N. Tajima et al., Biomimetic intramolecurar cyclization of 1-trimethylacetyl-3-(3-methanesulfonoxybutyl) indole derivative at the 4-position of indole nucleus, HETEROCYC C, 6(2), 2000, pp. 143-146
1-Trimethylacetyl indole derivative 4c was regioselectively cyclized in 54%
yield at the 4-position of indole nucleus to afford dihydrobenz[c,d]indole
3b.