Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations
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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).
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
Organic & Biomolecular Chemistry
Copyright © 2019 The Author(s). This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1039/C9OB00703B
DescriptionWe 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-c877c993dc5d
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