Monday 27 May 2013

Friday 24 May 2013

A new method for producing clean hydrogen



TEM_image_Au-a-Fe2O3_catalyst






Duke University engineers have developed a novel method for producing clean hydrogen, which could prove essential to weaning society off of fossil fuels and their environmental implications. While hydrogen is ubiquitous in the environment, producing and collecting molecular hydrogen for transportation and industrial uses is expensive and complicated. Just as importantly, a byproduct of most … more…

Thursday 23 May 2013

World Drug Tracker: Scientists sequence genome of ‘sacred lotus,’ may ...

World Drug Tracker: Scientists sequence genome of ‘sacred lotus,’ may ...: Scientists sequence genome of ‘sacred lotus,’ may hold anti-aging secrets A team of 70 scientists from the U.S., China, Austral...

One-Pot Method for Regioselective Bromin­ation and Sequential Carbon–Carbon Bond-Forming Reactions of Allylic Alcohol Derivatives

One-Pot Method for Regioselective Bromin­ation and Sequential Carbon–Carbon Bond-Forming Reactions of Allylic Alcohol Derivatives
European Journal of Organic Chemistry Noriki Kutsumura, Yusuke Matsubara, Kentaro Niwa, Ai Ito and Takao Saito
DOI: 10.1002/ejoc.201300173

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Di- or trisubstituted olefins were synthesized in high yields with excellent regio- and cis–trans selectivities in one-pot reactions, including a regioselective DBU-promoted trans HBr elimination. This one-pot methodology could become a straightforward transformation of “straight” alkenes into “Y-shaped” alkenes.


An efficient one-pot method for the regioselective bromination of allylic alcohol derivatives (two-step reaction sequence) followed by Sonogashira, Negishi, or Suzuki–Miyaura coupling reactions in the same reaction vessel (three-step reaction sequence) has been developed. The key reaction in these one-pot systems is the regioselective DBU-promoted trans HBr elimination of vicinal dibromides bearing an adjacent O-functional group.

Synthetic Uses of Ammonia in Transition-Metal Catalysis

European Journal of Organic Chemistry


Jinho Kim, Hyun Jin Kim and Sukbok Chang
DOI: 10.1002/ejoc.201300164
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Although ammonia (NH3) is a cheap, abundant, and readily available nitrogen source, it has rarely been used in transition-metal catalysis, due to several obstacles. However, significant advances in the metal-mediated utilization of ammonia have been made recently. This review presents the most recent examples in metal-mediated amination and other relevant reactions with ammonia or ammonium salts.
http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201300164/abstract

Ammonia (NH3) is a cheap, abundant, and readily available nitrogen source, being one of the chemicals produced in the greatest quantities. Whereas ammonia is utilized mainly as a feedstock for the production of fertilizers, it is also employed in industry as a component of various nitrogen-containing compounds. In metal catalysis, in contrast, ammonia has been used only with limited success, due to several difficulties such as generation of stable Lewis acid-base adducts, facile ligand exchange for ammonia in active metal complexes, a propensity towards undesired second transformations of initially formed species, and the requirement for special equipment to run the reactions. Despite these obstacles, the direct use of ammonia in catalysis has continuously attracted great interest, leading recently to significant progress. Whereas liquid or gaseous ammonia were most commonly employed in the past, under harsh conditions, notable catalytic reactions using easy-to-handle ammonium salts under milder and more convenient conditions have now been developed. In this review we briefly describe the most recent examples of transition-metal-catalyzed reactions using ammonia or ammonium salts.