Quantum chemical characterization of cycloaddition reactions between the hydroxyallyl cation and dienes of varying nucleophilicity
Quantum chemical characterization of cycloaddition reactions between the hydroxyallyl cation and dienes of varying nucleophilicity
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DOI：
10.1021/jo9806005
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发表时间：
1998-08-07
影响因子：
3.6
通讯作者：
Barrows, SE
中科院分区：
文献类型：
--
作者：
Cramer, CJ;Barrows, SE
羟基烯丙基阳离子更倾向于与二烯以逐步方式进行环加成反应。正电荷分布的分析后形成的中间体初始C-C键的形成提供了一个简单的统一的方法合理化的反应性作为二烯亲核性的函数的变化。预测的产物分布与实验研究结果一致。有趣的是，对于由1，3-丁二烯产生的初始中间体，[3 + 2]环加成反应是有利的，但是作为第二步的闭合以形成C-O键导致中间体可以经历a.低能量Claisen重排形成与紧凑[4 + 3]环加成预期相同的七元环产物。
Hydroxyallyl cation prefers to undergo cycloaddition reactions with dienes in a stepwise fashion. Analysis of positive charge distribution in the intermediate formed after initial C-C bond formation provides a simple unifying method for rationalizing changes in reactivity as a function of diene nucleophilicity. Predicted product distributions are consistent with results from experimental studies. Interestingly, for the initial intermediate generated from 1,3-butadiene, [3 + 2] cycloaddition reactions are favored, but closure to form a C-O bond as the second step results in an intermediate that can undergo a. low-energy Claisen rearrangement to form a seven-membered-ring product identical to that expected from compact [4 + 3] cycloaddition.