Baeyer-Drewson Indigo Synthesis

A. Baeyer, V. Drewson, Ber. 15, 2856 (1882).

Formation of indigos by an aldol reaction, q.v., of o-nitrobenzaldehydes to acetone, pyruvic acid or acetaldehyde; of interest mainly as a method of protecting o-nitrobenzaldehydes:

K. Venkataraman, Chemistry of Synthetic Dyes 2, 1008 (New York, 1952); M. Sainsbury, Rodd's Chemistry of Carbon Compounds IVB, 346, 353 (1977). Synthetic applications: J. R. Mckee et al., J. Chem. Ed. 68, A242 (1991); L. Fitjer et al., Tetrahedron 55, 14421 (1999).