Alkylating Agents and Limit Test by Colour

Written by Dr John Knight on Thursday, 20 November 2014. Posted in Process Chemistry News

Alkylating agents

During the Scientific Update conference 'Organic Process Research and Development' in Cologne in September, amongst the many great talks was a tip I had not previously come across. Thomas Allmendinger (Novartis) was describing efforts to scale-up the hydrogenolysis of the benzylic hydroxyl by first forming the carbonate with methyl chloroformate. A really interesting talk within which was a single slide describing how they used a simple colour test to monitor for residual methyl chloroformate. The reaction is shown below. They could calibrate the colour of test solutions with the residual chloroformate and although on this occasion they had to use visual comparison, in principle at least a photometric method of analysis is feasible.

Bookmark and Share

Catalytic C-H Functionalisation; Enantioselective Formation of Beta-Lactams

Written by Dr Trevor Laird on Thursday, 20 November 2014. Posted in Latest News, Process Chemistry News

Catalytic C-H Functionalisation; Enantioselective Formation of Beta-Lactams

An interesting article from the group of Nicolai Cramer at Lausanne (Angew Chem Int Ed, 2014, 53, 9064) describes the conversion of alpha-chloro amides, which have an additional feature of a benzylic or similar active methylene group on the nitrogen, into beta-lactams by carbon-carbon bond formation and loss of HCl. The reaction takes place under palladium catalysis in toluene at reflux with base present, the enantioselectivity being induced when a chiral phosphoramidite ligand is present. Yields of beta-lactams are generally in the 90-95% range with high enantiomeric ratios. Occasionally, when a heterocylic group is present instead of the phenyl of the benzyl, 6-membered rings can be formed. As yet the reaction is somewhat limited to amides with two alkyl groups attached to the nitrogen but further research may allow expansion of the scope.

Bookmark and Share

Catalytic C-H Functionalisation

Written by Dr Trevor Laird on Thursday, 20 November 2014. Posted in Process Chemistry News

Catalytic C-H Functionalisation

This is a really hot area of organic chemistry and promises to be of use to process chemists in providing new routes to molecules. In 2009, a collaboration known as the Center for Selective C-H Functionalisation was set up with funding from the National Science Foundation in USA. 6 chemists (5 synthetic and 1 computational) were involved at that time. Phase II which began in 2012/3 comprises 23 research groups in 15 universities (for a full list see Angew Chem Int Ed, 2014, 53, 10256 which gives more details of the collaborations which are all in USA). Europe has much experience of these joint programmes and Scientific Update coordinated some of the UK's LINK schemes in Asymmetric Synthesis in the 1990s. It will be interesting to see how well the groups work together. Since its inception the Center has published 70 papers, over half of which have multiple faculty members so this a good sign. The Center is hoping to expand into Europe and Asia shortly. This must be good news for organic chemistry and for the process chemistry community.

Bookmark and Share

New Journal: Organic Chemistry Frontiers

Written by Dr Trevor Laird on Thursday, 20 November 2014. Posted in Process Chemistry News

New Journal: Organic Chemistry Frontiers

This journal, which started in January 2014 is a joint publication between the RSC and the Chinese Chemical Society. As the RSC website says " The journal welcomes articles which make a significant contribution to the field of organic chemistry by reporting either new or significantly improved protocols or methodologies". The journal; will have review articles as well as full papers. The journal is free to access for the first 2 years see http://www.rsc.org/publishing/journals for more info.

 

Bookmark and Share

Metathesis

Written by Dr Will Watson on Wednesday, 06 August 2014. Posted in Process Chemistry News

Specialised Session at Modern Synthetic Methods & Chiral USA, Orlando May 2014.

The session consisted of 5 presentations which are summarised below with the summaries concentrating specifically on the metathesis reactions presented, although several speakers also described some very interesting chemistry used to make the metathesis substrates.

Bookmark and Share

Hydrogen Atom Transfer to Deliver Thermodynamically Preferred Product

Written by Dr John Knight on Monday, 19 May 2014. Posted in Process Chemistry News

Heterogeneous catalytic hydrogenation is of course a much-used chemical reaction and very efficiently delivers product with high atom economy.  The chemo- and stereoselectivity has been studied many times over the years and is in general fairly predictable based on steric impediment and the ability of the substrate to approach the catalyst surface for hydrogen transfer.

Bookmark and Share

Follow Us