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Showing posts with label ORGANIC CHEMISTRY. Show all posts
Showing posts with label ORGANIC CHEMISTRY. Show all posts

Tuesday 6 August 2013

How to draft a patent

Wednesday 31 July 2013

The Sulfonamide Motif as a Synthetic Tool




Sulfonamides are well known motifs in medicinal chemistry, forming a large family of antibacterial agents as well as being found in numerous other drugs.  The chemistry of this functional group, however, is less well documented.  This review seeks to bring together the various applications and advantages of this motif in organic synthesis, which includes the sulfonamide as an activating group, protecting group, leaving group and as a molecular scaffold.
http://www.ingentaconnect.com/content/stl/jcr/2010/00000034/00000010/art00001


 The Sulfonamide Motif as a Synthetic Tool
Jonathan Wilden obtained his PhD from the University of Southampton in 2001 having worked on the total synthesis of the marine natural product pseudopterosin with Professor David Harrowven.  He then moved to the University of Sussex, Brighton, UK where his interest in sulfonamide chemistry began, working with Professor Steve Caddick.  In 2004 he was appointed lecturer at University College London where his research interests include the synthesis of medicinally important compounds and exploitation of the sulfonamide group in organic synthesis.

Tuesday 30 July 2013

Boron vapour trail leads to heterofullerenes

borafullerene
The simple route to borafullerenes could open up an interesting new avenue of heterofullerene research © Wiley-VCH
A team of scientists has developed a simple way to synthesise heterofullerenes – fullerenes with atoms other than carbon in their structure – by exposing fullerenes to boron vapour during their growth. They found that atom exchange with a carbon takes place to form a derivative known as borafullerene. The team believes the process can be easily scaled up and applied to other all-carbon analogues including nanotubes or graphene.
read all at

Friday 26 July 2013

One-Pot Approach to α,β-Unsaturated Carboxylic Acids

thumbnail image: One-Pot Approach to α,β-Unsaturated Carboxylic Acids

 

One-Pot Approach to α,β-Unsaturated Carboxylic Acids

Carboxylation of alkynes with carbon dioxide in a one-pot approach could become a practical route to unsaturated carboxylic acids
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Concise Total Synthesis of a Newly Discovered Alkaloid

 








A concise synthesis of a novel alkaloid natural product with the pyrroloindoloquinazoline skeleton has been devised
Read more

Tuesday 23 July 2013

Nano-Technoloogy Makes Medicine Greener


The ultra small nanoreactors have walls made of lipids. During their fusion events volumes of one billionth of a billionth of a liter were transferred between nanoreactors allowing their cargos to mix and react chemically. We typically carried out a million of individual chemical reactions per cm2 in not more than a few minutes. (Credit: Image courtesy of University of Copenhagen)http://www.sciencedaily.com/releases/2011/11/111103132357.htm
 Researchers at the University of Copenhagen are behind the development of a new method that will make it possible to develop drugs faster and greener. Their work promises cheaper medicine for consumers.
Over the last 5 years the Bionano Group at the Nano-Science Center and the Department of Neuroscience and Pharmacology at the University of Copenhagen has been working hard to characterise and test how molecules react, combine together and form larger molecules, which can be used in the development of new medicine.http://www.sciencedaily.com/releases/2011/11/111103132357.htm



Sunday 21 July 2013

The first total synthesis of fuscain

First total synthesis of fuscain

First total synthesis of fuscain


Fuscain is a new furanolactam isolated from the sponge Phacellis fusca from the South China Sea. Furan analogues isolated from marine organisms have valuable medicinal properties. The first total synthesis of fuscain is reported in Journal of Chemical Research December issue. The key step in the synthesis is the formation of seven-membered lactam by acylation of a furan ring using the mild Lewis acid CuSO4•5H2O.
Fuscain, a new furanolactam which was originally isolated from the sponge Phacellis fusca collected in South China Sea, showed a moderate cytotoxicity toward P388 and L1210 cell lines. The same sponge yielded three pyrrololactam alkaloids: saldisin, 2-bromoaldisin and debromohymenialdisin.2 Recently, furan analogues isolated from marine organisms have shown anticancer,3–5 antibacterial,6 anticoagulant, antifungal, antimalarial,  antiplatelet, antituberculosis and antiviral activities11. Aldisin-based derivatives can be easily synthesised. However, it is still a challenge to synthesise fuscain. Hence the biological effects of fuscain and its derivatives on cell cycle progression and antitumour activities have rarely been reported. The synthetic route to fuscain is shown below.
The key step is an intramolecular Friedel–Crafts cyclisation to form the seven-membered ring. Various Lewis acids (polyphosphoric acid, POCl3, polyphosphoric acid–acetic acid, POCl3–P2O5, TFA or MSA) have been reported for Friedel– Crafts cyclisation.13,14. Initially, we selected PPA and P2O5 as catalysts but no product was obtained. Because of the structural difference between Alidisin and fuscain, the aromaticity of furan ring is less than a pyrrole ring, and a furan ring usually polymerised under acidic conditions, we selected a relatively mild Lewis acid CuSO4•5H2O to complete the intramolecular cyclisation to form fuscain.


Source: Journal of Chemical Research, Volume 36, Number 12, December 2012 , pp. 736-737(2)
doi: 10.3184/174751912X13528167435099
Yuan-wei Liang, Xiao-jian Liao, Chang-jun Wang, Jin-zhi Guo, Shuo Li and Shi-hai Xu*
Department of Chemistry, Jinan University, Guangzhou 510632, P. R. China



 


Wednesday 17 July 2013

Building nanographene by organic synthesis



Direct C-H coupling of pyrene makes nanographenes with defined shape and edge structures

Direct C-H coupling of pyrene makes nanographenes with defined shape and edge structures

Japanese scientists are making tiny fragments of graphene using direct
cross-coupling of C-H bonds to determine what effect size and edge geometry
have on the properties of carbon materials. By bolting together aromatic hydrocarbons, they can
build nanographene fragments with defined shapes in an attempt to relate geometry to performance.
Speaking at the RSC’s seventh International Symposium on Advancing the Chemical Sciences in Edinburgh, UK, Kenichiro Itami from Nagoya University explained .............read all at

Tuesday 16 July 2013

A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)

A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)
A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)

Rauvolfia tetraphylla Linn. (syn. R. canescens L., family: Apocynaceae) holds an important position in the Indian traditional system of medicine, and has other immense applications. This particular plant is regarded as a rich source of a wide variety of important alkaloid constituents such as reserpine, reserpiline, raujemidine, isoreserpiline, deserpidine, aricine, ajmaline, ajmalicine, yohimbines, serpentine, sarpagine, vellosimine and tetrphylline. However, there is no report on the terpenoid constituent from this plant, and we report the isolation from the air-dried stems and branches of R. tetraphylla and structural elucidation of a new labdane diterpene, 3-hydroxy-labda-8(17),13(14)-dien-12(15)-olide (1; Fig. 1) bearing  an unusual -lactone moiety.
Structure of labdane diterpene
Fig. 1 Structure of labdane diterpene
Goutam Brahmachari*, Lalan Ch. Mandal, Dilip Gorai, Avijit Mondal, Sajal Sarkar and Sasadhar Majhi
Doi: 10.3184/174751911X13220462651507

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Novel uses of nanoparticle catalytic systems

Novel uses of nanoparticle catalytic systems
Novel uses of nanoparticle catalytic systems

Easily prepared and recoverable nanoparticles with a diameter of 10–40 nm, with a high surface area and stability may provide a catalytic system or the support for a catalyst.

Friday 12 July 2013

Turning carbon dioxide into something useful -Carbon dioxide reduced to formate by iridium pincer catalyst







http://www.rsc.org/chemistryworld/2013/07/iridium-catalyst-carbon-dioxide-reduction-formate

New research shows that a water-soluble catalyst developed by scientists in the US can electrocatalytically transform carbon dioxide into a useful chemical feedstock.
The global demand for fuel is rising, as are carbon dioxide levels in the atmosphere. Recent studies have attempted to address the global carbon imbalance by exploring ways to recycle carbon dioxide into liquid fuels. Formate, the anion of formic acid, is an intermediate of carbon dioxide reduction and can be used as a fuel in formic acid fuel cells. However, the selective production of formate, without using organic solvents, is challenging. Water, being inexpensive and environmentally-friendly, is obviously preferred over organic solvents as a reaction medium. On the other hand, the reduction of carbon dioxide in water is complicated by the reduction of water to hydrogen being a more kinetically favourable process.
 http://www.rsc.org/chemistryworld/2013/07/iridium-catalyst-carbon-dioxide-reduction-formate


Thursday 4 July 2013

Catalyst duo exerts powerful stereocontrol

diastereomer
The dual catalyst enables selective access to the required stereoisomer © Science/AAAS

Chemists from the Swiss Federal Institute of Technology, ETH Zurich, have teamed chiral catalysts in pairs to selectively drive a reaction towards desired stereoisomeric products with high selectivity. Each catalyst activates one reagent and controls its substituent arrangement as it bonds to the other to form two neighbouring chiral centres. ‘We have shown that it is possible to develop fully stereodivergent reaction processes,’ says Erick Carreira, who led the work. ‘We expect that additional reactions displaying full stereodivergency will be identified.’

read all at
http://www.rsc.org/chemistryworld/2013/05/catalyst-duo-powerful-stereocontrol-diastereomer

References

S Krautwald et alScience, 2013, DOI: 10.1126/science.1237068