Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations
Abstract
An evaluation of a range of aryl, alkyl and vinyl esters as prospective C(1)-ammonium enolate precursors in enantioselective Michael addition-lactonisation processes with (E)-trifluoromethylenones using isothiourea catalysis is reported. Electron deficient aryl esters are required for reactivity, with 2,4,6-trichlorophenyl esters providing optimal product yields. Catalyst screening showed that tetramisole was the most effective isothiourea catalyst, giving the desired dihydropyranone product in excellent yield and stereoselectivity (up to 90:10 dr and 98:2 er). The scope and limitations of this process have been evaluated, with a range of diester products being generated after ring-opening with MeOH to give stereodefined dihydropyranones with excellent stereocontrol (10 examples, typically ~90:10 dr and >95:5 er).
Citation
Young , C M , Taylor , J E & Smith , A D 2019 , ' Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations ' , Organic & Biomolecular Chemistry , vol. 17 , no. 19 , pp. 4747-4752 . https://doi.org/10.1039/C9OB00703B
Publication
Organic & Biomolecular Chemistry
Status
Peer reviewed
ISSN
1477-0520Type
Journal article
Description
We thank the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement no. 279850 (CMY, JET). ADS thanks the Royal Society for a Wolfson Merit Award. We also thank the EPSRC UK National Mass Spectrometry Facility at Swansea University. The data underpinning this research can be found at DOI: https://doi.org/10.17630/cb133261-b58e-4d72-b380-c877c993dc5dCollections
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