Study of Cationic Palladium Complex-Catalyzed Cyclization-Hydrosilylation of α,ω-Diynes

1)利用钯催化的l-炔与三氯硅烷二聚化-硅氢化的研究结果，我们开发了一种阳离子钯配合物，该配合物对分子内二聚化-硅氢化反应，即α，ω-烷的环化-硅氢化反应具有特定的催化活性。因此，我们用典型的三氯硅烷作为添加物，从1,6-庚二炔衍生物及其同源物开始，制备了5,6元（甚至7元）(Z)-1-（三氯硅基）亚甲基-2-亚甲基环烷。为了阐明这一独特反应可能的催化循环，对不对称的1,6-辛二炔进行了环化-硅氢化反应，得到(Z)-1（1'-三氯硅基）乙基-2-亚甲基环戊烷。结果很好地表明，氢钯化发生在末端炔基上，形成乙烯基钯，而乙烯基钯则与内部炔基进行碳钯化，然后与氢硅烷取代，形成所观察到的产物，并很可能再生氢钯作为活性催化剂。值得注意的是，HSiMe_nCl_(3n) （n = 0 - 2）同样适用于这种催化环化-硅氢化反应，而上述1-炔的二聚化-硅氢化反应则不适用。2)以9-氧-1-十二-6,11-二炔为底物，在阳离子钯配合物催化三氯硅烷环化-硅氢化反应中获得了真正意想不到的反应产物。鉴定出的主要产物（75%）是由内炔位点和末端烯烃之间的环化产生的产物，而由普通的分子内炔环化产生的次要产物（25%）是由分子内炔环化产生的。此外，我们还经历了α，ω- alkadine的环化-硅氢化反应通常比相应的α，ω- alkadi炔快得多。结果可能表明，在上述催化循环中，烯烃位点的碳化反应明显强于炔烃位点。因此，合乎逻辑地建议进行任何氢硅化交叉偶联的炔烃与烯烃。少

1)Taking advantage of the findings involving the palladium-catalyzed dimerization-hydrosilylalon of l-alkynes with trichlorosilane, we have developed a cationic palladium complex, which exhibits a specific catalytic activity for an intramolecular dimerization-hydrosilylation, i.e., cyclization-hydrosilylation of α,ω-alkadiynes. Thus, we have prepared 5, 6-membered (or even 7-membered) (Z)-1-(trichlosilyl)methylene-2-mthylenecycloalkanes starting from 1,6-heptadiyne derivatives and their homologs using typically trichlorosilane as an added.In order to elucidate a possible catalytic cycle of this unique reaction, the cyclization-hydrosilylation of unsymmetrical 1,6-octadiyne was carried out to give exclusively, (Z)-1(1'-trichlorosityl)ethylidene -2-methylenecyclopentane. The results well implicate that the hydropalladation takes place at a terminal alkyne site giving a vinylidene-palladium species, the latter, in turn, undergoing the carbopalladation with an internal alkyne site to cycli … More ze, followed by substitution with the hydrosilane to form the observed product and regenerate most probably a hydridopalladium as an acive catalyst. It is worthy of note that HSiMe_nCl_(3n) (n = 0 - 2) are equally applicable to this catalytic cylization-hydroilylation, while this is not the case for the dimerization-hydrosilylation of 1-alkynes mentioned above.2)Truly unexpected reaction product has been obtained when 9-oxa-1-dodecen-6,11-diyne was used as a substrate in the cationic palladium complex-catalyzed cyclization-hydrosilylation using trichlorosilane as an added. The major product (75%) identified was the one arising from the cyclization between an internal alkyne site and a terminal alkene, whereas the minor product (25%) was obtained from the ordinary intramolecular diyne cyclization. Furthermore, we have experienced that α,ω-alkenynes undergo the present cyclization-hydrosilylation generally much faster than the corresponding α,ω-alkadiynes.The results may suggest that, in the above mentioned catalytic cycle, the tale of carbopalladation at the alkene site must clearly be enhanced than that at the alkyne site. Thus, it is logically suggested to conduct any hydrosilylative cross-coupling of alkynes with alkenes. Less