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Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition–lactonisations

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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).

Graphical abstract: Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition–lactonisations

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Publication details

The article was received on 26 Mar 2019, accepted on 08 Apr 2019 and first published on 11 Apr 2019


Article type: Paper
DOI: 10.1039/C9OB00703B
Citation: Org. Biomol. Chem., 2019, Advance Article

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    Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition–lactonisations

    C. M. Young, J. E. Taylor and A. D. Smith, Org. Biomol. Chem., 2019, Advance Article , DOI: 10.1039/C9OB00703B

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