Madelung Synthesis

W. Madelung, Ber. 45, 1128 (1912).

Formation of indole derivatives by intramolecular cyclization of an N-(2-alkylphenyl)alkanamide by a strong base at high temperature:

R. K. Brown in The Chemistry of Heterocyclic Compounds, A. Weissberger, Ed., Indoles, Part I, W. J. Houlihan, Ed. (Wiley, New York, 1972) pp 385-396; W. J. Houlihan et al., J. Org. Chem. 46, 4511, 4515 (1981). Under mild conditions: W. Verboom et al., Tetrahedron Letters 26, 685 (1985); eidem, Tetrahedron 42, 5053 (1986); E. O. M. Orlemans et al., ibid. 43, 3817 (1987).