Synthesis of 1-aminoindole derivatives via Rh(iii)-catalyzed annulation reactions of hydrazines with sulfoxonium ylides

Abstract

Rhodium(iii)-catalyzed C–H functionalization followed by intramolecular annulation reactions between hydrazines and sulfoxonium ylides is described.

Ruthenium(II)-Catalyzed Homocoupling of α-Carbonyl Sulfoxonium Ylides Under Mild Conditions: Methodology Development and Mechanistic DFT Study

“…It was generally proposed that the cyclic product was formed by the first generation of an acylmethylation intermediate in similar cascade reactions. (Chen et al, 2018;Hu et al, 2018aHu et al, ,b, 2019Liang et al, 2018;Shi et al, 2018;Xiao et al, 2018;Xie et al, 2018bXie et al, , 2019Xie H. et al, 2018;Xu et al, 2018;Zhou et al, 2018;Cai et al, 2019;Chen P. et al, 2019;Cui et al, 2019;Huang et al, 2019;Lai et al, 2019;Liu et al, 2019;Luo et al, 2019;Lv et al, 2019;Nie et al, 2019;Shen et al, 2019;Wu C. et al, 2019;Zhang et al, 2019Zhang et al, , 2020Wu et al, 2020). Further transformations from IM6 were explored theoretically to confirm whether the acylmethylation intermediate (IM8) is key in the formation of 2a (Figure 2).…”

α-Carbonyl sulfoxonium ylides in transition metal-catalyzed C–H activation: a safe carbene precursor and a weak directing group

“…Liu and co-workers 29 disclosed a new route for the synthesis of 2-aryl indole scaffolds 71 via Rh( iii )-catalyzed C–H activation and cascade annulation of arylhydrazines 70 with sulfoxonium ylides (Scheme 25). A combination of Cp*Rh(OAc) 2 ·H 2 O and Zn(OAc) 2 proved to be an effective catalytic system for the transformation to deliver 2-subtituted indoles in moderate to good yields.…”

Recent Advances in Metal‐Catalyzed C−H Bond Functionalization Reactions of Sulfoxonium Ylides

“…[20] At the same time, Xie and co-workers also published a Rh(III)-catalyzed reaction for the synthesis of Narylindoles from the same substrates under slightly different reaction conditions (Scheme 16). [21] Wu and co-workers synthesized indoles and quinazolines through Rh(III)-complex catalyzed CÀ H activation and annulation of N-arylamides with sulfoxonium ylides by varying the additives. When NaOH was used as an additive, the reaction predominantly followed [4 + 1] annulation approach to afford indole via CÀ H activation, α-elimination of DMSO, migratory insertion of RhÀ C(sp 2 ) followed by RhÀ C(sp 3 ) and protonolysis whereas using CuF 2 /CsOAc as an additive afforded [5 + 1] annulation product, quinazoline via CÀ H activation, α-elimination of DMSO, migratory insertion and reductive elimination with subsequent oxidation (Scheme 17).…”

“… [20] At the same time, Xie and co‐workers also published a Rh(III)‐catalyzed reaction for the synthesis of N ‐arylindoles from the same substrates under slightly different reaction conditions (Scheme 16). [21] …”