Here, we present an intriguing photoinduced chloroamination cyclization of allenes bearing a tethered sulfony-lamido group to afford 2-(1-chlorovinyl)pyrrolidines and related heterocycles in the presence of N-chlorosuccinimide (NCS) as the chlorine source. An in depth experimental and computational mechanistic study revealed the existence of multiple reaction pathways leading to a common nitrogen centered radical (NCR). This key NCR can be, in fact, originated from (a) the oxidation of the deprotonated allene by the photoexcited state of the Ru-catalyst and (b) the photodissociation of the in situ formed N-chloroallene. The NCR formation triggers an intramolecular cyclization to a highly reactive pyrrolidine vinyl radical, which upon chlorination delivers the final product. Thus, NCS plays a dual role, serving both as an activator of the sulfonamido functionality and as the chlorinating agent.

Photoinduced Chloroamination Cyclization Cascade with N-Chlorosuccinimide: From N-(Allenyl)sulfonylamides to 2-(1-Chlorovinyl)pyrrolidines

Azzi, Emanuele
First
;
Ghigo, Giovanni;Parisotto, Stefano;Moro, Riccardo;Renzi, Polyssena
;
Deagostino, Annamaria
Last
2023-01-01

Abstract

Here, we present an intriguing photoinduced chloroamination cyclization of allenes bearing a tethered sulfony-lamido group to afford 2-(1-chlorovinyl)pyrrolidines and related heterocycles in the presence of N-chlorosuccinimide (NCS) as the chlorine source. An in depth experimental and computational mechanistic study revealed the existence of multiple reaction pathways leading to a common nitrogen centered radical (NCR). This key NCR can be, in fact, originated from (a) the oxidation of the deprotonated allene by the photoexcited state of the Ru-catalyst and (b) the photodissociation of the in situ formed N-chloroallene. The NCR formation triggers an intramolecular cyclization to a highly reactive pyrrolidine vinyl radical, which upon chlorination delivers the final product. Thus, NCS plays a dual role, serving both as an activator of the sulfonamido functionality and as the chlorinating agent.
2023
88
6420
6433
https://pubs.acs.org/doi/full/10.1021/acs.joc.2c01963
Allenes,Chemical reactions,Cyclization,Irradiation,Pyrrolidines
Azzi, Emanuele; Ghigo, Giovanni; Sarasino, Lorenzo; Parisotto, Stefano; Moro, Riccardo; Renzi, Polyssena; Deagostino, Annamaria
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1879885
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