivity

In this PERSPECTIVE article, Marco Bandini presents an overview of indole electrophilicity, illustrated with a range of pertinent examples of this “dark-side” of indole reactivity.

Indoles are one of the most common heterocyclic motifs found in nature. These bicyclic arenes have had a profound impact on drug discovery, materials science, catalysis and many other areas of chemistry.

Professor Marco Bandini and his research group at the Università di Bologna specialise in indole “decoration” and the development of new methodology for the chemical manipulation of this functional group.

The indolyl core is, as Bandini explains, “spectacularly nucleophilic” and this accounts for a large proportion of the literature contributions. There is, however, also a relatively undeveloped side of their reactivity: “electrophilic” indoles.

While there are many examples of this type of reactivity, some of which date back to the 1960s, it remains in the shadow of the well-understood and established chemistry that explores the indole core’s innate nucleophilicity. The opportunities to expand the chemical portfolio of indole decoration, via nucleophilic substitutions and additions, are still largely unexplored.

The ubiquity of this core means that new ways to functionalise and manipulate indoles will always be a welcome addition to the organic chemist’s toolbox. As Bandini discusses, exploitation of the umpolung chemistry of these functional groups provides access to a wide diversity of chemical structures.

This Perspective article elegantly documents the electrophilic nature of indoles, and highlights some of the important discoveries and developments in this field. It is a must-read for anyone interested in these intriguing molecules.

Give yourself to the dark side and check out the article here.

Electrophilicity: the “dark-side” of indole chemistry
Marco Bandini
DOI: 10.1039/C3OB40735G

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