Monomeric Magnesium Catalyzed Alkene and Alkyne Hydroboration

In this work, two monomeric magnesium alkyl complexes (1 and 2) were prepared using bis(phosphino)carbazole framework and among them 1 has been used as a catalyst for hydroboration of alkenes and alkynes with pinacolborane (HBpin). A broad variety of aromatic and aliphatic alkenes and alkynes were efficiently reduced. Anti-Markovnikov regioselective hydroboration of alkenes and alkynes was achieved, which was confirmed by deuterium-labelling experiments. The work represents the first example of the use of magnesium in homogeneous catalytic hydroboration of alkene with broad substrate scope. Experimental mechanistic investigations and DFT calculations provided insights into the reaction mechanism. Finally, the hydroboration protocol was extended to terpenes.

Automated summary

In this study, two monomeric magnesium alkyl complexes were prepared using bis(phosphino)carbazole framework, and one of them (1) was utilized as a catalyst for the hydroboration of alkenes and alkynes with pinacolborane (HBpin). Various aromatic and aliphatic alkenes and alkynes were efficiently reduced. The study achieved anti-Markovnikov regioselective hydroboration and provided mechanistic insights through experimental investigations and DFT calculations. Additionally, the hydroboration protocol was successfully extended to terpenes.