Copper-Catalyzed [2 + 2 + 3] Annulation of 1,6-Enynes with α-Bromo-1,3-Dicarbonyl Compounds: Synthesis of Dihydrooxepines.

Copper-catalyzed [2 + 2 + 3] annulation of 1,6-enynes with α-bromo-1,3-dicarbonyl compounds is described. This reaction provides facile access to seven-membered dihydrooxepines for epidithiodiketopiperazines with two newly formed C-C bonds and one C-O bond.