Beckmann Rearrangement; Beckmann Fragmentation

E. Beckmann, Ber. 19, 988 (1886).

Acid-mediated isomerization of oximes to amides. Oximes of cyclic ketones give ring enlargements:



Certain oximes, particularly those having a quarternary anti to the hydroxyl, are likely to undergo the Beckmann fragmentation to form nitriles instead of amides:



Application to steroidal oximes: P. Catsoulacos, D. Catsoulacos, J. Heterocyclic Chem. 30, 1 (1993). Reviews: L. G. Donaruma, W. Z. Heldt, Org. React. 11, 1-156 (1960); R. E. Gawley, ibid. 35, 1-420 (1988); C. G. McCarty in The Chemistry of the Carbon- Double Bond, S. Patai, Ed. (Interscience, New York, 1970) pp 408-439; J. R. Hauske, Comp. Org. Syn. 1, 98-100 (1991); K. Maruoka, H. Yamamoto, ibid. 6, 763-775; D. Craig, ibid. 7, 689-702. Cf. Schmidt Reaction; Tiemann Rearrangement.