Dual Incorporation of Trifluoromethyl and Cyano Groups into Pyrazole Pharmcophores via Silver-Catalyzed Cycloaddition Reaction of Trifluorodiazoethane

Silver-catalysed [3 + 2] annulation reaction of aryldiazonium salts with allenes enabled by boronate direction

“…10 We have recently disclosed silver-mediated cycloaddition reactions of trifluorodiazoethane with nitroolefins or alkynes for the synthesis of 4- or 5-substituted 3-trifluoromethylpyrazoles. 11 In the present study, we envisioned that the combination of allenylboronates with a silver catalyst could be capable of generating all-carbon formal 1,3-dipoles, thus holding promise for the subsequent annulation with aryldiazonium salts. 12 The realization of this transformation would further expand the utility of both aryldiazonium salts and allenes in heterocycle synthesis.…”

Direct Access to Trifluoromethylated Benzo[d]oxepines from o-Alkynylaryl Aldehydes and Trifluorodiazoethane

“…6 More recently, the Xu group strategically utilized an o-alkynylated αdiazoketone for the synthesis of functionalized benzo[d]oxepine, and this reaction involves the formation of a ketene intermediate, followed by a nucleophilic attack of indoles/ pyrroles and subsequent O-7-endo-dig cyclization to produce benzo [d]oxepines (Scheme 1b). 7 Evidently, methods that allow the direct preparation of this highly sought-after structural unit are limited. Therefore, methods for constructing benzo[d]-oxepine derivatives from readily available starting materials under mild conditions are highly appealing.…”

“…The intermediacy of the isochromenylium species was first examined. 1-Methylisochromenylium trifluoromethanesulfonate intermediate (7) was synthesized from 1-(2-((4-methoxyphenyl)ethynyl)phenyl)ethan-1-one using the known reaction conditions. 14 The treatment of 7 with trifluorodiazoethane in toluene at 60 °C without any catalyst failed to deliver the desired product suggesting that the addition/ring expansion step requires a catalyst.…”

One-Pot Synthesis of 1-Aryl-3-trifluoromethylpyrazoles Using Nitrile Imines and Mercaptoacetaldehyde As a Surrogate of Acetylene

“…Among the methods available to date, classical condensation of trifluoromethylated 1,3-dicarbonyls or their equivalents with hydrazines is the most often applied strategy to access 3-trifluoromethylpyrazoles. , Also, (3 + 2)-cycloadditions of fluorinated 1,3-dipoles such as 2,2,2-trifluorodiazoethane (CF 3 CHN 2 ) with appropriate dipolarophiles have been shown to be a powerful approach . Importantly, rapid progress in the chemistry of trifluoroacetonitrile imines 1 (Scheme ), recognized as readily available building blocks for the preparation of 3-CF 3 -pyrazoles, has been observed in recent years. , Notably, application of this 1,3-dipole, readily accessible in situ via base-mediated dehydrohalogenation of the respective hydrazonoyl halides 2 , leads to N-functionalized heterocycles and typically offers excellent control on regio- and chemoselectivity of the cycloaddition step.…”