Ultra‐Fast Continuous‐Flow Photo‐Thiol‐Ene Functionalization of Conformation‐Controlled Cinchona Alkaloids

In this work, we describe ultra‐fast continuous flow photo‐thiol‐ene reactions on cinchona alkaloids derivatives through a control of the reactive conformation in solution. Flow thiol‐ene reactions proceed at 32 °C under light irradiation at 365 nm and require only 2.5 minutes of residence time to reach completion. The short path length of the tubular flow photochemical reactor, which maximizes and homogenizes the photon flux, associated to the fine tuning of the reactive conformation of cinchona alkaloids in solution are the main reasons for the high rates observed. The predominant conformation in solution of cinchona alkaloids was adjusted through the substitution of the hydroxyl group at C9 by a phenyl carbamate function. Ultra‐fast continuous‐flow photo‐thiol‐ene reactions on cinchona alkaloids are possible through a fine control of the reactive conformation in solution. Switching the hydroxyl group at C9 by a phenyl carbamate allows thiol‐ene functionalization of cinchona alkaloids in less than 2.5 minutes with organic thiols at 32 °C ant under light irradiation at 365 nm.