title: Observation of a thermally induced Bora-Nazarov cyclization at a phosphole framework.
abstract: The reaction of the bis(enynyl)phosphanes 6 a,b with the electrophilic borane reagents RB(C6 F5 )2 (R=C6 F5 , CH2 CH2 Ph, CH3 ) gave phospholes cleanly in a 1,1-carboboration reaction sequence. Depending on the steric bulk, the resulting 2,5-alkenylphospholes underwent a thermally induced bora-Nazarov type cyclization. The equilibrium situation of these examples of a bora-Nazarov type cyclization was investigated in detail by NMR spectroscopy, X-ray crystal structure analysis, and DFT calculations.
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).|Present address: Department of Chemistry, University of Toronto, 80 St. George Street, M5S 3H6, Toronto, Ontario (Canada).
authors.forename: Juri
authors.initials: J
authors.lastname: Möbus
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Gerald
authors.initials: G
authors.lastname: Kehr
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Christian
authors.initials: C
authors.lastname: Mück-Lichtenfeld
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany). erker@uni-muenster.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Erker
keywords: 1,1-carboboration reactions; bora-Nazarov reaction; conjugated π-systems; cyclization; phospholes