Department of Chemistry and Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
Angew Chem Int Ed Engl. 2017 Sep 11;56(38):11624-11627. doi: 10.1002/anie.201706845. Epub 2017 Aug 10.
Total syntheses of the reported structures of the rhamnofolane diterpene natural products curcusones I and J in racemic form were achieved. The synthetic strategy features a novel tandem gold-catalyzed furan formation and furan-allene [4+3] cycloaddition to build the 5,7-fused ring system with an oxa-bridge in one step, and a stereoselective exo-Diels-Alder reaction to form the 6-membered ring. The newly developed tandem gold catalysis is quite general and can be scaled up. Our syntheses suggest that structural revisions of curcusones I and J are needed.
以非对映异构体形式实现了报道的瑞马烷二萜天然产物 curcusones I 和 J 的结构的全合成。该合成策略的特点是新型串联金催化呋喃形成和呋喃-丙二烯 [4+3] 环加成一步构建具有氧桥的 5,7-稠合环系统,以及立体选择性的 exo-Diels-Alder 反应形成 6 元环。新开发的串联金催化作用非常通用,并且可以放大。我们的合成表明需要对 curcusones I 和 J 的结构进行修订。