Enantioselective synthesis of the C-14 to C-5 cyclopentane segment of jatrophane diterpenes
摘要:
The enantioselective synthesis of the C-14 to C-5 cyclopentane segment of jatrophane diterpenes is reported. An Evans aldol addition, a Horner-Wadsworth-Emmons olefination and a thermal intramolecular carbonylene reaction of an alpha-keto ester served as key C/C-connecting transformations. (C) 2003 Elsevier Ltd. All rights reserved.
Synthetic Studies toward Jatrophane Diterpenes from <i>Euphorbia characias</i>. Enantioselective Synthesis of (−)-15-<i>O</i>-Acetyl-3-<i>O</i>-propionyl-17-norcharaciol
作者:Hannes Helmboldt、Martin Hiersemann
DOI:10.1021/jo802581g
日期:2009.2.20
The enantioselective synthesis of (+)-17-norcharaciol is described. An uncatalyzed intramolecular carbonyl-ene reaction and a ring-closing metathesis were used as key C/C-connecting transformations to assemble the trans-bicyclo[10.3.0]pentadecane norditerpenoid core. We also report the evolution of our synthetic strategy toward the fully substituted characiol skeleton and the experiences from this venture.
Synthesis of the Norjatrophane Diterpene (−)-15-Acetyl-3-propionyl- 17-norcharaciol
[reaction: see text] A scalable enantioselective synthesis of the nonnatural 17-norjatrophane diterpene 3-propionyl-15-acetyl-17-norcharaciol is described. Key C/C-connecting transformations are an Evans aldol reaction, an intramolecular carbonyl ene reaction, a Horner-Wadsworth-Emmons olefination, and a ring-closing metathesis for the formation of a 12-membered carbacycle.
The enantioselective synthesis of the C-14 to C-5 cyclopentane segment of jatrophane diterpenes is reported. An Evans aldol addition, a Horner-Wadsworth-Emmons olefination and a thermal intramolecular carbonylene reaction of an alpha-keto ester served as key C/C-connecting transformations. (C) 2003 Elsevier Ltd. All rights reserved.