| Popis: |
From 3-ketolactose, 3-ketomaltose, 3-ketomaltobionate and 3-ketosucrose the following new disaccharides have been prepared: gulosylglucose, allosylglucose and allosylfructose. Conditions are described in which the 3-keto function was reduced much faster than the hemiacetal group by Raney nickel. The yield of the reduction was 85–90%. The reduction of 3-ketolactose gave lactose and gulosylglucose. The former sugar was eliminated by oxidation with Aerobacter cloacae . Gulosylglucose was purified and crystallized as the monohydrate. The reduction of 3-ketomaltose gave maltose and allosylglucose. Better yields were obtained from 3-ketomaltobionate. Maltose was eliminated with a Paracolobactrum strain. Allosylglucose was prepared as a chromatographically pure syrup. The reduction of 3-ketosucrose gave allosylfructose, which was purified by charcoal chromatography. Arguments in favour of the proposed structures are given. The rare sugar d -allose can now readily be prepared from 3-ketosucrose after reduction with Raney nickel. The resulting mixture of sucrose and allosylfructose was oxidized with a Paracolobactrum strain, which hydrolyzed both disaccharides and oxidized both glucose and fructose, but left d -allose unchanged. The latter sugar was purified and crystallized. |
