Abstract :
[en] Herein is described the development of an intensified continuous flow process for the preparation of a library of alkyl phosphonates through a Michaelis-Arbuzov rearrangement. A careful process optimization and thorough analysis of the competitive reactions led to a very attractive protocol with unprecedented productivities (up to 4.97 kg of material per day) and a low environmental footprint with the absence of solvent, additives, catalysts, and waste. In-line low-field 31P NMR monitoring was conveniently implemented for rapid optimization and process monitoring. Two key alkyl phosphonate intermediates were also assessed for the unprecedented diazene dicarboxylate-mediated electrophilic amination under continuous flow conditions toward the α-aminophosphonic acid derivatives of Pphenylalanine and Palanine, bioisosters of the natural amino acids phenylalanine and alanine, respectively.
Funding text :
This work was supported by the F.R.I.A.-FNRS (Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture, Belgium) and the University of Liège (Welcome Grant WG-13/03, JCMM). T.T. is a F.R.I.A.-FNRS PhD student fellow.
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