Bucherer-Bergs reaction Mechanism

Synthesis From Aldehydes and Ketones. Treatment of aldehydes and ketones with potassium cyanide and ammonium carbonate gives hydantoins in a one-pot procedure (Bucherer-Bergs reaction) that proceeds through a complex mechanism. Some derivatives, like oximes, semicarbazones. Iliiosetricarbazones. and others, are also suitable starting materials. 

Taillades J, Rousset A, Lasperas M, Commeyras A. Mechanism of the Bucherer-Bergs reaction. Comparison with the basic hydration of a-aminonitriles. Bull. Soc. Chim. Fr. 1986 4. 650—658. Taillades J, Collet H, Garrel L, Beuzelin 1, Boiteau L, Choukroun H, Commeyras A. Ai-carbamoyl amino acid solid-gas nitrosa-tion by NO/NOx A new route to oligopeptides via a-amino acid Ai-carboxyanhydride. Prebiotic implications. J. Mol. Evol. 1999 48. 638-645. 

SCHEME 10.1 General Bucherer-Bergs reaction and mechanism. 

The Bucherer-Bergs synthesis is of general application to carbonyl compounds, employing potassium cyanide and ammonium carbonate.1,4 Carbonyl derivatives such as semicarbazones, thiosemicarbazones, oximes, azines, phenylhydrazones, imidazolidines, and azomethines also are readily converted directly to the corresponding hydantoins 44 The extent to which the reaction occurs appears unrelated to the hydrolytic stability of the starting material. The proposed mechanism is given in Scheme 1. 

---