title: A stereoselective switch: enantiodivergent approach to the synthesis of isoflavanones.
abstract: A modular six-step asymmetric synthesis of two naturally occurring and three non-natural isoflavanones containing tertiary α-aryl carbonyls is reported. This synthetic route, utilising a Pd-catalyzed decarboxylative asymmetric protonation, produces isoflavanones in excellent enantioselectivities from 76-97 %. A switch in the sense of stereoinduction was observed when different H(+) sources were employed, showing the first example of dual stereocontrol in an asymmetric protonation reaction. The first enantioselective synthesis of the naturally occurring isoflavanones sativanone and 3-o-methylviolanone has been accomplished.
authors.affiliation: Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4 (Ireland).
authors.forename: Robert
authors.initials: R
authors.lastname: Doran
authors.forename: Michael P
authors.initials: MP
authors.lastname: Carroll
authors.forename: Ramulu
authors.initials: R
authors.lastname: Akula
authors.forename: Bryan F
authors.initials: BF
authors.lastname: Hogan
authors.forename: Marta
authors.initials: M
authors.lastname: Martins
authors.forename: Séamus
authors.initials: S
authors.lastname: Fanning
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Guiry
keywords: asymmetric catalysis; dual stereocontrol; isoflavanones; natural products; palladium