Sodium hypochlorite, Hofmann rearrangement

S)-A(-Carbamoylalanine (26) also undergoes the Hofmann rearrangement to give (S)- -aminoalanine (27), by use of sodium hypochlorite but not hypobromite (equation 15). ... 

Hofmann established a route to higher homologues of aromatic amines by intramolecular rearrangement of /V-alkylated anilines, a reaction that was of great theoretical and technical importance. In 1870, he reported the conversion of an acid amide into an amine, with loss of one carbon. In 1881, he discovered that when the degradation was carried out with sodium hypochlorite or hypobromite, the yields of primary amines were excellent. This is the Hofmann degradation, or reaction, that takes place via formation of isocyanate60. 

The Hofmann, Lossen, and Curtius rearrangements will next be discussed. In the context of this chapter, the Hofmann rearrangements are those in which o-diamides become annelated pyrimidine-2,4-diones through spontaneous closure at the urethane stage (—NHC02H). The reaction conditions usually call for potassium hypobromite (less often sodium hypochlorite solution), in which the diamide is left at 0°C for about 15 hr, after which it is heated at 60°C or 100°C for about 1 hr. Yields tend to be only moderate, except in a few favored cases. 

L-j -Malamidic acid (16) is the penultimate intermediate in the synthesis of (5)-isoserine (17), an amino acid component of several biologically active peptides. Treatment of 16 with sodium hypochlorite in alkaline solution produces 17 (28% yield) via a Hofmann rearrangement [23]. 

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