Exploring the scope of tandem palladium and isothiourea relay catalysis for the synthesis of α-amino acid derivatives
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The scope and limitations of a tandem N-allylation/[2,3]-rearrangementprotocol are investigated through the incorporation of a variety of functionalgroups within an allylic phosphate precursor. This method uses readilyaccessible N,N-dimethylglycine aryl esters and functionalizedallylic phosphates, forming quaternary ammonium salts in situ in the presence of a palladium catalyst. Subsequentenantioselective [2,3]-sigmatropic rearrangement, promoted by the chiralisothiourea tetramisole, generates α-amino acid derivatives with two contiguousstereocenters. The incorporation of electron withdrawing ester and amide groupsgave the best results, furnishing the desired products in moderate to goodyields (29-70%), with low diastereocontrol (typically 60:40 dr) but highenantioselectivity (up to 90:10 er). These results indicate that substrate-catalystinteractions in the proposed transition state are sensitive to the substitutionpattern of the substrates.
Bitai , J , Slawin , A M Z , Cordes , D B & Smith , A D 2020 , ' Exploring the scope of tandem palladium and isothiourea relay catalysis for the synthesis of α-amino acid derivatives ' , Molecules , vol. 25 , no. 10 , 2463 . https://doi.org/10.3390/molecules25102463
Copyright © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
DescriptionFunding: This research was funded by the School of Chemistry, University of St Andrews. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award.
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