Electrochemical Trifluoromethylation and Sulfonylation of N-Allylamides: Synthesis of Oxazoline Derivatives

Abstract

We report a new method for the synthesis of trifluoromethylated and sulfonylated oxazolines by electrochemical radical cascade cyclizations of N-allylamides with sodium trifluoromethanesulfinate or sulfonylhydrazines. This protocol provides a green and useful strategy to synthesize trifluoromethylated and sulfonylated oxazolines with a broad substrate scope under ambient conditions.

Cobalt‐Catalyzed Oxytrifluoromethylation of N‐Allylamides toward Trifluoromethyl‐Containing Oxazolines

“…With the optimized reaction conditions in hand, we then examined the substrate scope of this cobalt-catalyzed oxytrifluoromethylation of N-allylamides (Scheme 2). Substrates with various electron-donating (Me, OMe) or electron-withdrawing substituents (CN, NO 2 , CO 2 Me, Cl) were smoothly transformed into the desired oxazolines in good to excellent yields (4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Heterocycle, such as thiophene (14) and furan (15), were well tolerated, too.…”

“…Taken together, the formation of the anticipated CF 3containing oxazolines via a radical-cation crossover mechanism is likely. [11]…”

“…Several trifluoromethylating agents have been employed in this transformation. For instance, Fu [10] and Huang [11] employed the Langlois' reagent NaSO 2 CF 3 in the oxytrifluoromethylation of N-allylamides in the combination of superstoichiometric iodobenzene diacetate PhI(OAc) 2 and under electrochemical conditions, respectively. Xiao [12] and Akita [13] found Umemoto's reagent to be the optimal choice in the photoredox oxytrifluoromethylation of N-allylamides.…”