[J. Am. Chem. Soc.] Multiple Insertion of a Silyl Vinyl Ether by (α-Diimine)PdMe+ Species
[J. Am. Chem. Soc.] Multiple Insertion of a Silyl Vinyl Ether by (α-Diimine)PdMe+ SpeciesAuthors: Changle Chen, Shuji Luo, and Richard F. Jordan*
Web Release Date: September 9, 2008
ASAP J. Am. Chem. Soc., ASAP Article, DOI: 10.1021/ja8056858
Abstract:This paper reports that (α-diimine)PdMe+ species (1) (α-diimine = (2,6-iPr2—C6H3)NCMeCMeN(2,6-iPr2—C6H3)) undergo multiple insertions of CH2CHOSiPh3 (2), ultimately forming Pd allyl products. The reaction of (α-diimine)PdMeCl, [Li(Et2O)2.8][B(C6F5)4] (1 equiv), and 2 (8 equiv) in CH2Cl2 yields [(α-diimine)Pd{η3-CH2CHCHCH(OSiPh3)CH2CH(OSiPh3)Me}][B(C6F5)4] (7-B(C6F5)4) in 83% NMR yield. 7 is formed as a 95/5 mixture of isomers (7a/b), which converts to an equilibrium 40/60 mixture at 23 °C. X-ray diffraction analysis established that the configuration of the kinetically favored isomer 7a is S,S,S (ent-R,R,R), where the descriptors refer to the configurations of the substituted allyl carbon and the side chain methine carbons, respectively. 7b has an R,S,S (ent-S,R,R) configuration and differs from 7a in that the Pd is coordinated to the opposite allyl enantioface. The reaction of (α-diimine)PdMeCl, Ag[SbF6] (1 equiv), and 2 (8 equiv) under the same conditions yields [(α-diimine)Pd{(η3-CH2CHCHCH(OSiPh3)Me)}][SbF6] (8-SbF6) in 90−100% NMR yield. 8 is formed as a 90/10 mixture of isomers (8a/b) that differ in the configuration of the substituted allyl carbon and evolve to a 70/30 equilibrium mixture at 23 °C. These results are consistent with a mechanism involving generation of 1 and insertion of 2 to give (α-diimine)PdCH2CH(OSiPh3)Me+ (4). In the absence of 2, 4 undergoes β-OSiPh3 elimination and allylic C−H activation to give (α-diimine)Pd(η3-CH2CHCH2)+ (6) and Ph3SiOH. In the presence of excess 2, 4 undergoes a second insertion of 2 to form (α-diimine)Pd{CH2CH(OSiPh3)CH2CH(OSiPh3)Me+ (9), which can undergo β-OSiPh3 elimination/allylic C−H activation to form 8, or insert a third equivalent of 2 ultimately leading to 7. Further chain growth is probably disfavored by steric crowding.
Link: [url]http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/asap/abs/ja8056858.html[/url]
Remarks: 在chem8潜水这么长时间，也出来冒个泡。我一开始做early metal的东西，作了两年没有什么大突破。中间差点换实验室，最后受不了了，六个月前求老板让我换个方向。运气不错，就搞出了这个咚咚。所以想对那些一直没有什么大进展的朋友说：好运气总会来的。大家好运气！！！
[[i] 本帖最后由 clchen 于 2008-9-10 01:37 编辑 [/i]] 恭喜 Congratulations! very interesting work! 用这个方法做polyketide类化合物就牛了，
不知道ee怎样？ 顶一个！！！
回复 4# yushouyun 的帖子
ee 倒是很高，我们得到的是100%的RRR产物。只是目前只能插入三个monomer. Eliminaion 太快了。恭喜
恭喜:) 楼主厉害，膜拜一下！ :) 祝贺楼主 :L :L :L :L :L :L :L :lol :lol :lol :lol :lol :lol 恭喜！ 恭喜，这是一个收获的季节阿，最近总能看到捷报，希望我的也能早点发出来！回复 1# clchen 的帖子
congratulation, :victory: :victory: :victory: :victory: 恭喜恭喜，楼主，再次说明坚持就是胜利！ congratulations！ 再次恭喜！想请教几个问题：:)
1）必须用 scavenger 把 complex 1 [(NN)PdMeCl] 的 Cl 弄掉形成 cation [(NN)PdMe] + 才能反应吗？还是仅仅是为了提高插入的选择性？试过 (NN)PdMeBr 或是 (NN)PdMeI 或是 (NN)PdMe(OTf) 吗？
2）试过极性溶剂（像DMF等）吗？
3）膦配体work吗？
4）[(NN)PdMeCl] 的Me换成其他基团work吗？比如Ph等
5）从你们的结果来看，用Ag(SbF6)时趋向于得到二聚产物，[Li(Et2O)2.8][B(C6F5)4]趋向于得到三聚产物，但是实际上两个阴离子 SbF6 比 B(C6F5)4 小，按理来说更有利多聚，而B(C6F5)4可能更会抑制进一步的聚合，是不是因为电子或是其他的原因？
6）用多于8equiv的olefin是不是也只能得到三聚的产物？
7）从来没得到过烯烃的产物吗？像CH2＝CHCH3，CH2＝CHCH2CH(OR)CH3，CH2＝CHCH2CH(OR)CH2CH(OR)CH3，或是 CH2＝C(OR)CH3，CH2＝C(OR)CH2CH(OR)CH3，CH2＝C(OR)CH2CH(OR)CH2CH(OR)CH3，或是ROCH＝CHCH3，ROCH＝CHCH(OR)CH2CH3，ROCH＝CHCH(OR)CH2CH(OR)CH2CH3 这三个系列的烯烃。
8）检测到cation [(NN)PdOR] + 吗？
9）反应过程有Pd(0)形成吗？反应管变黑吗？
10）试过在一定的酸性或是碱性的条件下做这个反应吗？
多谢了！！:) :)
[[i] 本帖最后由 paracyclophane 于 2008-9-10 18:56 编辑 [/i]] 专业不懂，纯粹支持 感谢分享 楼主厉害，膜拜一下
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