EXPERIMENTAL AND CALCULATED ACTIVATION PARAMETERS FOR RING-OPENING OF THE 1-BICYCLO[1.1.1]PENTYL RADICAL - THE EFFECT OF BRIDGEHEAD SUBSTITUENTS
EXPERIMENTAL AND CALCULATED ACTIVATION PARAMETERS FOR RING-OPENING OF THE 1-BICYCLO[1.1.1]PENTYL RADICAL - THE EFFECT OF BRIDGEHEAD SUBSTITUENTS
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DOI：
10.1021/jo00015a018
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发表时间：
1991-07-19
影响因子：
3.6
通讯作者：
TAYLOR, DK
中科院分区：
文献类型：
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作者：
DELLA, EW;PIGOU, PE;TAYLOR, DK
用实验和分子轨道理论研究了1-双环[1.1.1]戊基、3-戊基-1-双环[1.1.1]戊基和3-甲氧羰基-1-双环[1.1.1]戊基自由基的开环反应。 我们的研究结果表明，母系统1a是非常不愿意环开放，至少26千卡mol-1的能量障碍。 酯-和苯基取代的基团更容易重排，障碍约25和21千卡mol-1，分别。 在这些过程的分子轨道处理中也观察到这种趋势。 根据我们的新数据，现在必须重新考虑以前的报告，其中包括这种类型的激进重排。
Ring opening of the 1-bicyclo[1.1.1]pentyl, 3-pentyl-1-bicyclo[1.1.1]pentyl, and 3-carbomethoxy-1-bicyclo[1.1.1]pentyl radicals has been studied by experiment and by molecular orbital theory. Our results indicate that the parent system 1a is extremely reluctant to ring open, with an energy barrier of at least 26 kcal mol-1. The ester- and phenyl-substituted radicals rearrange somewhat more readily, with barriers of about 25 and 21 kcal mol-1, respectively. This trend is also observed in the molecular orbital treatment of these processes. Previous reports that include radical rearrangements of this type must now be reconsidered in light of our new data.