Calcium-catalyzed formal [3 + 2] annulation of C,N-diacyliminium ions with nucleophilic phenols: a diversity oriented synthesis of 3-aminofurans.

We have developed a one-pot, three-component, and solvent-free reaction for the synthesis of 3-aminofurans using a calcium catalyst. In this cascade reaction, the key intermediate, C,N-diacyliminium ion, is formed in situ from glyoxal and lactam, which further reacted with phenolic nucleophiles to form furan derivatives in good yields with broad substrate diversity. We also present here the preliminary photophysical studies of selected compounds.