Marschalk Reaction

C. Marschalk et al., Bull. Soc. Chim. Fr. 3, 1545 (1936).

Sodium dithionite reduction of 1-hydroxy- or aminoanthraquinones to their leuco-forms, followed by condensation with aldehydes to yield the 2-alkylated anthraquinones. 2-Hydroxyanthraquinones yield 1-alkylated products:

Scope and limitations: K. Krohn, W. Baltus, Tetrahedron 44, 49 (1988). Synthetic applications: F. Suzuki et al., J. Am. Chem. Soc. 100, 2272 (1978); L. M. Harwood et al., Can. J. Chem. 62, 1922 (1984); M. T. Furlong et al., Synth. Commun. 20, 2691 (1990); N. R. Ayyangar et al., Indian J. Chem. 31B, 3 (1992); K. Krohn, S. Bernhard, J. Prakt. Chem. 340, 26 (1998).