title: Enantioselective Synthesis of 3,5,6-Substituted Dihydropyranones and Dihydropyridinones using Isothiourea-Mediated Catalysis.
abstract: The scope of dihydropyranone and dihydropyridinone products accessible by isothiourea-catalyzed processes has been expanded and explored through the use of 2-N-tosyliminoacrylates and 2-aroylacrylates in a Michael addition-lactonization/lactamization cascade reaction. Notably, to ensure reproducibility it is essential to use homoanhydrides as ammonium enolate precursors with 2-aroyl acrylates, while carboxylic acids can be used with 2-N-tosyliminoacrylates, delivering a range of 3,5,6-substituted dihydropyranones and dihydropyridinones with high enantioselectivity (typically >90 % ee). The derivatization of the heterocyclic core of a 3,5,6-substituted dihydropyranone through hydrogenation is also reported.
authors.affiliation: School of Chemistry, University of St Andrews, North Haugh, St Andrews Fife, KY16 9ST, UK.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Stark
authors.affiliation: School of Chemistry, University of St Andrews, North Haugh, St Andrews Fife, KY16 9ST, UK.
authors.forename: Louis C
authors.initials: LC
authors.lastname: Morrill
authors.affiliation: School of Chemistry, University of St Andrews, North Haugh, St Andrews Fife, KY16 9ST, UK.
authors.forename: David B
authors.initials: DB
authors.lastname: Cordes
authors.affiliation: School of Chemistry, University of St Andrews, North Haugh, St Andrews Fife, KY16 9ST, UK.
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.affiliation: Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK.
authors.forename: Timothy J C
authors.initials: TJ
authors.lastname: O'Riordan
authors.affiliation: School of Chemistry, University of St Andrews, North Haugh, St Andrews Fife, KY16 9ST, UK. ads10@st-andrews.ac.uk.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Smith
keywords: Michael addition; dihydropyranones; dihydropyridinones; enantioselective catalysis; isothioureas