氧杂环丁烷的扩环反应

Ring Expansions of Oxetanes

氧杂环丁烷是一类重要的小杂环化合物,也是重要有机合成中间体,在有机化学、药物化学和高分子化学中都有广泛的应用.作为具有较大环张力的小杂环化合物,氧杂环丁烷类化合物除可以发生开环反应外,也很容易发生扩环反应,构建含氧普通环到大环化合物.主要总结了氧杂环丁烷的扩环反应,包括重氮化合物作为卡宾前体与氧杂环丁烷的扩环反应、金属催化的分子间环加成和邻基参与的分子内环加成反应及亲核扩环反应等.分析了一些扩环反应的机理,并对扩环反应未来的发展提出了新的展望.

Oxetanes are a class of important small heterocycles and intermediates in organic synthesis and have been widely applied in organic, pharmaceutical and polymer chemistries. As small heterocycles with a large ring tension, oxetanes not only prefer ring-opening reactions, but also favor ring expansions, to construct oxygen-containing common to large heterocyclic compounds. The ring expansion reactions of oxetanes, including the ring expansions with diazo compounds as carbene precursors, the metal catalyzed intermolecular cycloadditions and the intramolecular cycloadditions involving neighboring group participation, the nucleophilic ring expansion and so on are reviewed. Some reaction mechanisms of ring expansion reactions are analyzed, and new prospects for the future development of the ring expansion reactions are put forward.