Duff Reaction

J. C. Duff, E. J. Bills, J. Chem. Soc. 1932, 1987; 1934, 1305; 1941, 547; 1945, 276.

Formylation of phenols or aromatic amines with hexamethylenetetramine in the presence of an acidic catalyst. Ortho-substitution is usual; however in the presence of anhydrous trifluoroacetic acid (TFA) regioselective ortho and para substitutions are observed.

L. N. Ferguson, Chem. Rev. 38, 230 (1946); Y. Ogata, F. Sugiura, Tetrahedron 24, 5001 (1968); F. Wada et al., Bull. Chem. Soc. Japan 53, 1473 (1980). Use of TFA: W. E. Smith, J. Org. Chem. 37, 3972 (1972); J. F. Larrow et al., ibid. 59, 1939 (1994); L. F. Lindoy et al., Synthesis 1998, 1029. Cf. Reimer-Tiemann Reaction.