title: Contrasting Frustrated Lewis Pair Reactivity with Selenium- and Boron-Based Lewis Acids.
abstract: The activation of π-bonds in diynyl esters has been investigated by using soft and hard Lewis acids. In the case of the soft selenium Lewis acid PhSeCl, sequential activation of the alkyne bonds leads initially to an isocoumarin (1 equiv PhSeCl) and then to a tetracyclic conjugated structure with the isocoumarin subunit fused to a benzoselenopyran (3 equiv PhSeCl). Conversely, the reaction with the hard Lewis acidic borane B(C6 F5 )3 initiates a cascade reaction to yield a complex π-conjugated system containing phthalide and indene subunits.
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK.
authors.forename: Lewis C
authors.initials: LC
authors.lastname: Wilkins
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK.
authors.forename: Benjamin A R
authors.initials: BA
authors.lastname: Günther
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK.
authors.forename: Melanie
authors.initials: M
authors.lastname: Walther
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK.
authors.forename: James R
authors.initials: JR
authors.lastname: Lawson
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wirth
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Cymru/Wales, CF10 3AT, UK. MelenR@cardiff.ac.uk.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Melen
keywords: annulation; cyclization; domino reactions; frustrated Lewis pairs; main-group elements