Synthesis and Evaluation of Indole‐Based <i>C</i> – <i>N</i> Axially Chiral Triarylmethanes

Synthesis of C–N axially chiral and N , N ‐bis‐tosylated 2‐aminoindole‐based triarylmethanes via 1,6‐conjugate addition of tosyliminoindoles to p ‐quinone methides (PQM) followed by in situ N ‐protection is reported here. The exceptional C–N configurational stability, with rotational barriers in the range 27.5–40.9 kcal/mol, exhibited by these triarylmethanes, is supported by density functional theory (DFT) calculations and corroborated by experimental evidence. While the 1,6‐conjugate addition takes place in DMF at room temperature under base/catalyst‐free conditions, the diaryliminoindolylmethanes are amenable for in situ N ‐protection via alkylation, acylation, and sulfonylation under mild basic conditions. This methodology provides convenient access to a diverse array of 2‐aminoindole and di‐ t ‐butyl phenol‐based triarylmethanes exhibiting C–N atropisomerism, in good to excellent yields.