Exploiting Photochemical Processes in Multi‐Step Continuous Flow: Derivatization of the Natural Product Clausine C

Abstract

AbstractThe synthesis and derivatization of carbazoles based upon the natural product clausine C has been accomplished using two different two‐step continuous processes. The resulting carbazoles (9 examples, 33–74 % yield) were prepared by means of a continuous flow set‐up integrating a UV‐mediated transformation employing a purple LED reactor (λ=394 nm) as the first step in the multi‐step sequence. The second derivatization step involved cross‐coupling through Pd‐catalyzed Suzuki cross‐coupling or Ni‐catalyzed metallophotoredox cross‐coupling with potassium trifluoroborate salts. The latter represents the first example of using sequential photochemical reactors, at different wavelengths, in a continuous flow process.