Studies on the constituents of asclepiadaceae plants. XXXVI. Component of Marsdenia tomentosa Decne: Structure of tomentonin, tomentodin and dehydrotomentosin and difference in the reactivity between utendin and tomentogenin diesters on mild alkaline hydrolysis.
Seto,H. et al., Chemical and pharmaceutical bulletin, 1976, vol. 24, p. 2185 - 2190
作者:Seto,H. et al.
DOI:——
日期:——
Scalable C–H Oxidation with Copper: Synthesis of Polyoxypregnanes
作者:Yi Yang See、Aaron T. Herrmann、Yoshinori Aihara、Phil S. Baran
DOI:10.1021/jacs.5b09463
日期:2015.11.4
Steroids bearing C12 oxidations are widespread in nature, yet only one preparative chemical method addresses this challenge in a low-yielding and not fully understood fashion: Schonecker's Cu-mediated oxidation. This work shines new light onto this powerful C-H oxidation method through mechanistic investigation, optimization, and wider application. Culminating in a scalable, rapid, high-yielding, and operationally simple protocol, this procedure is applied to the first synthesis of several parent polyoxypregnane natural products, representing a gateway to over 100 family members.
Studies on the constituents of asclepiadaceae plants. XXXVI. Component of Marsdenia tomentosa Decne: Structure of tomentonin, tomentodin and dehydrotomentosin and difference in the reactivity between utendin and tomentogenin diesters on mild alkaline hydrolysis.
作者:HIDEO SETO、KOJI HAYASHI、HIROSHI MITSUHASHI
DOI:10.1248/cpb.24.443
日期:——
Three new polyoxypregnane derivatives, tomentonin (12β-O-dihydrotigloyl-20-O-acetyltomentogenin), tomentodin (12β-O-cinnamoyl-20-O-acetyltomentogenin), and dehydrotomentosin (12β-O-tigloyl-20-O-acetylutendin), were isolated from the stem of Marsdenia tomentosa DECNE. Dehydrotomentosin underwent an internal acyl migration from C-12β-OH to C-20-OH on mild alkaline hydrolysis to afford a monoester, but tomentonin and tomentodin did not. The remarkable difference in the reactivity between toementogenin and utendin diesters on this condition was discussed. Tomentonin is the first example of a tomentogenin derivative with an ester linking of dihydrotiglic acid or 2-methylbutyric acid isolated from Asclepiadaceae plants.
Studies on the constituents of asclepiadaceae plants. 40. Absolute configurations of tomentogenin and utendin.
作者:HIDEO SETO、KOJI HAYASHI、HIROSHI MITSUHASHI
DOI:10.1248/cpb.24.2457
日期:——
The configuration at C-20 of tomentogenin and utendin was determined as s by means of the circular dichroism experiment of 20-O-o-nitrobenzoyl derivatives. From these results, the absolute configurations of tomentogenin and utendin were determined as 5α-pregnan-3β, 12β, 14β, 17β, 20α-pentol and pregn-5-ene-3β, 12β, 14β, 17β, 20α-pentol, respectively.