Photochemical intramolecular amination for the synthesis of heterocycles

Abstract

Polycyclic heterocycles can be formed in good to excellent yields via photochemical conversion of the corresponding substituted aryl azides under irradiation with purple LEDs in a continuous flow reactor.

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

“…Following the optimization of the catalyst structure and exploration of scope, the batch reaction conditions were then transferred to continuous flow ( Table 2 ). Initially, an experimental set-up using a previously reported reactor for purple LEDs was selected for the reaction [ 30 – 31 ]. Following injection of the reaction mixture with a target residence time of 60 min, only traces of the desired bromide 2 were observed.…”

Light on the Horizon: Current Research and Future Perspectives in Flow Photochemistry

“…71 In an alternative approach to carbazoles, aryl azides were used as a photochemical reagent allowing access to more complex heterocycles under UV-LED irradiation in a continuous flow reactor. 72 Specifically, the anti-inflamatory Carprofen could be obtained with a residence time of 4h with a 64% of isolated yield (Scheme 12b). Multi-step Continuous-Flow Synthetic Applications involving a…”

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

“…Our group has previously reported the synthesis of complex polycyclic carbazoles via photochemical decomposition of azides. [8] Given the importance of carbazoles as a heterocyclic framework in medicinal chemistry, we recognized that the UVmediated process, which does not require any additional catalysts, reagents or additives, would be ideally suited in a multi-step synthetic sequence. In addition, the photochemical process involved irradiation at 394 nm which was tolerant of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 halogen substitution that could be exploited downstream to derivatize natural product scaffolds.…”

“…Our group has previously reported the synthesis of complex polycyclic carbazoles via photochemical decomposition of azides . Given the importance of carbazoles as a heterocyclic framework in medicinal chemistry, we recognized that the UV‐mediated process, which does not require any additional catalysts, reagents or additives, would be ideally suited in a multi‐step synthetic sequence.…”