Gold‐Catalyzed Reactions of 1,5‐ and 1,6‐Enynes with Carbonyl Compounds: Cycloaddition vs. Metathesis

Gold and rings: The gold(I)-catalyzed addition of aldehydes to 1,6-enynes gives 1,3-dienes, by a cycloaddition/fragmentation process. 1,5-Enynes react with aldehydes and ketones by the 5-endo-dig pathway to give the corresponding cycloadducts.