Abstract Diels–Alder reactions of 5-methylthio-2-vinyl-1H-pyrroles with maleimides followed by isomerization gave tetrahydroindoles in moderate to good yield. Aromatization using activated MnO 2 in refluxing toluene gave the corresponding 2-methylthioindoles in good yields, and demethylthioation using Raney nickel gave the 2-H indoles in excellent yields. The protection of the adducts produced aromatization in improved yield, demonstrating ...
[Berthiaume, Sylvie L.; Bray, Brian L.; Hess, Petr; Liu, Yanzhou; Maddox, Michael L.; et al. Canadian Journal of Chemistry, 1995 , vol. 73, # 5 p. 675 - 684]