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| 题名: | Mechanisms and Origins of Periselectivity of the Ambimodal [6+4] Cycloadditions of Tropone to Dimethylfulvene |
| 作者: | Yu, PY (Yu, Peiyuan)
Chen, TQ (Chen, Tiffany Q.)
Yang, ZY (Yang, Zhongyue)
He, CQ (He, Cyndi Qixin)
Patel, A (Patel, Ashay)
Lam, YH (Lam, Yu-hong)
Liu, CY (Liu, Ching-Yang)
Houk, KN (Houk, K. N.) |
| 贡献者: | 化學系 |
| 关键词: | DIELS-ALDER REACTIONS
POTENTIAL-ENERGY SURFACE
MOLECULAR-DYNAMICS
TRANSITION-STATES
BIFURCATIONS
SELECTIVITY
REACTIVITY |
| 日期: | 2017-06-21 |
| 上传时间: | 2018-02-21 16:08:13 (UTC+8) |
| 摘要: | The mechanisms and selectivities of the cycloadditions of tropone to dimethylfulvene have been investigated with M06-2X and B3LYP-D3 density functional theory (DFT) calculations and quasi-classical direct molecular dynamics simulations. The originally proposed reaction mechanism (Houk) involves a highly peri-, regio-, and stereoselective [6(F) + 4(T)] cycloaddition of tropone [4 pi] to dimethylfulvene [6 pi], followed by a [1,5] hydrogen shift, and, finally, a second [6 + 4] cycloaddition of tropone [6 pi] to the cyclopentadiene moiety [4 pi]. Paddon-Row and Warrener proposed an alternative mechanism: the initial cycloaddition involves a different [6(T) + 4(F)] cycloaddition in which fulvene acts as the 4 pi component, and a subsequent Cope rearrangement produces the formal [6(F) + 4(T)] adduct. Computations now demonstrate that the initial cycloaddition proceeds via an ambimodal transition state that can lead to both of the proposed [6 + 4] adducts. These adducts can interconvert through a [3,3] sigmatropic shift (Cope rearrangement). Molecular dynamics simulations reveal the initial distribution of products and provide insights into the time-resolved mechanism of this ambimodal cycloaddition. Competing [4 + 2] cycloadditions and various sigmatropic shifts are also explored. |
| 關聯: | JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 卷: 139 期: 24 頁碼: 8251-8258 |
| 显示于类别: | [化學系所] 期刊論文
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