Tungsten-Promoted Pyridine Ring Scission: The Selective Formation of η2-Cyanine and η2-Merocyanine Complexes and Their Derivatives

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• 作者：Daniel P. Harrison ; George W. Kosturko ; Vijay M. Ramdeen ; Adam C. Nichols-Nielander ; Sarah J. Payne ; Michal Sabat ; William H. Myers ; W. Dean Harman
• 刊名：Organometallics
• 出版年：2010
• 出版时间：April 26, 2010
• 年：2010
• 卷：29
• 期：8
• 页码：1909-1915
• 全文大小：812K
• 年卷期：v.29,no.8(April 26, 2010)
• ISSN：1520-6041

文摘

Nucleophiles capable of four-electron donation (e.g., anilines, enolates) add to C2 of the N-acetylpyridinium (NAPy) ligand of TpW(NO)(PMe₃)(NAPy)(OTf) and induce a Zincke−Knig-like ring scission to generate 3,4-coordinated acetamidotrienes or 1-azatrienes with 3Z,5E stereochemistry. This ring opening is driven by the enhanced π-acidity of the cyanine, relative to its purported dihydropyridine predecessor, which stabilizes the π-base {TpW(NO)(PMe₃)}. X-ray data of the indoline-derived analogue (2) indicates that metal coordination disrupts the donor−acceptor (i.e., amide−iminium) conjugation in the cyanine ligand. Photolysis of 2 in the presence of indoline liberates a further derivatized cyanine.