HCID 178511198, Verbindung → Carnosine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

In a 1-litre pressure autoclave, a solution of 10.00 g (45.0 mmol) of (5)-2-(cyanoacetylamino)-3-(1H-imidazol-4-yl)propionic acid (prepared according to Example 3) in a mixture of 157 g of conc. NH3/methanol (m/m=3:2) was added to 0.88 g of Rh/C (0.4 mol % pure Rh, based on reactant used). The autoclave was closed and flushed twice with 40 bar of nitrogen and once with hydrogen. The mixture was heated to 90° C. and the autoclave was pressurized with 40 bar of hydrogen. After 3 h at 90° C., the reaction mixture was cooled to room temperature, the autoclave was depressurized and the catalyst was filtered off by filtration. An in-process analysis (HPLC) showed that the reaction solution (147.2 g) contained 6.38% (m/m) carnosine, corresponding to a selectivity of 92% for complete conversion. The reaction mixture was then concentrated in a rotary evaporator to 41.2 g. 124 g of ethanol were added dropwise at room temperature and the flask was stored in a refrigerator overnight. On the next day, the precipitate was filtered off, washed with ethanol and dried in a drying oven at 40° C./20 mbar. 7.96 g (78%) of a slightly greenish solid with a content (HPLC) of 98% (m/m) were obtained.

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