Tharwat Mohy El Dine
University of British Columbia
Currently, a post-doctorate at the PERRIN LAB (since October 2016), University of British Columbia, Vancouver campus. The research project is multidisciplinary combining both organic chemistry and biology.My PhD thesis titled ''New Insights in Amide Bond Formation Mediated by Boron-Based Catalysts’’ was done at the LCMT laboratory, University of Caen Normandie (Jan 2013-Apr 2016) and supervised by Dr. Jerome Blanchet and Prof. Jacques Rouden. I did my M2 in ''Synthesis, Catalysis and Sustainable Chemistry'' for the year 2011/2012 at the University of Claude Bernard Lyon 1, France and my Bachelor studies in ''General Chemistry'' at the Lebanese University, Lebanon.
The prominence of fluorinated aromatic compounds[1] in pharmaceuticals, agrochemicals, material sciences and 18F radiotracers for positron emission tomography (PET) have urged significant advances in the methods for aryl C-F bond formation.[2] Nevertheless, interest in Balz-Schiemann reaction[3] and variants thereof persists as fluorination on aryls continues to be a challenge, even if the Balz-Schiemann reaction suffers from several drawbacks such as harsh conditions, variable yields and safety concerns related to the stability of some aryl diazonium intermediates.[4] Thus, there is an urgent need to develop an improved environmentally friendly fluorination protocol that would provide a rapid and safe access to aryl fluorides.
A single report demonstrated the efficiency of potassium perfluoroorganyltrifluoroborates as fluoride sources in Balz-Schiemann transformation.[5] To the best of our knowledge, this is the only protocol that makes use of organotrifluoroborates, however with several limitations as the narrow scope (one diazonium substrate tested), high temperatures (>138 °C) and the necessity of isolating and drying the aryldiazonium organylfluoroborates.
In this context, we developed an efficient protocol promoting mild and practical one-pot synthesis of aryl fluorides from aryl amines using cheap and easy accessible organotrifluoroborates (Scheme 1).[6]
A range of substrates was synthesized in a similar fashion to the classical Blaz-Schiemann, but without the need of any intermediate or salt isolation.
Further optimization allowed the extension of this method to solid-supported fluorination using recyclable solid-supported RBF3-. This procedure will be applied to flow reactors where continuous in situ diazotization/fluorodediazoniation would enable the elution of the desired fluoroarenes while retaining the boronic acid that can be regenerated as the organotrifluoroborate.
[1] T. Okazoe, Proc. Jpn. Acad., Ser. B, 2009, 85, 276 – 289.
[2] M. G. Campbell, T. Ritter, Chem. Rev. 2015, 115, 612 – 633.
[3] G. Balz, G. Schiemann, Ber. Dtsch. Chem. Ges. 1927, 60, 1186 – 1190.
[4] A. J. Cresswell, S. G. Davies, P. M. Roberts, J. E. Thomson, Chem. Rev. 2015, 115, 566 – 611.
[5] O. Sadek, T. Mohy El Dine, E. Gras, D. Perrin, manuscript under preparation.
[6] V. V. Bardin, H.-J. Frohn, J. Fluor. Chem. 2013, 156, 333 – 338.
B - Recycling, green chemistry, environment impact & sustainability , B - Bioinorganic chemistry and application in medicine
