Laboratory Scale Continuous Flow Systems for the Enantioselective Phase Transfer Catalytic Synthesis of Quaternary Amino Acids
Articolo
Data di Pubblicazione:
2023
Citazione:
Laboratory Scale Continuous Flow Systems for the Enantioselective Phase Transfer Catalytic Synthesis of Quaternary Amino Acids / M. Krstic, S. Rossi, M. Sanz, A. Puglisi. - In: MOLECULES. - ISSN 1420-3049. - 28:(2023 Jan 19), pp. 1002.1-1002.12. [10.3390/molecules28031002]
Abstract:
The use of stereoselective phase-transfer catalysis as a reliable method for the enantioselec-
tive synthesis of optically active α-amino acid derivatives using achiral Schiff base esters has been
well-developed in batch in the last 40 years. Recently, continuous flow technology has become of great
interest in the academy and industry, since it offers safer process operating conditions and higher
efficiency compared to a traditional batch processing. Herein, we wish to report the first example
of enantioselective phase transfer benzylation of alanine Schiff base ester, under continuous flow
conditions. Two different methodologies were investigated: a liquid-solid phase transfer catalytic
benzylation using a packed-bed reactor and a liquid-liquid phase transfer catalytic benzylation in
continuous stirred-tank reactors. Liquid-liquid phase transfer process in flow showed slightly better
productivity than the batch process, while solid-liquid phase transfer benzylation proved much more
advantageous in terms of productivity and space-time yield. Furthermore, continuous flow system
allowed the isolation of benzylated product without any work up, with a significant simplification of
the process. In both cases, phase transfer asymmetric benzylation promoted by Maruoka catalyst
demonstrated high enantioselectivity of target quaternary amino ester in flow, up to 93% ee.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
continuous flow; quaternary stereocenter; phase transfer catalysis (PTC); enantioselective synthesis; packed-bed reactor; continuous stirred tank reactor; asymmetric catalysis
Elenco autori:
M. Krstic, S. Rossi, M. Sanz, A. Puglisi
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