Evidence is presented which supports an earlier suggestion that the linkageposition in a reducing disaccharide may be determined readily by lead tetraacetate oxidation. Compounds examined include alclose and Icetose disaccharides and alclobi~~ronic acids. Two types of reaction-one catalyzed by potassium acetate and the other non-catalyzed-are employed jointly to illustrate oxidation patterns \vhich clearly differentiate each position of the biose linlcage. Partial degradation of reducing disaccharides by lead tetraacetate oxidation is illustrated by the preparation of 2-0-01-and 2-O-8-~-glucopyranosyl-~-erythritol and 4-0-8-D-galactopyra~~osyl-D-erythritol. I n turn, 2-O-~-~-gl~~0pyrall0Syl-~-erythritol is degraded to 2-0-8-D-glucopyranosyl-glycerol.

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From the avocado, a long-known source of D-manno-heptulose and perseitol (D-glycero-D-galacto-heptitol), we have isolated small amounts of D-glycero-D-manno-octulose and D-erythro-o-galacto-octitol, and have obtained strong evidence for the presence a l x of D-talo-heptulose. From Sedum species, a well-known source of sedoheptulose (D-altro-heptulose), we have isolated small amounts of the same o-glycero-o-manno-octulose and also of 8-sedoheptitol (D-g~yCerO-D-glucO-heptitO~~. We have established the structures of the first known naturally occurring octulose and octitol by degradation studies and by the cyanohydrin synthesis from D-glycero-D-manno-heptose.