Reactions of Diaziridines with Benzynes Give N-Arylhydrazones

Abstract

Reactions of thermally generated benzynes with diaziridines are reported. These trapping reactions follow the same pathway as reported earlier by Heine and coworkers with electron-deficient alkynes. The resulting N-aryl hydrazones were obtained efficiently in a single step. The preference for the mode of addition of the nucleophilic diaziridine nitrogen atom to the more electrophilic benzyne carbon was consistent with what is predicted on the basis of distortion analysis. The feasibility of converting the hydrazone into a Fisher-indole adduct was demonstrated.

New Trends in Diaziridine Formation and Transformation (a Review)

“…The reactions of nucleophilic diaziridines with electrophilic alkynes were established decades ago [83], and by means of the 15 N-labeling experiment, it was shown that the mechanism of the reaction could be assumed to involve the initial addition of an alkylated nitrogen atom (N-monosubstituted diaziridine counterpart) to provide an intermediate that could subsequently undergo ring-opening and proton transfer, resulting in the adduct product [84]. The trapping reaction resulted in thermally generated benzyne species 95a-f with heteroatom-rich diaziridine 96 leading to N-arylated hydrazones 97a-f in a single step, while these could be converted into fused-ring indole derivatives 97c-e in some cases (Scheme 5).…”

“…The direct reaction with acetylacetone was then conducted from the pure resulting N-phenyl diaziridine 98b, allowing pyrazole 100 and adamantanone 101 to be obtained with excellent yields (Scheme 6) [85]. nitrogen atom (N-monosubstituted diaziridine counterpart) to provide an intermediate that could subsequently undergo ring-opening and proton transfer, resulting in the adduct product [84]. The trapping reaction resulted in thermally generated benzyne species 95a−f with heteroatom-rich diaziridine 96 leading to N-arylated hydrazones 97a−f in a single step, while these could be converted into fused-ring indole derivatives 97c−e in some cases (Scheme 5).…”

Recent Advances in the Preparations and Synthetic Applications of Oxaziridines and Diaziridines

“…In 2018, Hoye et al. developed a trapping reaction between thermally generated benzyne 220 and diaziridines 218 for the construction of N ‐arylhydrazones 219 at 85 °C (Scheme 58a) [102] . The method followed the earlier report by Heine et al.…”

“…[101] In 2018, Hoye et al developed a trapping reaction between thermally generated benzyne 220 and diaziridines 218 for the construction of N-arylhydrazones 219 at 85°C (Scheme 58a). [102] The method followed the earlier report by Heine et al with electron deficient alkynes. [103] The conversion of N-arylhydrazone to fisher indole adduct was also demonstrated.…”

Reactions of thermally generated benzynes with six-membered N-heteroaromatics: pathway and product diversity

“…These short-lived, reactive intermediates then participate in myriad intermolecular trapping processes, including three-component reactions (TCRs) 2. In earlier work, we have described a variety of modes of reactivity initiated by the reaction of these electrophilic benzynes with cyclic sulfides,3 tertiary amines,4 aliphatic cyclic amines,5 oxygen-containing heterocycles,6 and alkaloidal natural products 7…”