Question

I can't figure out a reaction mechanism for this sequence. My professor says in the presence of a base (NaOtBu), deprotonation of β-indolylketone gives a carbanion. This is followed by the electrophilic attack of elemental sulfur to form a β-indolylketone sulfur species. After the elimination of elemental sulfur (Sn−1), the intermolecular nucleophilic cyclization occurred at the 2-position of the indole ring due to the indole C−H bond activity. Finally, the desired thienoindole was released by oxidative aromatization. So, one of the by products of this reaction is H2S.

Ar2 Ar3 Ar2 NaOt-Bu DMSO S8 Ar1 Ar3 N2, 120 OC, 24 h Ar1 S ZI о ZI

Answer 1

Sg structure HH SH on) ови Naotlu Oxidation S7H