Dynamic Kinetic Resolution of primary benzylamines by using recyclable palladium supported on dolomite

Title : Dynamic Kinetic Resolution of primary benzylamines by using recyclable palladium supported on dolomite

Abstract:

Enantiomerically pure amines are important building blocks for the synthesis of molecules with potential biological activity and are employed as essential intermediary to chemistry, pharmaceuticals and agrochemistry industries. Dynamic Kinetic Resolution (DKR) has been a method largely employed to synthesize optically pure compounds, in which both Kinect enzymatic resolution and racemization steps should demonstrate great compatibility. In this work, palladium catalyst supported on dolomite (2.5% PdDOL) had both activity and selectivity studied in DKR reactions of different benzylamines, which are substituted at the aromatic ring with methyl and fluorine groups. Several reaction conditions were used in the catalytic activity studies of the 2.5% PdDOL, including the use of different temperatures (80 ºC and 95ºC), reaction times (6 to 24h) and acylating agents (ethyl acetate, isopropyl acetate and isoamyl acetate). Furthermore, the effects of four different ionic liquids, two ammonium salts and two phosphonium salts, as additives was also investigated.

For the first time in literature a palladium catalyst supported on dolomite was used for Dynamic Kinetic Resolution reactions of primary amines. The results obtained demonstrated good activity and selectivity, since the starting material was converted to the desired product by up to 100%. The temperature of 95 ºC provided excellent conversion values for (R,S)-1-phenylethylamine, that was used as a model compound. Ethyl acetate as acyl donor proved to be the most efficient acylating agent, as it presents a smaller and less hindered chain, facilitating the enzymatic acetylation step. Reaction times were optimized using ionic liquids, especially for (R,S)-1-phenylethylamine and (R,S)-1-(4-fluoro)phenylethylamine.

Audience take-away:

• The audience will be able to show the perspectives about the use of catalysis in amines synthesis;
• The audience will help to improve the disclosure of results and international network

Biography:

Dr. Fernanda A. de Siqueira is a Professor of Chemistry at Federal University of São Paulo, Brazil. She obtained her undergraduate degree in Chemistry (2001) from Federal University of Juiz de Fora, Minas Gerais, Brazil. Siqueira received her Ph.D. in Chemistry from the University of São Paulo in 2008. After 2 years as a postdoctoral fellow at University of Campinas, she was appointed to the Department of Chemistry at Federal University of São Paulo as a Lecturer. She was promoted to Associate Professor in 2018. Current research in the Siqueira’s Lab emphasize the metal heterogeneous catalysis and dynamic kinetic resolution.