Degradation of carbohydrates. I. Isolation of 3-deoxyhexosones

Abstract

The two possible 3-deoxy-D-hexosones were prepared in high yields by the decomposition of diketoseamino acids in dilute aqueous solution at pH 5 and 100 �C. Small amounts of the corresponding epimeric aldoses were also isolated. 1,1'-(Carboxymethylamino)bis-[1-deoxy-D-fructose], the preparation of which has been improved, gave 3-deoxy-D-erythrohexosone which was characterized as the 2,4-dinitro- and 2,5-dichlorophenylosazones and triacetates, and as the 4-nitrophenyl-osazone. The 4-nitro- and 2,4-dinitrophenylosazones were identical with those prepared from 3-deoxy-D-ribohexose. 1,1'-(Carboxymethylamino)bis-[1-deoxy-D-tagatose] yielded 3-deoxy-D-threohexosone characterized as the 2,4-dinitrophenylosazone and triacetate and 2,5-dichlorophenylosazone. Chromatographic evidence suggests that 3-deoxyhexosones are also formed during the decomposition of other substituted 1-amino-1-deoxyketoses. A mechanism for the formation of 3-deoxyhexosones and of the epimeric aldoses from diketoseamino acids is proposed.