Chemical Science Blog

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

Total synthesis of diazonamide A 
Robert R. Knowles, Joseph Carpenter, Simon B. Blakey, Akio Kayano, Ian K. Mangion, Christopher J. Sinz and David W. C. MacMillan 
Chem. Sci., 2011, 2, 308-311, DOI: 10.1039/C0SC00577K, Edge Article 

Dialkylbiaryl phosphines in Pd-catalyzed amination: a user’s guide 
David S. Surry and Stephen L. Buchwald 
Chem. Sci., 2011, 2, 27-50, DOI: 10.1039/C0SC00331J, Perspective 

Nitrogen-directed ketone hydroacylation: Enantioselective synthesis of benzoxazecinones 
Hasan A. Khan, Kevin G. M. Kou and Vy M. Dong 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00469C, Edge Article 

Ru-catalyzed activation of sp3 C–O bonds: O- to N-alkyl migratory rearrangement in pyridines and related heterocycles  
Charles S. Yeung, Tom H. H. Hsieh and Vy M. Dong 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00498G, Edge Article 

Ir-catalyzed highly selective addition of pyridyl C-H bonds to aldehydes promoted by triethylsilane 
Bi-Jie Li and Zhang-Jie Shi 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00419G, Edge Article 

Palladium-catalyzed amination reactions in flow: overcoming the challenges of clogging via acoustic irradiation 
Timothy Noël, John R. Naber, Ryan L. Hartman, Jonathan P. McMullen, Klavs F. Jensen and Stephen L. Buchwald 
Chem. Sci., 2011, 2, 287-290, DOI: 10.1039/C0SC00524J, Edge Article 

Palladium-catalyzed coupling of functionalized primary and secondary amines with aryl and heteroaryl halides: two ligands suffice in most cases 
Debabrata Maiti, Brett P. Fors, Jaclyn L. Henderson, Yoshinori Nakamura and Stephen L. Buchwald 
Chem. Sci., 2011, 2, 57-68, DOI: 10.1039/C0SC00330A, Edge Article 

Sulfonated graphene as water-tolerant solid acid catalyst
Junyi Ji, Guanghui Zhang, Hongyu Chen, Shulan Wang, Guoliang Zhang, Fengbao Zhang and Xiaobin Fan 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00484G, Edge Article 

Mechanised materials 
Megan M. Boyle, Ronald A. Smaldone, Adam C. Whalley, Michael W. Ambrogio, Youssry Y. Botros and J. Fraser Stoddart 
Chem. Sci., 2011, 2, 204-210, DOI: 10.1039/C0SC00453G, Minireview 

Synthesis of boron doped polymeric carbon nitride solids and their use as metal-free catalysts for aliphatic C-H bond oxidation 
Yong Wang, Haoran Li, Jia Yao, Xinchen Wang and Markus Antonietti 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00475H, Edge Article 

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

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

In a typical chemical reaction, the goal is to find the best conditions to get the highest yield. Combinations of reagents, catalysts, temperatures and times are tested to find the optimal conditions. Finding the best combinations should require testing the majority of the possible combinations, but typically only 5–10 combinations are tested to avoid the ‘curse of dimensionality’ –  where the number of possible experiments grows exponentially with the number of variables. 

Now, US scientists reporting in Chemical Science say that, contrary to this reasoning, experience shows that synthesis and property optimisations are far easier to achieve than the curse of dimensionality suggests. They put forward the ‘OptiChem’ theory, concluding that the most efficient method is to change all important variables, performed with automated high-throughput synthesis.

Intrigued? Download the Edge article by Herschel Rabitz and colleagues to learn more.

Photocatalysis of organic molecules in fatty acid membranes offers a plausible method for energy transfer and storage in prebiotic systems. We don’t know how early cells were formed – one suggestion is that the initial cell like structures were made through the self-assembly of fatty acids to form vesicles. However, this hypothesis still leaves many questions, including how these vesicles could harness energy for chemical reactions – an essential step for creating more complex systems. 

In an Edge article published in Chemical Science, James Boncella and colleagues have reported that they developed a primitive energy transduction mechanism. Their research demonstrates that photocatalytic reactions involving polycyclic aromatic hydrocarbons (PAH) trapped in the vesicle membrane are capable of capturing and storing energy. 

The vesicles are made from a hydrophobic membrane of fatty acids and polycyclic aromatic hydrocarbons surrounding an interior void containing metal anions. This membrane acts as barrier that prevents charged molecules from entering and leaving the vesicle. In a series of chemical reactions electrons are transferred across the membrane and trapped in charged molecules contained in the interior void. The cycle uses the PAH in the membrane as a photocatalyst to reduce Fe(CN)₆^3- inside the vesicle. The PAH is then regenerated by oxidising EDTA molecules outside the cell which act as the electron source. Boncella explains that the cycle is a single electron process for harvesting energy. The next question is: “Can we use this energy to do useful chemistry?” 

Unlike conventional methods to create vesicles the team used a complex mixture of short chain fatty acids and polycyclic aromatic hydrocarbons based on the composition of carbonaceous meteorites. The team hopes that these conditions mimic the environment found on earth thousands of years ago.

James Boncella reveals more about his work in a Chemical Science audio file, which accompanies his Edge article. Download it for free and let us know what you think of his research.

A powerful strategy for selectively modifying the side-chains of proteins has been developed, which is hoped will enable the creation of new tools to investigate protein interactions involved in human diseases.

Modifying the side-chains of the amino acids that make up proteins is simple, but because a particular type of side-chain may appear many times in a given protein, modifying just one of them is a tough challenge. Brian Popp and Zachary Ball at Rice University, Houston, have been using chemical reactivity ideas and reaction design to try and solve this problem. 

In their solution, they decided to dispense with the standard approach of designing a highly selective reagent. Instead, they used a reagent that is hardly selective at all, but one that only works in the presence of a rhodium catalyst. The trick is to place the catalyst exactly where it’s needed by attaching it to a coiled peptide that binds to the right bit of the target protein. This brings the catalyst and the side-chain into close proximity, allowing them to react as soon as the reagent – a diazo derivative of styrene ­– is added.

Ball thinks that this approach is ‘a big step forward’. The main benefit is that the high reactivity of the diazo compound allows it to react with the side-chains of over half the naturally occurring amino acids, a broader range than any established method. The method is also highly specific, as any catalytic units that start to react where they are not wanted are quickly destroyed by reaction with water, which is the solvent for the reaction. 

 As well as looking to establish the robustness of their new method, future work may involve investigating how it could be used to tag, image, or modify the structure or function of natural proteins. “We believe this work will create powerful tools to investigate transient protein interactions, such as those along signalling pathways that lead to human disease,” says Ball.

Download the Edge article from Chemical Science for free to read more about this exciting work.

To encounter more exceptional research, sign up for the Chemical Science e-alert.

A greener, non-toxic method for brominating aromatic hydrocarbons has been developed by Japanese scientists. Using 9-mesityl-10-methylacridinium ion as the photocatalyst, Shunichi Fukuzumi‘s team at Osaka University selectively brominated a range of aromatic hydrocarbons and thiophenes under visible light irradiation, using aqueous hydrogen bromide as the Br source and oxygen as the oxidant.

 A number of bromination protocols use elemental bromine and N-bromosuccinimide as the Br sources, but these are toxic, hazardous and can over-brominate, producing mixtures. The photocatalytic reaction will enable scientists to synthesise brominated compounds on a large scale without the cost of isolation and purification.

Find out more by downloading Fukuzumi’s Chemical Science Edge article for free.

Do you know someone who has made a significant contribution to advancing the chemical sciences?

Our Prizes and Awards  recognise achievements by individuals, teams and organisations in advancing the chemical sciences. Winners receive up to £5000 and a medal or inscribed memento.

Showcase inspiring science and gain the recognition deserved – Nominate yourself or a colleague

Nomination categories include:

• Analytical Chemistry
• Biosciences
• Education 
• Environment, Sustainability & Energy 
• Industry & Technology 
• Inorganic Chemistry 
• Materials Chemistry 
• Organic Chemistry 
• Physical Chemistry 

Nominations close 31 January 2011

The latest issue (2) of Chemical Science is now online. Read it for free today!

The issue features a Mini review by Fraser Stoddart and colleagues on mechanised materials, which starts off with my favourite phrase from the whole issue:

‘…mankind has attempted to mimic the natural world—building wings to fly like the birds and fabricating systems to harness energy from the sun like our botanical brethren.’

Stoddart goes on to discuss several synthetic molecular machines that have been pinned down on surfaces to induce macroscale function and motion, then highlights some bioconjugated molecular devices which are capable of harnessing motion.

There is also a Perspective by Katsuhiko Ariga and colleagues, who illustrate how nanoscience and nanotechnology can be accessed physically from the macroscopic world according to three categories: physico-chemical properties,
chemical events and bio-related functions.

There’s plenty more, from nanolithography to lipid bilayer membranes to total synthesis.

Let us know what you think of the issue by leaving a comment below. Don’t forget you can sign up for the Chemical Science e-alerts and follow us on Twitter to stay abreast with the latest developments.

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

Ir-catalyzed highly selective addition of pyridyl C-H bonds to aldehydes promoted by triethylsilane 
Bi-Jie Li and Zhang-Jie Shi 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00419G, Edge Article 

Dialkylbiaryl phosphines in Pd-catalyzed amination: a user’s guide 
David S. Surry and Stephen L. Buchwald 
Chem. Sci., 2011, 2, 27-50, DOI: 10.1039/C0SC00331J, Perspective 

Diamine ligands in copper-catalyzed reactions 
David S. Surry and Stephen L. Buchwald 
Chem. Sci., 2010, 1, 13-31, DOI: 10.1039/C0SC00107D, Perspective 

Azomethine ylide annulations: facile access to polycyclic ring systems 
Chen Zhang, Deepankar Das and Daniel Seidel 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00432D, Edge Article 

Amine directed Pd(ii)-catalyzed C-H bond functionalization under ambient conditions 
Benjamin Haffemayer, Moises Gulias and Matthew J. Gaunt 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00367K, Edge Article 

Synthesis and carbene-transfer reactivity of dimeric nickel carbene cations supported by N-heterocyclic carbene ligands 
Carl A. Laskowski and Gregory L. Hillhouse 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00464B, Edge Article 

Metallacycle-mediated cross-coupling with substituted and electronically unactivated alkenes 
Holly A. Reichard and Glenn C. Micalizio 
Chem. Sci., 2011, Advance Article, DOI: 10.1039/C0SC00394H, Perspective 

Palladium-catalyzed coupling of functionalized primary and secondary amines with aryl and heteroaryl halides: two ligands suffice in most cases 
Debabrata Maiti, Brett P. Fors, Jaclyn L. Henderson, Yoshinori Nakamura and Stephen L. Buchwald 
Chem. Sci., 2011, 2, 57-68, DOI: 10.1039/C0SC00330A, Edge Article 

Total synthesis of all (-)-agelastatin alkaloids 
Mohammad Movassaghi, Dustin S. Siegel and Sunkyu Han 
Chem. Sci., 2010, 1, 561-566 DOI: 10.1039/C0SC00351D, Edge Article 

Continuous flow multi-step organic synthesis 
Damien Webb and Timothy F. Jamison 
Chem. Sci., 2010, 1, 675-680, DOI: 10.1039/C0SC00381F, Minireview 

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

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