Unexpected Reactivity of Trifluoromethyl Diazomethane (CF₃CHN₂): Electrophilicity of the Terminal N-Atom

Abstract

After more than 70 years since its discovery, CF3CHN2 was found to possess a novel reactivity mode: N-terminal electrophile. With C-nucleophiles it gives hydrazones that are easily transformed into valuable CF3-heterocycles.

Telescoping Reactions with Trifluorodiazoethane‐Derived Aza‐Wittig Reagents and Allenyl esters

“…Recently,t he groups of Ma [13] and Mykhailiuk [14] reported the electrophilic reactivity of the terminal nitrogen atom of CF 3 CHN 2 with carbon nucleophiles. We were intrigued by the potentialo facomplementary reactivity with other nucleophiles, of which phosphines appeared to be interesting to access de novo aza-Wittig reagents, in line with our aim of using the obtained phosphazenes in reactions with allenyl esters.…”

Iron(III) Porphyrin Catalyzed Olefination of Aldehydes with 2,2,2‐Trifluorodiazoethane (CF3CHN2)

“…The CF 3 CH: carbene is transferred from the metal center to PPh 3 to generate a phosphorene, which undergoes a subsequent Wittig reaction with an aldehyde to lead to the desired CF 3 ‐substituted alkene. On the other hand, the direct combination of PPh 3 with CF 3 CHN 2 readily generates Ph 3 P=N–N=CHCF 3 because of the electrophilicity of the trifluorodiazoethane, and the subsequent reaction with an aldehyde is presumably responsible for the formation of the main azine byproducts (Scheme ). It should be noted that relative to N 2 CHCOOEt, CF 3 CHN 2 has a lower reactivity towards olefination of corresponding aldehydes under similar reaction conditions, and more azine byproducts are formed.…”

“…It is mainly employed in reactions that involve CF 3 CH: carbene insertion, cyclopropanation, dipolar cycloadditions, C ‐nucleophilic addition, C ‐electrophilic addition, and N ‐electrophilic addition reactions. [3c], Surprisingly, the olefination of aldehydes with CF 3 CHN 2 to give CF 3 ‐substituted alkenes has not been reported to date. Inspired by the olefination of carbonyl compounds with ethyl diazoacetate (N 2 CHCOOEt) in the presence of a metalloporphyrin catalyst and considering the similar electronic properties and stability of CF 3 CHN 2 relative to N 2 CHCOOEt, we reasoned that the key ylide intermediate Ph 3 P=CHCF 3 may be directly formed from the reaction of CF 3 CHN 2 with PPh 3 in the presence of an appropriate metalloporphyrin catalyst.…”

Use of trifluoroacetaldehyde N-tfsylhydrazone as a trifluorodiazoethane surrogate and its synthetic applications

“…Trifluorodiazoethane (CF 3 CHN 2 , also known as trifluoromethyldiazomethane) is a highly reactive trifluoromethylating agent employed in transformations such as cycloadditions 1–6 , X–H insertions 7,8 , coupling reactions 9,10 and homologations (Fig. 1a) 11,12 .…”