Bifunctional Behavior of Unsaturated Intramolecular Phosphane–Borane Frustrated Lewis Pairs Derived from Uncatalyzed 1, 4‐Hydrophosphination of a Dienylborane. Issue 35 (14th July 2015) - Chen, Guo‐Qiang
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(C6 F5 )2 to yield B/B/P systems. The 1, 4‐P/B system (C6 F5 )2 BCH2 CHCMeCH2 PMes2 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 (C6 F5 )2 BCH2 CHCMeCH2 P t Bu2 stops at the allylborane/benzaldehyde addition product. The related system (C6 F5 )2 BCH2 CHCMeCH2 PPh2 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. Abstract : P/B and yea : Three unsaturated C4 ‐bridged phospane/borane frustrated Lewis pair systems (P/B FLPs) were prepared by uncatalyzed hydrophosphination of a dienylborane. The systems are shown to be bifunctional and, in reactions with benzaldehyde, undergo both allyl borane addition and 1, 2‐borane/phosphane Lewis pair addition to the internal CC bond.