Investigation Towards the Asymmetric CBS-Catalysed Reduction of Aryl Methyl Ketones with Electrochemically in Situ Generated BH3

The aim of this investigation was to explore the possibility to perform an asymmetric reduction, utilising a CBS-type catalyst, of prochiral aryl methyl ketones under electrochemical conditions to generate the needed BH₃ upon oxidation of NaBH₄ with in situ generated I₂ in the anode compartment. Therefore, various electrochemical parameters were optimised to conduct the desired formation of the chiral secondary alcohols in high to quantitative yields with a high stereochemical induction, although the catalyst loading had to be chosen relatively high to concur with the racemic reduction of the ketones by the electrogenerated BH₃.