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氧杂环丁烷的开环反应主要包括亲核性开环、亲电性开环、自由基开环、酸催化和还原开环等几大类。本文主要总结了非对称氧杂环丁烷开环反应的区域选择性。非对称氧杂环丁烷开环反应的区域选择性主要受空间效应和电子效应的影响。氧杂环丁烷的开环反应以亲核性开环为主,强亲核性亲核试剂的开环,受空间位阻控制,主要进攻氧杂环丁烷位阻小的氧邻位碳原子;主要进攻2-乙烯基氧杂环丁烷乙烯基的β-位碳原子,发生S_N2’开环反应。只有在酸性条件下,亲核性相对较弱的含氧和卤素亲核试剂才受电子效应控制,主要进攻氧杂环丁烷位阻大的氧邻位碳原子。亲电性开环、自由基开环、路易斯酸催化的开环和钯催化的氢解开环都是在氧杂环丁烷位阻大的氧邻位碳原子一侧开环。希望本文的结论能够为利用氧杂环丁烷开环反应的同行提供一些有价值的信息,促进氧杂环丁烷开环反应的应用。
The ring-opening reaction of oxetane mainly includes nucleophilic ring opening, electrophilic ring opening, radical ring opening, acid catalysis and ring opening reduction. This article summarizes the regioselectivity of unsymmetrical oxetane ring-opening reactions. The regioselectivities of asymmetric oxetane ring-opening reactions are mainly affected by space and electron effects. The ring-opening reaction of oxetane is dominated by nucleophilic ring opening. The ring opening of strong nucleophilic nucleophile is sterically hindered by steric hindrance. Atom; the main attack 2-vinyl-oxetane vinyl β-carbon atoms, S_N2 ’ring-opening reaction. Only under acidic conditions, the nucleophilic relatively weak nucleophilic oxygen and halogen nucleophiles are electronically controlled, mainly attacking the oxygen ortho-carbon atoms with large steric hindrance to oxetane. Electrophilic ring opening, radical ring opening, Lewis acid-catalyzed ring opening and palladium-catalyzed hydrogenolysis ring are both ring-opened on the oxygen ortho-carbon side of the steric hindrance of oxetane. It is hoped that the conclusion of this paper can provide some valuable information for the colleagues who use the ring opening reaction of oxetane to promote the application of oxetane ring opening reaction.