Studies on the Origin of Dihydrofurans from α-Diazocarbonyl Compounds. Concerted 1,3-Dipolar Cycloaddition vs. Nonsynchronous Coupling in the Copper Chelate Catalyzed Reactions of α-Diazodicarbonyl Compounds with Electron-Rich Olefins

Article abstract of DOI:10.1021/jo00140a030

The copper chelate catalyzed thermolysis of alkyl 2-diazo-3-oxobutyrate (1) and of 3-diazo-2,4-pentanedione (2) in the presence of several vinyl ethers to give 4-(alkoxycarbonyl)- and 4-acyl-2,3-dihydrofurans is used to probe the mechanism of this transfo