Synthetic studies on and mechanistic insight into [W(CO)5(L)]-catalyzed stereoselective construction of functionalized bicyclo[5.3.0]decane frameworks.
Synthetic studies on and mechanistic insight into [W(CO)5(L)]-catalyzed stereoselective construction of functionalized bicyclo[5.3.0]decane frameworks.
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DOI：
10.1002/chem.201001003
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发表时间：
2010-09
期刊：
影响因子：
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通讯作者：
Yuji Onizawa;M. Hara;T. Hashimoto;H. Kusama;N. Iwasawa
中科院分区：
文献类型：
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作者：
Yuji Onizawa;M. Hara;T. Hashimoto;H. Kusama;N. Iwasawa
基于[W(CO)(5)(L)]催化的炔烃亲电活性，通过3-硅氧基-1，3，9-三烯-7-炔衍生物的串联环化反应，实现了多种合成有用的功能化双环[5.3.0]癸烷衍生物的立体选择性合成。反应在光照射下顺利进行，不同底物发生环化反应，得到相应的手性中心最多为四个手性中心的双环化合物。硅氧二烯与硅基取代基作为羟基的等价物的反应也具有广泛的普遍性，得到硅基取代的双环[5.3.0]正庚烷，这是非常有用的合成中间体。关于硅烯醇醚部分的立体化学研究表明，形成七元环的反应途径有两种。(Z)-烯醇硅醚的反应是通过顺式二乙烯基环丙烷中间体的COPE重排进行的，而(E)-烯醇硅醚的反应是通过δ位的二烯基钨物种与金属原子的1，4-加成反应进行的。在硅氧二烯衍生物与硅基取代基的反应中，通过改变硅烯醇醚和烯炔基团的几何构型，可以立体选择性地合成所有可能的非对映异构体。
Stereoselective preparation of a variety of synthetically useful functionalized bicyclo[5.3.0]decane derivatives was achieved by tandem cyclization of 3-siloxy-1,3,9-triene-7-yne derivatives based on the electrophilic activation of alkynes catalyzed by [W(CO)(5)(L)]. The reaction proceeded smoothly under photoirradiation, and various substrates were cyclized to give the corresponding bicyclic compounds with up to four chiral centers stereospecifically. Reactions of siloxydienes with a silyl substituent as an equivalent of a hydroxyl group also proceeded with wide generality to afford silyl-substituted bicyclo[5.3.0]decanes, which were highly useful as synthetic intermediates. Stereochemical studies concerning the silyl enol ether moiety suggested that two types of reaction pathway for the formation of seven-membered rings were present. The reaction of (Z)-enol silyl ethers proceeded through Cope rearrangement of cis-divinylcyclopropane intermediates, and that of (E)-enol silyl ethers by 1,4-addition of the dienyl tungsten species at the position δ to the metal atom. In the reactions of siloxydiene derivatives with silyl substituents, all possible diastereomers could be synthesized stereoselectively by changing the geometry of the silyl enol ether and enyne moieties.