Thermal Chemistry of Bicyclo[4.2.0]oct-2-enes
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- 作者：David C. Powers ; Phyllis A. Leber ; Sarah S. Gallagher ; Andrew T. Higgs ; Lynne A. McCullough ; John E. Baldwin
- 刊名：Journal of Organic Chemistry
- 出版年：2007
- 出版时间：January 5, 2007
- 年：2007
- 卷：72
- 期：1
- 页码：187 - 194
- 全文大小：146K
- 年卷期：v.72,no.1(January 5, 2007)
- ISSN：1520-6904
文摘
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tities/deg.gif">C, bicyclo[4.2.0]oct-2-ene (1) isomerizes to bicyclo[2.2.2]oct-2-ene (2) via a formal [1,3]sigmatropic carbon migration. Deuterium labels at C7 and C8 were employed to probe for two-centeredstereomutation resulting from C1-C6 cleavage and for one-centered stereomutation resulting from C1-C8 cleavage, respectively. In addition, deuterium labeling allowed for the elucidation of the stereochemicalpreference of the [1,3] migration of 1 to 2. The two possible [1,3] carbon shift outcomes reflect a slightpreference for migration with inversion rather than retention of stereochemistry; the si/sr product ratio is~1.4. One-centered stereomutation is the dominant process in the thermal manifold of 1, with lesseramounts of fragmentation and [1,3] carbon migration processes being observed. All of these observationsare consistent with a long-lived, conformationally promiscuous diradical intermediate.