Organocatalytic hydroboration of carbonyl compounds promoted by choline-based ionic liquids

The organocatalytic activity of choline-based ionic liquids in the hydroboration of ketones, aldehydes and carboxylic acids with pinacolborane was investigated. The method employed was based on a simple, inexpensive, biobased, reusable and environmentally friendly [Cho][OAc] catalyst. Detailed studies on catalyst screening, the optimization of reaction conditions, and substrate scope were carried out. [Cho][OAc] showed excellent tolerance to various functional groups and chemoselectivity towards C=O hydroboration, which occurred under mild conditions. Furthermore, it was shown that the reaction can be carried out under repetitive batch modes, allowing effective catalyst recycling and improving process productivity.