Stereoselective nickel-catalyzed cycloisomerization of 1,6-dienes
Stereoselective nickel-catalyzed cycloisomerization of 1,6-dienes
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DOI：
10.1002/adsc.200800104
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发表时间：
2008-05-01
影响因子：
5.4
通讯作者：
Leitner, Walter
中科院分区：
文献类型：
--
作者：
Boeing, Christian;Hahne, Julia;Leitner, Walter
描述了使用基于[Ni(烯丙基)(cod)][BARF]和威尔克氮杂磷烯all(R)-1的催化剂体系进行1,6-二烯的高度立体选择性环异构化。由对称取代的 1,6-二烯形成五元环状产物，获得了高达 91% 的前所未有的高对映体过量率。对于末端位置取代的不对称 1,6-二烯也实现了高化学和区域选择性，再次产生了五元环状产物，产率相当至非常高。环异构化产物依次进行硼氢化以及外亚甲基官能团的氢化。实现了有希望的非对映选择性，并且这些反应序列可以在一锅法中有效地进行。
Highly stereoselective cycloisomerization of 1,6-dienes with a catalyst system based on [Ni(allyl)(cod)][BARF] and Wilke's azaphospholene all(R)-1 is described. Unprecedented high enantiomeric excesses of up to 91% were obtained for the formation of five-membered cyclic products from symmetrically substituted 1,6-dienes. High chemo- and regioselectivities were achieved also for unsymmetrically 1,6-dienes substituted in terminal position leading again to five-membered cyclic products in fair to very good yields. Cycloisomerization products were subjected to sequential hydroboration as well as hydrogenation of the exo-methylene functional group. Promising diastereoselectivities were achieved and these reaction sequences could be efficiently performed in a one-pot procedure.