Gold-catalyzed cyclization of propargylic diynes: Ethers vs acetates – Related products but different pathways

• Propargylic ethers instead of propargylic acetates can react in gold catalysis.
• α-Naphthols can conveniently be obtained this way.
• The new product type probably is generated by a new mechanistic pathway.

Diyne substrates bearing one propargylic ether instead of the previously published propargylic acetates were subjected to a gold catalyst. α−Naphthol derivatives were obtained as products of the cycloisomerization. The close relationship of the products to the corresponding cyclizations implicated a related mechanistic scenary at first, but further studies favour a mechanistic pathway that is completely different.

Diynes with an alkoxy substitution in propargylic position deliver α-naphtholes via a cycloisomerization that is most probably initiated by a nucleophilic attack of the tert-butyl alkyne.Figure optionsDownload as PowerPoint slide