Comparison of decamethyldizincocene [(η ~5-Cp*) _2Zn _2] versus decamethylzincocene [Cp* _2Zn] and diethylzinc Et _2Zn as precatalysts for the intermolecular hydroamination reaction

摘要

A comparison of the Zn-Zn bonded species [(η ~5-Cp*) _2Zn _2] versus the related organometallic zinc compound [Cp* _2Zn] and ZnEt _2 for the intermolecular hydroamination reaction in the presence of equimolar amounts of [PhNMe _2H][B(C 6F 5) 4] is reported. All compounds show high reaction rates under mild conditions and a good functional group tolerance for the addition of aniline derivatives to primary alkynes. Within this series the metallocene [Cp* _2Zn] is the most active one, whereas the zinc-zinc bonded species [(η ~5-Cp*) _2Zn _2] shows the best selectivity. Most remarkable is the unexpected excellent catalytic performance of the zinc-zinc bonded species [(η ~5-Cp*) _2Zn _2].