Hydroboration generally requires the presence of a catalyst to lower the barrier for hydride transfer. This work reports on the first catalyst-free CO hydroboration with a neutral boron compound, the nucleophilic diborane [HB(hpp)] , 1 (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate). Further hydroboration reactions to bis(boryl)acetals are possible. In acetonitrile, but not in dichloromethane solutions, hydroboration of a first CO is followed by hydroboration of a second CO molecule. Detailed kinetic measurements for both hydroboration steps were carried out and the influence of the solvent and the addition of a Lewis base on the rate constants analyzed. In contrast to catalyst-free hydroboration of CO , hydroboration of the less electrophilic acetone requires the presence of an activating Lewis acid.

Diboration of unsaturated organic compounds is an extremely useful reaction in synthetic chemistry. Herein, we report the first diboration of a nitrile by an electron-rich diborane, mediated by an electrophilic borane. The reaction is metal-free, and all of the reagents are readily available.

Diborierungen von ungesättigten organischen Molekülen sind äußerst nützliche Reaktionen in der Synthesechemie.H ier berichtenw ir über die erste Diborierung eines Nitrils durche in elektronenreiches Diboran, vermittelt durch ein elektrophiles Boran. Die Reaktion ist metallfrei und alle Reagenzien sind leichtverfügbar.