A new home-made UV reactor for scale-up production of α-hydroxycyclopenteno-aziridines

α-hydroxycyclopenteno-aziridines are a valuable intermediary to achieve aminocyclopentitols, which can lead to important aminocyclopentitol-based drugs (e.g., ticagrelor, neplanocin A and trehazolin). Therefore, it is important to have a gram-scale supply of α-hydroxycyclopenteno-aziridines to pursue the valorization of these compounds.

The α-hydroxycyclopenteno-aziridines can be obtained via photochemical transformation of pyridinium salts. However, batch production has a low productivity (e.g., photo transformation of 1-allyl pyridinium bromide salt, 39.4 mg.h^-1) considering our necessities.

Being a photochemical reaction, scalability is hindered due to the attenuation effect of photon transport, preventing the use of a simple dimension-enlarging strategy for scale-up. Using larger reactors leads to over-irradiation of the reaction, becoming a crucial issue as the reaction times are substantially increased, resulting in the formation of undesired by-products. An elegant solution to this problem is the development of continuous-flow reactors.

In 2018, we developed different continuous flow reactors improving the productivity of the photo transformation of 1-allyl pyridinium bromide salt up to 40.9 mg.h^-1. We hereby present the development of a new home-made UV photochemical reactor with 12 parallel quartz tubes, with 95 cm of irradiation length, and its application on the process intensification of photochemical transformation of pyridinium salts: 1-allyl pyridinium bromide and 1-butyl pyridinium bromide salts.