- Silica Support-Enhanced Pd-Catalyzed Allylation Using Allylic Alcohols
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Although allylation using allylic alcohol is an environmentally-friendly method because of water being the sole byproduct in such reactions, allylic alcohol is one of the most difficult allylating agents in Pd-catalyzed allylation of nucleophiles. In this study, we successfully developed a mesoporous silica-supported Pd complex as an efficient catalyst for the allylation of nucleophiles using allylic alcohols as allylating agents. The allylic alcohol is activated by the silanol group on the support surface, which easily undergoes a π-allylpalladium intermediate formation. The catalytic activity of the supported Pd complex was ca. 9 times higher than that of its homogeneous precursor Pd complex. A highest turnover number of 4500 based on Pd was achieved. Various nucleophiles and allylic alcohol derivatives could be used as substrates. Not only the detailed catalyst structure but also the reaction mechanism including the concerted activation of allylic alcohol by the Pd complex and silanol were investigated by several spectroscopic techniques, such as Pd K-edge XAFS, solid-state NMR, and in-situ FT-IR measurements.
- Motokura, Ken,Ikeda, Marika,Kim, Minjune,Nakajima, Kiyotaka,Kawashima, Sae,Nambo, Masayuki,Chun, Wang-Jae,Tanaka, Shinji
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p. 4536 - 4544
(2018/09/21)
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- Structure-dependent selective O- or C-trifluoroethylation of 1,3-dicarbonyls by mesityl(2,2,2-trifluoroethyl)iodonium triflate
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Reaction of [ArICH2CF3][OTf] with structurally diversified 1,3-dicarbonyls and an appropriate base at room temperature gave O-trifluoroethylated products, C-trifluoroethylated products, or a mixture of O- and C-trifluoroethylated products in good yields. The product type was dramatically dependent upon the structure of the starting 1,3-dicarbonyls in this reaction. The cyclic 1,3-diketones exclusively afforded the O-trifluoroethylated products, whereas the acyclic 1,3-diketones, β-keto esters, and malonates selectively or specifically formed the C-trifluoroethylated products. Li2CO3 facilitated the C-trifluoroethylation of acyclic 1,3-diketones and β-keto esters. The reaction proceeded under mild conditions, without pre-activation of 1,3-dicarbonyls and use of strong base, and demonstrated a catalyst-free structure-dependent regioselective trifluoroethylation of 1,3-dicarbonyls by mesityl(2,2,2-trifluoroethyl)iodonium triflate.
- Zhao, Cheng-Long,Yang, Jing,Han, Zhou-Zhou,Zhang, Cheng-Pan
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supporting information
p. 23 - 30
(2017/10/30)
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- Efficient access to: cis -decalinol frameworks: copper(i)-catalyzed borylative cyclization of allene cyclohexanediones
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Cu-catalyzed borylative cyclization of allene cyclohexanediones has been described through a tandem β-borylation and intramolecular allylic addition process, affording borylated cis-decalinols with excellent yields and diastereoselectivities. A good enantioselectivity is also achieved in the asymmetric version. The hemiboronate group in the cyclization products could be subjected to several useful transformations.
- Zhao, Yi-Shuang,Tang, Xiao-Qi,Tao, Jing-Chao,Tian, Ping,Lin, Guo-Qiang
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supporting information
p. 4400 - 4404
(2016/06/06)
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- C-ALLYLATION OF CYCLIC β-DIKETONES IN AN ACIDIC MEDIUM WITH CATALYSIS BY Pd(0)
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A method is proposed for the C-alkylation of cyclic β-diketones by allyl acetate in a weakly acidic medium with Pd(PPh3)4 as catalyst.The method makes it possible to obtain high yields of the corresponding mono- and diallylated products.
- Lapitskaya, M. A.,Pivnitskii, K. K.
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p. 1665 - 1668
(2007/10/02)
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