Catalytic and 3D-printed reactors: stereoselective in-flow synthesis of chiral active pharmaceutical compounds

Continuous-flow systems have emerged as a powerful technology for performing chemical transformations and have recently attracted attention also for the preparation of chiral APIs (active pharmaceutical ingredients).[1] Recently developed stereoselective transformations performed in chiral organocatalytic reactors under continuous flow conditions will be presented. Both packed-bed and monolithic reactors, either made by silica and/or organic polymers, have been successfully used in metal-free reactions promoted by immobilized enantiopure primary or secondary amines.[2] The possibility to perform organocatalytic reactions in (micro)-mesoreactors and to synthesize in flow-mode chiral intermediates of pharmaceutical interest will be also discussed.[3] On the other hand, 3D-printing technology allows chemists to build devices with high precision and well-defined architecture. Preliminary results of stereoselective catalytic in-flow reactions in 3D-printed reactors will be also briefly highlighted.[4] The combination of these two only partially explored technologies in stereoselective organic synthesis opens new and intriguing possibilities; the fabrication of ad hoc designed reactors and other devices, to perform at best different reactions becomes now feasible and gives new impulse to the use of enabling technologies in the synthesis of complex molecules