Asymmetric addition of terminal alkynes catalyzed by a transition metal to isatins obviously is an efficient and economic method for the synthesis of 3-alkynyl-3-hydroxy-2-oxindoles. The new dimeric chiral quaternary ammoniums derived from a natural chiral alkaloid, quinine, can be used as cationic inducers of the enantioselectivity for the Ag(I)-catalyzed alkynylation of isatin derivatives under mild conditions. The desired chiral 3-alkynyl-3-hydroxy-2-oxindoles can be obtained in good to high yields with high to excellent enantioselectivites (≤99% ee). A variety of aryl-substituted terminal alkynes and substituted isatins are tolerated in this reaction.

中文翻译：

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奎宁衍生的银手性季铵盐催化靛红衍生物的炔基化

过渡金属催化端炔不对称加成靛红显然是合成3-炔基-3-羟基-2-羟吲哚的一种有效且经济的方法。衍生自天然手性生物碱奎宁的新型二聚手性季铵盐可用作温和条件下 Ag(I) 催化的靛红衍生物炔基化的对映选择性阳离子诱导剂。所需的手性 3-alkynyl-3-hydroxy-2-oxindoles 可以以高产率和高到极好的对映选择性 (≤99% ee) 获得。在这个反应中可以容忍各种芳基取代的末端炔烃和取代的靛红。