The reaction between aldehydes or ketones and alkynes –the carbonyl‐alkyne metathesis– constitutes a very useful strategy for the synthesis of a,b‐unsaturated carbonyls. We now demonstrate that iodine is a highly efficient catalyst for both the intra‐ and intermolecular metathesis reaction in very small concentrations (0.1–1 mol%). Our protocol outperforms other catalytic systems, is operationally very simple, cheap, metal‐free, and tolerates a large variety of functional groups (e.g., –CN, –CO2Me, –Br, –OH) at very low catalyst loadings. We can furthermore show that iodine‐catalyzed carbonyl‐alkyne metatheses can be combined with other iodine‐catalyzed reactions in one‐pot procedures to afford larger and more complex molecular structures. Finally, our mechanistic studies indicate that the iodonium ion is the active catalyst under the reaction conditions.

中文翻译：

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碘催化的羰基-炔复分解反应


醛或酮与炔之间的反应——羰基-炔复分解——构成了合成a,b-不饱和羰基的非常有用的策略。我们现在证明，碘在极低浓度（0.1-1 mol%）下是分子内和分子间复分解反应的高效催化剂。我们的方案优于其他催化系统，操作非常简单、便宜、不含金属，并且在非常低的催化剂负载量下可以耐受多种官能团（例如，-CN、-CO2Me、-Br、-OH）。我们还可以证明，碘催化的羰基炔复分解反应可以与其他碘催化的反应在一锅法中结合，以提供更大、更复杂的分子结构。最后，我们的机理研究表明碘鎓离子是反应条件下的活性催化剂。