This manuscript is dedicated to Professor David A. Evans.
This manuscript describes transfer hydrogenation of bicyclic nitrogen-containing heterocyclic compounds using the immobilized chiral phosphoric acid catalyst (R)-PS-AdTRIP in batch and continuous flow. A significant improvement in enantioselectivities is achieved in continuous flow with a fluidized bed reactor packed with (R)-PS-AdTRIP when the flow rate is increased from 0.2 mL/min to 2.0–2.5 mL/min. The optimized continuous flow conditions consistently provide 4–6% ee higher selectivity than transfer hydrogenation in batch with 2 mol% of (R)-PS-AdTRIP, and are used to generate multiple chiral products with the same fluidized bed reactor.
Key words
transfer hydrogenation - chiral phosphoric acid - continuous flow - enantioselectivity - heterocycles
