Degradation of carbohydrates
1968; Elsevier BV; Volume: 8; Issue: 2 Linguagem: Inglês
10.1016/s0008-6215(00)80152-4
ISSN1873-426X
Autores Tópico(s)Amino Acid Enzymes and Metabolism
Resumo2,3,4,5-Tetra-O-methyl-d-glucose (6) has been found to occur as a mixture of the β-d-septanose form and the acyclic form. In water, the hydrate of the acyclic aldehyde form is present, as well as the anhydrous aldehyde. Glucosidation with methanol in the presence of acid gave first the dimethyl acetal, and then a mixture of the methyl β-d-septanoside and this acetal. The absence, for the α-d-septanose anomer, of conformations having low free-energy explains the exclusive appearance of the β-d anomer. The aldose 6 was degraded, in 2 min at 20°, by a solution of calcium hydroxide to a mixture of the cis- and trans-3-deoxy-d-erythro-hex-2-enoses with two 3,6-anhydroaldoses. The structures of the compounds were ascertained largely by n.m.r. spectroscopy.
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