Trimethysilylation and G.L.C.-mass spectrometry of 3-ketoses and 2-heptuloses

Abstract G.l.c.-mass spectrometry of trimethylsilylated d -gluco-3-heptulose, d -manno-3-heptulose, d -ido-3-heptulose, d -arabino-3-hexulose, l -xylo-3-hexulose, d -ribo-3-hexulose, erythro-3-pentulose, l -threo-3-pentulose, d -manno-2-heptulose, d -gluco-2-heptulose, and sedoheptulose was performed. 3-Heptuloses and 3-hexuloses, upon trimethylsilylation with chlorotrimethylsilane-hexamethyldisilazane-pyridine, showed a g.l.c. peak for the open-chain form as the largest component. The open-chain form is presumed to have been produced mainly by opening of the hemiacetal ring during trimethylsilylation, and this transformation is regarded as one of the characteristic properties of 3-ketoses in both furanoid and pyranoid forms. The gas chromatograms of 3-heptuloses were analogous to one other, showing furanoid peaks of shorter retention-times than the other tautomers, a pyranoid peak, and a peak for the open-chain form having the longest retention time (OV-17). The main peak for sedo-heptulose in g.l.c. was shown to be that of the furanoid form. Trimethylsilylation of coriose was also conducted with 1-(trimethylsilyl)imidazole and N,O-bis(trimethylsilyl)acetamide.