A concise method for the facile construction of 3-methyl-2-substituted benzo[b]furans and 3-methyl-2-substituted benzo[b]thiophenes using low-cost, abundant, and easy-to-use solid calcium carbide instead of flammable and explosive gaseous acetylene as an original alkyne source, o-bromophenyl ethers or o-bromophenyl thioethers as substrates through an intramolecular carbanion-yne cyclization in a 5-exo-dig manner, and subsequent double-bond isomerization is described. The simultaneous formation of two C–C bonds is realized in a one-step route. The wide substrate scope, high yield, and simple workup manipulations are also merits of this method. The synthetic strategy can also be suitable for the gram scale.

中文翻译：

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使用固体碳化钙替代气态乙炔构建 3-甲基-2-取代的苯并[b]呋喃和 3-甲基-2-取代的苯并[b]噻吩


一种使用低成本、丰富且易于使用的固体碳化钙来简便构建 3-甲基-2-取代苯并[b]呋喃和 3-甲基-2-取代苯并[b]噻吩的简明方法以易燃易爆的气态乙炔为原始炔烃源，以邻溴苯醚或邻溴苯硫醚为底物，通过5-exo-dig方式进行分子内碳负离子-炔环化，随后进行双键异构化。两个C-C键的同时形成是通过一步路线实现的。该方法的优点还包括底物范围广、产率高和后处理操作简单。该合成策略也适用于克级。