Carbonyl imidazolide activation

Written by Dr John Knight on Thursday, 19 July 2012. Posted in Process Chemistry News

I noted with interest the article by Sarpong et al about activation of carbonyl imidazolides (Org Lett, 2012, 14 (8), 1970) and was reminded of a couple of earlier reports that I’d read.  Sarpong et al report that pyridinium hydrochloride can promote the formation of oxazolidinones, as shown below, as well as accelerating the esterification carboxylic acids with imidazole carbamates.

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Previous reports to which I refer are from Gilday et al (OPRD, 2009, 13 (1), 106) where they reported the accelerating effect of imidazole hydrochloride when coupling anilines with carbonyl imidazolides and work reported in the text ‘Process Chemistry in the Pharmaceutical Industry’, ed T Braish and K Gadamasetti.  This later example is again of interest to me as it brings further intriguing details to light in CDI-mediated coupling reactions and the excellent work and enhanced understanding that development chemists bring to the fore.  In this case, it was the carbon dioxide was important and actually helped to promote the desired chemistry, with the intermediacy of the ‘anhydride’ species.  The coupling was inferior when carbon dioxide was purged from the system and could be ‘kick-started’ by bubbling carbon dioxide through the mixture.

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About the Author

Dr John Knight

Dr John Knight

John Knight gained a first class honours degree in chemistry at theUniversity of Southampton, UK. John remained at Southampton to study for his PhD in synthetic methodology utilizing radical cyclisation anddipolar cyloaddition chemistry. After gaining his PhD, John moved to Columbia University, New York, USA where he worked as a NATOPostdoctoral Fellow with Professor Gilbert Stork. John returned to theUK in 1987 joining Glaxo Group Research (now GSK) as a medicinalchemist, where he remained for 4 years before moving to the processresearch and development department at Glaxo, where he remained for afurther 3½ years. During his time at Glaxo, John worked on a number ofprojects and gained considerable plant experience (pilot andmanufacturing). In 1994 John moved to Oxford Asymmetry (later changingits name to Evotec and most recently to Aptuit) when it had just 25staff. John’s major role when first at Oxford Asymmetry was to workwith a consultant project manager to design, build and commission asmall pilot plant, whilst in parallel developing the chemistry PRDeffort at Oxford Asymmetry. The plant was fully operational within 18months, operating to a 24h/7d shift pattern. John continued to run thepilot plant for a further 3 years, during which time he hadconsiderable input to the design of a second plant, which was completedand commissioned in 2000. After an 18-month period at a smallpharmaceutical company, John returned to Oxford in 2000 (by now calledEvotec) to head the PRD department. John remained in this position for6.5 years, during which time he assisted in its expansion, establisheda team to perform polymorph and salt screening studies and establishedand maintained high standards of development expertise across thedepartment. John has managed the chemical development and transfer ofnumerous NCE’s into the plant for clients and been involved in processvalidations. He joined Scientific Update in January 2008 as Scientific Director.

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