Copper-catalyzed oxidative cyclization of 1,5-enynes with concomitant C-C bond cleavage: an unexpected access to 3-formyl-1-indenone derivatives.

A Cu(0)/Selectfluor system-mediated oxidative cyclization of 1,5-enynes with concomitant C-C bond cleavage to access 3-formyl-1-indenone derivatives is described. Preliminary mechanistic investigations disclosed that the C-C bond cleavage involved a novel water-participated oxygen-insertion ß-carbon elimination through double oxycuprations.