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.
Constituents of asclepiadaceae plants. XXXV. Component of Marsdenia tomentosa decne. Structure of tomentin and dehydrotomentin.
作者:HIDEO SETO、KOJI HAYASHI、HIROSHI MITSUHASHI
DOI:10.1248/cpb.23.2397
日期:——
Two new polyoxypregnane derivatives, tomentin (12β-O-, 20-O-diacetyltomentogenin) and dehydrotomentin (12β-O, 20-O-diacetylutendin), were isolated from the stem of Marsdenia tomentosa. Dehydrotomentin is a diester possessing the utendin skeleton to be isolated from the Asclepiadaceae plants for the first time. Very characteristic fragment pattern for tomentogenin derivatives was observed in the mass spectrum of tomentin.
Constituents of asclepiadaceae plants. XXXIII. Component of Marsdenia tomentosa Decne. Structure of tomentosin.
作者:HIDEO SETO、KOJI HAYASHI、HIROSHI MITSUHASHI
DOI:10.1248/cpb.23.1552
日期:——
A new polyoxypregnane derivative, tomentosin (12β-O-tigloyl-20-O-acetyl-tomentogenin) was isolated from the stem of Marsdenia tomentosa. Tomentosin is the first example of the diester possessing a tomentogenin skeleton to be isolated from the Asclepiadaceae plant, and it did not undergo any internal acyl migration which occurrs on mild alkaline hydrolysis of C-12β, 20-diester of sarcostin and other polyoxypregnane derivatives.
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.
Seto,H. et al., Chemical and pharmaceutical bulletin, 1976, vol. 24, p. 1552 - 1554