Formation of medium-size bridged ring systems via ring-closing metathesis of 2,5-disubstituted-2,3-dihydro-1H-pyrroles
作者:Samantha J. Bamford、Kees Goubitz、Hester L. van Lingen、Tim Luker、Henk Schenk、Henk Hiemstra
DOI:10.1039/a908272g
日期:——
A series of 2,5-disubstituted-2,3-dihydro-1H-pyrroles were prepared via diastereoselective alkylations of sulfone 10. Ring-closing metathesis (RCM), using Grubbs’ catalyst, provided bridged ring systems with newly formed 9- to 12-membered rings in moderate to good yields. The 9-membered ring was formed as a single Z-isomer whereas the 10- to 12-membered rings were formed as mixtures of E- and Z-isomers. It was shown that the minor diastereomer obtained from the alkylation product 11c failed to undergo RCM, illustrating the crucial aspect of substrate conformation.
一系列2,5-二取代-2,3-二氢-1H-吡咯是通过对砜10进行非对映选择性烷基化合成的。使用Grubbs催化剂的环闭合复分解反应(RCM)提供了新形成的9到12元桥环体系,产率从中等到良好。9元环以单一的Z-异构体形式形成,而10到12元环则以E-和Z-异构体的混合物形式形成。结果表明,从烷基化产物11c得到的小量非对映异构体未能进行RCM反应,这说明了底物构象的关键性。