Photoinduced Three‐Component Difluoroamidosulfonylation/Bicyclization: Regioselectivity Synthesis of Seven‐Membered Dibenzosultams

Abstract

A mild and safe photochemical methodology has been developed to access difluoroamidosulfonylated dioxodibenzothiazepines via three‐component radical bicyclization cascades. This photocatalyst‐free transformation avoids cumbersome photocatalyst removal procedure and potential toxicity. Mechanistic experiments reveal the generation of an electron donor‐acceptor (EDA) complex in the reaction process. Moreover, synthetic value of the protocol is further demonstrated by gram‐scale reaction, conversion of product and total synthesis of antidepressant drug.

Photochemical difluoromethylation of alkynes: synthesis of CF2H-substituted seven-membered dioxodibenzothiazepines and dibenzazepines

“…Based on the above experimental results and the related literature, 1 a ,7 b ,17,18 a plausible mechanism for this photoinduced difluoromethylation/cyclization of alkynes with NaSO 2 CF 2 H is proposed (Scheme 5). First, the photocatalyst eosin Y is excited to eosin Y* under the irradiation of visible light.…”

“…17 Zhong and Yu groups have described a mild photoinduced approach for the synthesis of difluoroalkylated and difluoroamidosulfonylated dioxodibenzothiazepines via radical cascade cyclization of alkynes, respectively (Scheme 1B). 18 Furthermore, Xu, Li, and Zhong et al have reported an electrochemical or photocatalytic radical cyclization of alkynes to access diverse functionalized seven-membered dibenzazepines, which are another class of core scaffolds in many biologically active molecules. 19 Despite these achievements, the known methods have some limitations such as the requirement of stoichiometric transition-metal catalysts, expensive photocatalysts or high temperatures.…”

Recent Advancements in Metal‐Catalyst‐Free Multicomponent Radical Sulfonylation of Alkynes

“…The carbosulfonylation has attracted attention, with an exemplary contribution from Yu and colleagues (Scheme 10). [20] They reported a visible‐light‐promoted strategy that can access to difluoroamido‐sulfonylated dioxodibenzothiazepines ( 29 ) via three‐component radical bicyclization cascades. As depicted in Scheme 10, combing DABCO with N ‐allylbromodifluoroacetamides generates electron donor‐acceptor (EDA) compounds which proved by ultraviolet‐visible (UV‐vis) spectroscopic measurements.…”