N-Substituted 2,2,2-trifluoroethanimidic acid 1-methylethylidene hydrazides as synthetic blocks for trifluoromethylated nitrogen heterocycles: syntheses and oxidative cyclizations

Trifluoroacetimidoyl halides: a potent synthetic origin

“…A similar approach had been reported by Uneyama and co-workers for the synthesis of diverse trifluoromethylated N-heterocycles. 107 Pace and co-workers realized a conceptually novel and divergent lithium halocarbenoid-mediated mono-or bishomologation reaction to enable the formation of quaternary trifluoromethyl aziridines (Scheme 90). 108 Trifluoroacetimidoyl chlorides were applied as electrophilic imine surrogates to receive the addition of one or two homologating agents.…”

3-Substituted Benzo[e][1,2,4]triazines: Synthesis and Electronic Effects of the C(3) Substituent

“…Synthesis of 3-Halobenzo [e] [1,2,4] turned out to be sensitive to silica gel, and the crude product was best purified by vacuum sublimation. Two other reference compounds were prepared according to literature protocols for similar derivatives: benzo[e][1,2,4]triazine-3-carboxylic acid 35,61 (1f, Scheme 3) and 3-(trifluoromethyl)benzo [e][1,2,4]triazine 32 (1g, Scheme 4) in yields similar to those reported for their analogues. Thus, 2nitroaniline was diazotized and reacted with ethyl 2chloroacetoacetate to yield derivative 3 (Scheme 3).…”

“…24 Another method involves the formation of benzo [e] [1,2,4]triazine ring via oxidative cyclization of the corresponding N-arylbenzamidrazones (method C, Figure 2). 23,31,32 Although the reaction allows for the formation of a wide range of 3-aryl 23 and 3trifluoromethyl-substituted 32 benzo [e] [1,2,4]triazines in moderate yields, the method suffers from demanding synthesis of amidrazones and use of HgO. 23 Another method for the preparation of the benzo [e][1,2,4]triazine ring relies on reductive cyclization of 2-nitrophenylhydrazones, 21,22 2-nitrophenylhydrazono esters, 33 and 2-nitrophenylhydrazides 34 (method D, Figure 2).…”

N-Phenyltrifluoroacetimidoyl Chloride

“…9 In addition, Friedel-Crafts reaction with 2,4di-tert-butyl-phenol affords 2,4-di-tert-butyl-6-(2,2,2-trifluoro-1phenylimino-ethyl)-phenol in good yield. 10 Addition with nitrogen nucleophiles, such as phenylamines, 11 hydrazines, 12 urethanes, 12 acetone hydrazone, 13 and azide, 14 provides the corresponding trifluoroethanimidic derivatives, which are versatile precursors for the preparation of various polynitrogen heterocycles. Hydroxy-acetic acid esters react in the presence of NEt 3 at 50 • C to afford the imino ethers in good yields, which undergo a Wittig-type rearrangement to γ-fluorinated-α-hydroxy-β-iminoesters.…”