Cationic gold(I) complexes with hollow‐shaped triethynylphosphine ligands efficiently catalyzed intramolecular [2+2] cycloaddition of 1,9‐enynes to afford cyclobutene‐fused eight‐membered carbocycles that were difficult to synthesize by other catalytic systems. Various 1,9‐enynes with carbon linkers with or without a fused ring underwent efficient [2+2] cycloaddition with 5 mol% of the Au catalyst bearing the triarylmethyl‐end‐capped triethynylphosphine in CH₂Cl₂ at rt in the presence of MS 4A as an additive. More challenging 1,9‐enyne substrates with fully saturated acyclic carbon linkers underwent eight‐membered ring formation at 60 °C in ClCH₂CH₂Cl in the absence of MS 4A, forming monocyclic 1,3‐dienes as major products.

中文翻译：

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通过金催化的分子内烯炔[2 + 2]环加成反应合成环丁烯融合的八元碳环

具有空心三乙炔基膦配体的阳离子金（I）配合物可有效催化1,9-炔烃的分子内[2 + 2]环加成反应，从而制得环丁烯稠合的八元碳环，这些碳环很难被其他催化系统合成。在室温下，在室温下，在CH ₂ Cl _2中，各种带有碳接头的带有或不带有稠合环的1,9-烯类化合物进行有效的[2 + 2]环加成反应，加入5 mol％的带有三芳基甲基封端的三乙炔膦的Au催化剂。 MS 4A作为添加剂。具有挑战性的具有完全饱和的无环碳连接基的1,9-烯炔底物在缺少MS 4A的情况下于60°C在ClCH ₂ CH ₂ Cl中经历了八元环形成，形成了单环1,3-二烯作为主要产物。