21 Diosbulbin-B,-Aの立体構造

抄録

Diosbulbin B, C_<19>H_<20>O_6, and A, C_<20>H_<24>O_7, (formerly called bulbiferin B and A) are the furano-norditerpenes obtained from the root tubers of Dioscorea bulbifera L. forma spontanea Makino et Nemoto (Nigakashu, in japanese). They had been tentatively assigned the formulas (1) and (2), but a further investigation of the structures, particularly on the site of the ether linkage, has led to revision of the structures as (6) and (7) in which ether oxygen is attached to C-8 and C-12 and tertiary methyl group is located at C-5. The stereochemistry of B, A and their derivatives has been studied and the configurations shown in formulas (6) and (7) have been proposed for B and A, respectively. N.M.R., O.R.D., and Mass spectral data and other experimental results which support the above structures are presented and discussed.