Mediator-free electrochemical trifluoromethylation: a cascade approach for the synthesis of trifluoromethylated isoxazolines

Abstract

The developed methodology describes an environmentally benign protocol for electro-oxidative CF3-radical generation, followed by cascade cyclization fabricating isoxazoline scaffold from β,γ-unsaturated oxime. Consecutive C−O and C−C bond formations were achieved...

Transition Metal and Base‐Free Electro‐Oxidative Regioselective Trifluoromethylation of Imidazo[1,2‐a]pyridines

“…Gratifyingly, mono-methyl and dimethyl substitution at diverse positions of the pyridine ring provided the desirable products (1-4) in admirable yields. Presumably, all the mono and di-halogen substituted substrates reacted smoothly and exhibited supreme efficacy towards the expected product (5)(6)(7)(8)(9)(10)(11)(12)(13) formation in pleasant yields ranging 71% to 78%. Similarly, strong electron-withdrawing groups like À CF 3 , À CN, À NO 2 and À CO 2 Et on pyridine rings were compatible producing respective products (14-17) in moderate yields (Scheme 3).…”

“…Recently, our group reported an electrochemical method for the trifluoromethylation of β,γ-unsaturated oximes towards the corresponding trifluoromethylated isoxazolines. [12] [a] A. Halder, + S. Imidazo[1,2-a]pyridines, the core of many important drugs like Zolpidem, Zolimidine play a compelling role in pharma industries owing to their numerous bio-activities, such as antiviral, antibacterial, anticancer, antituberculosis, antidiabetic actions; as well as in material industries. [13] Therefore, synthesis [14] and different functionalization [15] of this heterocycle are of great consequence.…”

“…In the last decade, various electrochemical approaches for the CF 3 ‐radical generation [11] have been developed either by anodic oxidation or cathodic reduction of CF 3 precursors, followed by functionalization in a suitable organic framework. Recently, our group reported an electrochemical method for the trifluoromethylation of β , γ ‐unsaturated oximes towards the corresponding trifluoromethylated isoxazolines [12] …”

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

“…It is noted that the electrochemical synthesis of oxazolines containing a trifluoromethyl or sulfonyl group has not been reported. Based on our previous works in organic electrochemistry, herein, we report a simple electrochemical method for the construction of trifluoromethylated and sulfonylated oxazolines by using Langlois’ reagent CF 3 SO 2 Na as the trifluoromethyl source or ArSO 2 NHNH 2 as the sulfonyl source , (Scheme , e).…”

Iodine(iii)-promoted oxidative carbotrifluoromethylation of maleimides with imidazopyridines and Langlois’ reagent

“…3 Specifically, sodium triflinate (CF 3 SO 2 Na), which is known as Langlois’ reagent, is one of the most convenient and cheapest reagents for trifluoromethylation. 4…”