Intramolecular cycloadditions of cyclobutadiene with olefins.
Intramolecular cycloadditions of cyclobutadiene with olefins.
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DOI：
10.1021/ja0203162
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发表时间：
2002-11
影响因子：
15
通讯作者：
J. Limanto;John A. Tallarico;James R. Porter;Kelli S. Khuong;K. Houk;M. Snapper
中科院分区：
文献类型：
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作者：
J. Limanto;John A. Tallarico;James R. Porter;Kelli S. Khuong;K. Houk;M. Snapper
环丁二烯和烯烃之间的分子内环加成反应可以得到高度官能化的环丁烯产物。反应的结果取决于在环加成反应中连接两个反应伙伴的系绳的性质。未活化的烯烃通过含杂原子的三原子链结与环丁二烯相连，成功地生成了所需的环加成产物，而没有杂原子连接或链结较长的相应底物较不容易发生分子内环加成反应。计算被用来帮助揭示一些影响环加成反应过程的因素。成功的分子内反应通常需要双烯亲和体的电子激活，系链的构象限制，或较慢的氧化方案。一般来说，环丁二烯的分子间二聚反应是与分子内环加成反应竞争的主要过程。
Intramolecular cycloadditions between cyclobutadiene and olefins can provide highly functionalized cyclobutene-containing products. The outcome of the reaction depends on the nature of the tether connecting the two reactive partners in the cycloaddition. Electronically unactivated olefins attached to cyclobutadiene through a three-atom, heteroatom-containing tether yield successfully the desired cycloadducts, whereas the corresponding substrates without a heteroatom linkage or with a longer tether are less prone to undergo the intramolecular cycloaddition. Calculations were used to help uncover some of the factors that influence the course of the cycloaddition. Successful intramolecular reactions usually require either electronic activation of the dienophile, conformational restriction of the tether, or a slower oxidation protocol. In general, a facile intermolecular dimerization of cyclobutadiene is the major process that competes with the intramolecular cycloaddition.