Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria-Rio Grande do Sul, Brazil 97105-900.
J Org Chem. 2010 Aug 20;75(16):5701-6. doi: 10.1021/jo101126q.
A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl(3)/diorganyl dichalcogenides intramolecular cyclization, has been developed. Aryl and alkyl groups directly bonded to the chalcogen atom were used as cycling agents. The results revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species. We observed that the pathway of reaction was not sensitive to the nature of substituents in the aromatic ring of anisole since both the electron-donating and the electron-withdrawing groups delivered the products in similar yields. In addition, the obtained heterocycles were readily transformed to more complex products by using a chalcogen/lithium exchange reaction with n-BuLi followed by trapping of the lithium intermediate with aldehydes, furnishing the desired secondary alcohols in good yields.
已经开发出一种从易得的 2-炔基苯并呋喃出发，通过 FeCl(3)/二芳基二硫化物分子内环化来合成 3-杂原子苯并[b]呋喃的通用方法。芳基和烷基直接键合在杂原子上作为环化试剂。结果表明，反应显著依赖于与二硒化物物种硒原子键合的芳环上取代基的电子效应。我们观察到，反应途径对苯并呋喃中与硒原子键合的芳环上取代基的性质不敏感，因为供电子和吸电子基团都以相似的产率提供产物。此外，通过使用硒/锂交换反应与 n-BuLi 进行反应，然后用醛捕获锂中间体，可以很容易地将得到的杂环转化为更复杂的产物，从而以良好的收率得到所需的仲醇。
