Nickel-Catalyzed Alkylation and Transfer Hydrogenation of 伪,尾-Unsaturated Enones with Methanol

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• 作者：Nahury Castellanos-Blanco ; Marcos Flores-Alamo ; Juventino J. Garc铆a
• 刊名：Organometallics
• 出版年：2012
• 出版时间：January 23, 2012
• 年：2012
• 卷：31
• 期：2
• 页码：680-686
• 全文大小：386K
• 年卷期：v.31,no.2(January 23, 2012)
• ISSN：1520-6041

文摘

Complexes of the type [{(dippe)Ni}_n(畏²-C_伪,C_尾-1,4-dien-3-one)] (dippe = 1,2-bis(diisopropylphosphino)ethane); n= 1, 2; enone = aromatic 1,4-pentadien-3-ones) were synthesized. The 鈥淸(dippe)Ni]鈥?moiety derived from [(dippe)Ni(渭-H)]₂ 畏²-coordinated to the C,C double bonds of the corresponding 伪,尾-unsaturated enone and was fully characterized using a variety of spectroscopic techniques, for instance, single-crystal X-ray diffraction, nuclear magnetic resonance (NMR), and mass spectrometry. The complexes were assessed in a catalytic transfer hydrogenation process using methanol (CH₃OH) as a hydrogen donor. This alcohol turned out to be a very efficient reducing and alkylating agent of 1,4-pentadien-3-ones, under neat conditions. The current methodology allowed the selective reduction of C鈺怌 bonds in 伪,尾-unsaturated enones to yield enones and saturated ketones by a homogeneous catalytic pathway, whereas by a heterogeneous pathway, the process leads to the formation of mono- and dimethylated ketones. In the latter case, the occurrence of nickel nanoparticles in the reaction media was found to participate in the catalytic alkylation of such dienones.