Archive for April, 2011

Top ten most accessed articles in March

This month sees the following articles in OBC that are in the top ten most accessed:-

A facile method for the synthesis of oxindole based quaternary a-aminonitriles via the Strecker reactionÂ
Yun-Lin Liu, Feng Zhou, Jun-Jie Cao, Cong-Bin Ji, Miao Ding and Jian ZhouÂ
Org. Biomol. Chem., 2010, 8, 3847-3850 DOI: 10.1039/C0OB00174K, Communication 

Sequential one-pot combination of multi-component and multi-catalysis cascade reactions: an emerging technology in organic synthesisÂ
Dhevalapally B. Ramachary and Sangeeta JainÂ
Org. Biomol. Chem., 2011, 9, 1277-1300 DOI: 10.1039/C0OB00611D, Emerging Area 

Carbohydrate chemistry in drug discovery 
M. Carmen Galan, David Benito-Alifonso and Gregory M. WattÂ
Org. Biomol. Chem., 2011, 9, 3598-3610 DOI: 10.1039/C0OB01017K, PerspectiveÂ

Mannich-Michael versus formal aza-Diels-Alder approaches to piperidine derivativesÂ
P. Ricardo Girling, Takao Kiyoi and Andrew WhitingÂ
Org. Biomol. Chem., 2011, 9, 3105-3121 DOI: 10.1039/C0OB00996B, PerspectiveÂ

A general approach to high-yielding asymmetric synthesis of chiral 3-alkyl-4-nitromethylchromans via cascade Barbas-Michael and acetalization reactionsÂ
Dhevalapally B. Ramachary, M. Shiva Prasad and R. MadhavacharyÂ
Org. Biomol. Chem., 2011, 9, 2715-2721 DOI: 10.1039/C0OB00861C, Paper 

A ratiometric near-infrared pH-responsive fluorescent dye based on distyryl BODIPYÂ
Hui He and Dennis K. P. NgÂ
Org. Biomol. Chem., 2011, 9, 2610-2613 DOI: 10.1039/C0OB01252A, CommunicationÂ

Cycloaddition of homochiral dihydroimidazoles: A 1,3-dipolar cycloaddition route to optically active pyrrolo[1,2-a]imidazolesÂ
Raymond C. F. Jones, Kevin J. Howard, John S. Snaith, Alexander J. Blake, Wang-Shei Li and Peter J. SteelÂ
Org. Biomol. Chem., 2011, 9, 297-306 DOI: 10.1039/C0OB00529K, PaperÂ

Rhodamine-based highly sensitive colorimetric off-on fluorescent chemosensor for Hg2+ in aqueous solution and for live cell imagingÂ
Hengguo Wang, Yapeng Li, Shufei Xu, Yanchun Li, Chen Zhou, Xiaoliang Fei, Lei Sun, Chaoqun Zhang, Yaoxian Li, Qingbiao Yang and Xiaoyi XuÂ
Org. Biomol. Chem., 2011, 9, 2850-2855 DOI: 10.1039/C0OB01032D, PaperÂ

Chiral BINOL-derived phosphoric acids: privileged Brønsted acid organocatalysts for C-C bond formation reactionsÂ
Alexandru Zamfir, Sebastian Schenker, Matthias Freund and Svetlana B. TsogoevaÂ
Org. Biomol. Chem., 2010, 8, 5262-5276 DOI: 10.1039/C0OB00209G, PerspectiveÂ

Second-order NMR spectra at high field of common organic functional groupsÂ
Paul J. StevensonÂ
Org. Biomol. Chem., 2011, 9, 2078-2084 DOI: 10.1039/C0OB00705F, CommentÂ

Why not take a look at the articles today and blog your thoughts and comments below.

Fancy submitting an article to OBC? Then why not submit to us today or alternatively email us your suggestions.

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Effect of substituents on the stabilities of radicals-OBC Cover Issue 10

Leo Radom and collaborators in Australia and Switzerland present in this paper a thorough computational study, which correlates with experimental data, of the stability of a very large series of multiply-substituted carbon-centered radicals. They look at the stabilization and interaction energies and the deviations from additivity of RSEs.

The cover image depicts how the stabilities of multiply-substituted carbon-centered radicals are compared with the stabilities of their monosubstituted components. The factors that influence the effect of substituents on such a comparison are discussed.

This article will be included in the OBC special issue in memory of Athel Beckwith: Free Radical Chemistry. Coming soon.

Effect of substituents on the stabilities of multiply-substituted carbon-centered radicals
Ambili S. Menon, David J. Henry, Thomas Bally and Leo Radom
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C1OB05196B

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HOT: Radical route to lactams

Lactams are often used as building blocks for antibiotics, such as penicillin. Now Hiroshi Matsubara, Ilhyong Ryu and colleagues have investigated an exciting radical route to produce them.

They show that acyl radicals can react as electrophiles in ionic type addition reactions with amines, which leads to cyclisation forming a series of lactams. Depending on the N-substituent (good or not good leaving group) reaction occurs via rare 1,4-H shift or via a formal homolytic substitution at nitrogen leading to interesting new compounds.

Download the paper now to read more about the synthetic scope and theoretical findings. It is free to access until 25th May.   

This article will be included in the OBC special issue in memory of Athel Beckwith: Free Radical Chemistry. Coming soon

Radical carbonylation of ω-alkynylamines leading to α-methylene lactams. Synthetic scope and the mechanistic insights
Ilhyong Ryu, Takahide Fukuyama, Mami Tojino, Yoshitaka Uenoyama, Yuka Yonamine, Nozomi Terasoma and Hiroshi Matsubara
Org. Biomol. Chem., 2011, 9, 3780-3786
DOI: 10.1039/C1OB05145H

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Review: Carbohydrate chemistry in drug discovery

Carbohydrates are the most diverse and one of the most important classes of biomolecules in nature. However, it is still difficult to find carbohydrate-based drugs in the market nowadays. The high polarity of this kind of drugs represents an issue for the pharmacological properties. Therefore, understanding and being able to modify these properties would help with the development of more ‘drug-like’ carbohydrate-based drugs.

In this review, M Carmen Galan and co-workers at University of Bristol, give and up-date on the latest advancements in carbohydrate chemistry and the role thy play in drug discovery.

If you want to find out more, download it now.

Carbohydrate chemistry in drug discovery
M. Carmen Galan, David Benito-Alifonso and Gregory M. Watt
Org. Biomol. Chem., 2011, 9, 3598-3610
DOI: 10.1039/C0OB01017K

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Emerging area: unlocked nucleic acids

The continuing search for modified nucleic acids with improved properties for use in molecular diagnostics, gene- and RNA-targeting therapies has now lighted on unlocked nucleic acids monomers – which act as acyclic RNA mimics.  Unlocked nucleic acids monomers (UNA) were first synthesised over a decade ago, but only now has their potential for therapeutics really been explored.

Structure of a UNA monomer

In this Emerging Area article, Anna Pasternak and Jesper Wengel (University of Southern Denmark) find that UNA monomers inserted into oligonucleotides can modulate the thermodynamic stability of DNA and RNA structures such as duplexes, quadruplexes and i-motifs.  This, they hope, will open up new options for designing new quadruplex-based aptamer drugs and superior siRNA constructs due to their high silencing activity and low toxicity.

Download the article to read the full details:

Unlocked nucleic acid – an RNA modification with broad potential
Anna Pasternak and Jesper Wengel
Org. Biomol. Chem., 2011, 9, 3591-3597
DOI: 10.1039/C0OB01085E

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HOT: Switch on the rotaxane!

Rotaxanes are mechanically interlocked molecules with interesting physical and chemical properties. They have attracted much attention due to their potential applications in molecular electronics, smart materials and molecular machines.

In this HOT paper, Da-Hui Qu, He Tian and their research group at East China University of Science & Technology in Shanghai, synthesise a multi-state [2]rotaxane based on a crown ether. They introduce a dithienylethene (DTE) photochromic functional group that can be switched by pH, light or the combination of pH and light. This photochromic unit is responsible of the multi-mode alteration of intercomponent interactions such as energy transfer, electron transfer and charge transfer interactions.

This multi-state molecular shuttle has potential to construct multi-level molecular machines.

You can now read this article, which is free to download until 25th May, here.

The referees and the editorial office found it very interesting. We hope you like it too.

Altering intercomponent interactions in a photochromic multi-state [2]rotaxane
Hui Zhang, Xin-Xin Kou, Qiong Zhang, Da-Hui Qu and He Tian
Org. Biomol. Chem., 2011
DOI: 10.1039/C1OB05307H

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HOT article: upping the TEMPO-H

The stable radical TEMPO is an an important molecule for organic catalysis, and its protonated cousin TEMPO-H is an excellent chemical source of hydrogen.  However, Jason Masuda and Jason Clyburne (Saint Mary’s University, Canada) were concerned that, due to the current synthetic route, water present in TEMPO-H could lead to unwanted side reactions.

In this HOT paper they overcome this problem by reporting the first anhydrous route to TEMPO-H (2,2,6,6-tetramethylpiperidin-1-ol), by treating the sodium salt of TEMPO with triethylamine hydrochloride.  They show that the anhydrous form is not only more stable during synthesis, but that it has a different structure and reactivity patterns as well.  They tested their anhydrous compound against several molecules with low valence carbon centres such as carbenes and ketenes, demonstrating the use of the anhydrous form in avoiding side reactions and creating different complex structures.

Preparation of anhydrous TEMPO-H

You can read the full details of the synthesis and characterisation for free until 14th May:

Anhydrous TEMPO-H: reactions of a good hydrogen atom donor with low-valent carbon centres
Nick A. Giffin, Miller Makramalla, Arthur D. Hendsbee, Katherine N. Robertson, Cody Sherren, Cory C. Pye, Jason D. Masuda and Jason A. C. Clyburne
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C0OB00999G, Paper

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HOT: Novel efficient synthesis of functionalised naphthoquinones

Naphthoquinone derivatives have important pharmacological properties. They have been explored for their anti-inflammatory, antifungal and antitumor biological activities amongst many others. Therefore, efficient syntheses of naphthoquinines are of great interest.

In this paper, Jian Wang and his team at the National University of Singapore, have developed a new catalytic synthetic method for the preparation of chiral naphthoquinones with a novel chiral thiourea catalyst. They achieve excellent yields (94-99%) and excellent enantioselectivities (90-98% ee)

Read more about this new and very efficient synthesis in this HOT paper which is free to access until 14th May.

Enantioselective organocatalytic Michael-hemiketalization catalyzed by a trans-bifunctional indane thiourea catalyst
Yaojun Gao, Qiao Ren, Swee-Meng Ang and Jian Wang
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C1OB05404J

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OBC web theme: Foldamer Chemistry – call for papers

OBC is delighted to announce a high-profile web theme focussing on foldamer chemistry. Submissions are now open.

This online theme issue will be published at the end of 2011. Submissions of communications and full papers can be made at any time but must be received by the editorial office by 15 August 2011 for peer review.

Submission and tracking of manuscripts can be done directly online at http://mc.manuscriptcentral.com/ob. Submissions should indicate in the “comments to the editor” section that they are for the foldamers web theme.

You can view other, recently published OBC web themes at http://pubs.rsc.org/en/journals/journalissues/ob#!themedissues

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Review: Mannich–Michael vs. aza-Diels–Alder approaches to piperidine derivatives

Andrew Whiting and colleagues at University of Durham and Merck Research Laboratories, question whether the mechanism of the aza-Diels–Alder reaction is step wise as opposed to concerted when using
oxygenated dienes.

This review explain the mechanistic details as well as scope of the reaction in future.

Mannich–Michael versus formal aza-Diels–Alder approaches to piperidine derivatives
P. Ricardo Girling, Takao Kiyoi and Andrew Whiting
Org. Biomol. Chem., 2011, 9, 3105-3121
DOI: 10.1039/C0OB00996B

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