Selective Monoterpene-like Cyclization Reactions Achieved by Water Exclusion from Reactive Intermediates in a Supramolecular Catalyst

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• 作者：William M. Hart-Cooper ; Kristen N. Clary ; F. Dean Toste ; Robert G. Bergman ; Kenneth N. Raymond
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：October 31, 2012
• 年：2012
• 卷：134
• 期：43
• 页码：17873-17876
• 全文大小：267K
• 年卷期：v.134,no.43(October 31, 2012)
• ISSN：1520-5126

文摘

A polyanionic supramolecular assembly (1) is shown to catalytically cyclize the monoterpene citronellal and two homologues. In contrast to cyclization in acidic aqueous solution, the hydrophobic interior of 1 prevents the capture of reactive intermediates by water. This effect was also observed in the gold-catalyzed cycloisomerization of an enyne. Due to the steric confinement of the catalyst鈥檚 interior, Prins cyclizations in 1 proceed cleanly both for substrates containing and lacking gem-dimethyl substitution. Encapsulation in 1 consequently imposes a degree of mechanistic control that, similar to enzyme catalysis, is not observed in bulk aqueous solution.