Graebe-Ullmann Synthesis

C. Graebe, F. Ullmann, Ann. 291, 16 (1896); F. Ullmann, ibid. 332, 82 (1904).

Formation of carbazoles by the action of nitrous acid on 2-aminodiphenylamines, followed by thermal decomposition of the resulting benzotriazoles:

O. Bremer, Ann. 514, 279 (1934); S. H. Tucker et al., J. Chem. Soc. 1942, 500; N. Campbell, B. Barclay, Chem. Rev. 40, 360 (1947); C. C. Colser et al., J. Chem. Soc. 1951, 110; B. W. Ashton, H. Suschitzky, ibid. 1957, 4559; R. A. Abramovitch, I. D. Spenser, Adv. Heterocycl. Chem. 3, 128 (1964). Photo-decomposition: L. K. Mehta et al., J. Chem. Soc. Perkin Trans. 1 1993, 1261. Synthetic applications: A. Molina et al., J. Org. Chem. 61, 5587 (1996); D. J. Hagan et al., J. Chem. Soc. Perkin Trans. 1 1998, 915.