2H-Chromenes (2H-1-benzopyrans) are a vitally important class of flavonoid compounds, which are present in a vast number of natural products and pharmaceutically active molecules. For example (Figure 1), Lonchocarpin 1, which has significant antiplatelet effects, was isolated from the ether extract of the seeds and roots of Lonchocarpus Scericeus. Quercinol 2, isolated from the wood-rotting fungus Daedalea quercina (Oak Mazegill), has in vitro anti-inflammatory activity against the enzymes cyclooxygenase 2 (COX-2), xanthine oxidase (XO), and horseradish peroxidase (HRP). Rottlerin 3 (mallotoxin) is a highly functionalized 2H-chromene-based natural product isolated from the Asian tree philippensis Mallotus. Rottlerin displays strong inhibition toward the protein kinase Cdelta (PKCdelta). Recently, Mao and co-workers were able to synthesize 6-bromo-8-ethoxy-3-nitro-2H-chromene 4 that exhibited potent antiproliferative activities against a panel of twelve tumor cell lines. In addition to their biological applications, 2H-chromene derivatives are also valuable intermediates in organic synthesis and have been widely used as photochromic materials. Consequently, many efforts have been made to develop efficient synthetic methodologies to access functionalized 2H-chromene derivatives. One of the most important aims within modern organic synthesis is to develop new highly efficient single-step methods for the preparation of diverse molecules, methods that benefit from simple, inexpensive, and readily available starting materials. Intramolecular cyclization reactions are particularly important tools for the construction of synthetically challenging heterocycles, allowing the generation of at least one ring in a single step with high atom economy. In connection with our series of review

中文翻译：

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从芳基炔丙基醚中制备功能化 2H-Chromenes 的简便且有前景的合成策略。回顾

2H-Chromenes (2H-1-benzopyrans) 是一类极其重要的类黄酮化合物，存在于大量天然产物和药物活性分子中。例如（图 1），从 Lonchocarpus Scericeus 种子和根的醚提取物中分离出具有显着抗血小板作用的 Lonchocarpin 1。Quercinol 2 从木材腐烂真菌 Daedalea quercina (Oak Mazegill) 中分离出来，在体外对环氧合酶 2 (COX-2)、黄嘌呤氧化酶 (XO) 和辣根过氧化物酶 (HRP) 具有抗炎活性。Rottlerin 3 (mallotoxin) 是一种高度功能化的基于 2H-色烯的天然产物，从亚洲树 philippensis Mallotus 中分离出来。Rottlerin 对蛋白激酶 Cdelta (PKCdelta) 显示出强烈的抑制作用。最近，毛和同事能够合成 6-bromo-8-ethoxy-3-nitro-2H-chromene 4，它对一组十二个肿瘤细胞系表现出有效的抗增殖活性。除了生物应用外，2H-色烯衍生物也是有机合成中有价值的中间体，已被广泛用作光致变色材料。因此，已经做出了许多努力来开发有效的合成方法来获得功能化的 2H-色烯衍生物。现代有机合成中最重要的目标之一是开发新的高效单步方法来制备各种分子，这些方法受益于简单、廉价且易于获得的起始材料。分子内环化反应是构建具有合成挑战性的杂环的特别重要工具，允许在单个步骤中以高原子经济性生成至少一个环。与我们的系列审查有关