Gold catalysis isomerization

The reaction of allenic ketones 6.205 with a gold(lll) catalyst proved to give a much faster reaction than with silver catalysts, to give substituted furans, 6.206 and 6.207 (Scheme 6.70). In the products, a second molecule of the substrate adds to the initial product, to give 2,5-disubstituted fiiran. Interestingly, palladium(II) catalysis, also slower than gold catalysis, gives the isomeric series of products 6.208. 

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