Carbocyclization versus Oxycyclization on the Metal-Catalyzed Reactions of Oxyallenyl C3-Linked Indoles

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• 作者：Benito Alcaide ; Pedro Almendros ; Jos茅 M. Alonso ; Israel Fern谩ndez
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：July 5, 2013
• 年：2013
• 卷：78
• 期：13
• 页码：6688-6701
• 全文大小：600K
• 年卷期：v.78,no.13(July 5, 2013)
• ISSN：1520-6904

文摘

The preparation of previously unknown (indol-3-yl)-伪-allenols and -allenones was accomplished from indole-3-carbaldehydes, through indium-mediated Barbier allenylation reaction taking advantage of the N-(2-pyridyl)sulfonyl group. Metal-catalyzed cyclizations of oxyallenyl C3-linked indoles proceeded in two ways depending on the presence or absence of the N-(2-pyridyl)sulfonyl group. For allenols, gold-catalyzed oxycyclization occurred in the presence of the protecting group; in the absence of the protecting group, palladium- and gold-catalyzed benzannulations operated. On the contrary, under gold catalysis furyl-indoles were obtained as exclusive products from NH-allenones, while 5-endo carbocyclization adducts were the major components starting from N-SO₂py-protected allenones. These cyclization reactions have been developed experimentally, and their mechanisms have additionally been investigated by a computational study.