Solvent-Controlled Intramolecular [2 + 2] Photocycloadditions of -Substituted Enones

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• 作者：Stephanie M. Ng ; Scott J. Bader ; and Marc L. Snapper
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：June 7, 2006
• 年：2006
• 卷：128
• 期：22
• 页码：7315 - 7319
• 全文大小：228K
• 年卷期：v.128,no.22(June 7, 2006)
• ISSN：1520-5126

文摘

The regio- and stereoselectivity of intramolecular [2 + 2] photocycloadditions of 2'-hydroxyenonesare shown to be solvent-dependent. In the presence of aprotic solvents, 2'-hydroxyenones undergophotocycloadditions in a manner consistent with the presence of an intramolecular hydrogen bond betweenthe carbonyl group and the tether's hydroxy functionality. In protic solvents, intermolecular interactionsappear to disrupt the intramolecular hydrogen bond, providing products with complementary diastereoselectivity. If the facial accessibility of the -tethered olefin is limited, the cycloadditions proceed to givehead-to-tail or head-to-head regioisomers, depending on the nature of the solvent employed.