Switching reaction pathways of trifluoromethylated thiobenzanilides by choice of different oxidative systems

Visible-Light Induced Radical Perfluoroalkylation/Cyclization Strategy To Access 2-Perfluoroalkylbenzothiazoles/Benzoselenazoles by EDA Complex

“…Figure shows six benzothiazoles attached with a trifluoromethyl group at the 2-position, all of which exhibit remarkable pharmacological properties, such as anti-inflammatory, anti-Alzheimer, antibacterial, antitumor, and anticardiovascular disorder properties . Five typical synthetic methodologies previously published concerning the synthesis of 2-trifluoromethyl substituted benzothiazoles are shown in Scheme a–e, including condensation of 2-aminothiophenols with trifluoroacetic acid, which is a traditional method toward 2-trifluoromethyl substituted benzothiazoles, as exampled by Scheme a; transition-metal-catalyzed annulation of trifluoromethylimidoyl chlorides with hydrosulfide hydrate (Scheme b); intramolecular oxidative cyclization of trifluoromethylated thiobenzanilides (Scheme c); Sandmeyer trifluoromethylation as exampled by Scheme d; and photocatalytic CF 3 radical-initiated cascade cyclization by reaction of 2-isocyanoaryl thioethers with Umemoto reagent (Scheme e) . Notably, even though the synthetic methods toward 2-trifluoromethyl substituted benzothiazoles have extensively been explored, while in sharp contrast, the synthetic method toward 2-perfluoroalkyl substituted benzothiazoles has considerably lagged behind.…”

Sodium Sulfite-Involved Photocatalytic Radical Cascade Cyclization of 2-Isocyanoaryl Thioethers: Access to 2-CF2/CF3-Containing Benzothiazoles

“…Because 2-CF 2 /CF 3 -containing benzothiazoles are a special class of benzothiazole heterocycles that exist in several biologically active molecules (Figure ), notable progress has been achieved in the construction of benzothiazoles . However, the direct synthesis of 2-CF 2 /CF 3 -containing benzothiazoles is still sporadically reported, including condensation of o -aminothiophenols with trifluoroacetic acid or difluoroacetic acid (Scheme a), palladium-catalyzed cyclization of thiobenzamides via C–H functionalization, and oxidative cyclization of thiobenzamides with CAN (Scheme b). Recently, Song developed an elegant method for the direct synthesis of 2-fluorinated benzothiazole via copper-catalyzed coupling of BrCF 2 CO 2 Et and 2-isocyanoaryl thioethers starting from 2-aminothioanisole and difluorocarbene (Scheme c) .…”

Synthesis of Fluorinated Amide Derivatives via a Radical N-Perfluoroalkylation–Defluorination Pathway

“…Furthermore, thioamide 5c was efficiently transformed into benzothiazole 10 in 70% yield, via an oxidative cyclization using CAN. 22 The S-phenyl thioimidate 11 could be obtained in 88% yield from 5c by reaction with a diaryliodonium salt (Scheme 6). 23 A proposed mechanism for the defluorinative functionalization is presented in Scheme 7.…”

“…To demonstrate the applicability of our method, amide 3b was reduced by LiAlH 4 into amine 9 in 65% yield. Furthermore, thioamide 5c was efficiently transformed into benzothiazole 10 in 70% yield, via an oxidative cyclization using CAN . The S -phenyl thioimidate 11 could be obtained in 88% yield from 5c by reaction with a diaryliodonium salt (Scheme ).…”