title: Bifunctional Behavior of Unsaturated Intramolecular Phosphane-Borane Frustrated Lewis Pairs Derived from Uncatalyzed 1,4-Hydrophosphination of a Dienylborane.
abstract: Three unsaturated C4 -bridged phospane/borane frustrated Lewis pairs (P/B FLPs) are prepared by uncatalyzed hydrophosphination of a dienylborane. The systems are bifunctional. Consequently, two examples undergo clean hydroboration reactions with HB(C6F5)2 to yield B/B/P systems. The 1,4-P/B system (C6F5)2B-CH2CH=CMeCH2PMes2 reacts with benzaldehyde initially by allylborane addition, followed by internal P/B FLP addition to the pendant C=C double bond, to yield a bicyclic product. The corresponding reaction of (C6F5)2B-CH2CH=CMeCH2PtBu2 stops at the allylborane/benzaldehyde addition product. The related system (C6F5)2B-CH2CH=CMeCH2PPh2 shows a similar bifunctional reaction pattern, whereby allylborane addition to benzaldehyde is combined with P/B addition to a second aldehyde equivalent to form the eight-membered heterocyclic 1:2 addition product.
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Gerald
authors.initials: G
authors.lastname: Kehr
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Birgit
authors.initials: B
authors.lastname: Wibbeling
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).. erker@uni-muenster.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Erker
keywords: FLP addition; allylborane; boron; phosphorus; rearrangement