Cyclization of 1,6-Enynes Catalyzed by Gold Nanoparticles Supported on TiO2: Significant Changes in Selectivity and Mechanism, as Compared to Homogeneous Au-Catalysis

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• 作者：Charis Gryparis ; Christina Efe ; Christos Raptis ; Ioannis N. Lykakis ; Manolis Stratakis
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：June 15, 2012
• 年：2012
• 卷：14
• 期：12
• 页码：2956-2959
• 全文大小：261K
• 年卷期：v.14,no.12(June 15, 2012)
• ISSN：1523-7052

文摘

Gold nanoparticles supported on TiO₂ (1.2 mol %) catalyze, for the first time under heterogeneous conditions, the cycloisomerization of a series of 1,6-enynes in high yields. In several cases, the product selectivity differs significantly as compared to homogeneous Au(I)-catalysis. Based on product analysis and stereoisotopic studies it is proposed that the major or exclusive pathway involves a 5-exo cyclization mode to form stereoselectively gold cyclopropyl carbenes that undergo a single cleavage pathway, in contrast to homogeneous Au-catalysis where the double cleavage pathway operates substantially.