Diastereoselective synthesis of antiquorin and related polyoxygenated atisene-type diterpenes
- 作者：Antonio Abad ; Consuelo Agulló ; Ana C. Cuñ ; at ; Ignacio de Alfonso Marzal ; Antonio Gris ; Ismael Navarro ; Carmen Ramí ; rez de Arellano
- 关键词：Diterpene ; Atisane ; Carvone ; Cyclopropane ; Radical cleavage ; Diels– ; Alder reaction
- 刊名：Tetrahedron
- 出版年：2007
- 期刊代码：107_00404020
- 类别：ch
- 出版时间：12 February 2007
- 卷：63
- 期：7
- 页码：1664-1679
- 文件大小：505 K
摘要
A diastereoselective approach to polyoxygenated atisene-type diterpenes starting from (S)-(+)-carvone is described. The key steps used in the preparation of the atisene framework are an intramolecular Diels–Alder reaction, an intramolecular diazoketone cyclopropanation, an endocyclic cyclopropane ring cleavage and the regioselective reduction of an allylic bromide by a low-valent chromium species. The synthesis of natural atisanes antiquorin (1), atis-16-ene-3,14-dione (3), atis-16-ene-2,3,14-trione (8) and 3β-hydroxy-atis-16-ene-2,14-dione (9) following this approach is presented. Also described is the synthesis of 18-hydroxy-atis-16-ene-3,14-dione (5), the structure erroneously assigned to an atisene isolated from the Fijian plant Euphorbia fidjiana. This work shows that the natural atisene isolated from this plant is, in fact, the epimer at C-4 of this compound.