BF·EtO-promoted unconventional reactions of 2-oxoaldehyde: access to 4-amidooxazoles and β-keto amides/sulphonamides.

This study investigates the potential of boron trifluoride etherate (BF·OEt) to trigger unprecedented reactions of 2-oxoaldehydes with nitriles and amides/sulphonamides. In contrast to the mechanism in conventional reactions, the α-carbonyl group in 2-oxoaldehydes induces a cyclization pathway to be followed when reacting with nitriles, yielding 4-amidooxazoles. Additionally, reactions with weak nucleophiles produce β-keto amides/sulphonamides. BF·OEt catalysis offers a novel, efficient, and operationally simple synthetic route to these valuable compounds, showcasing the versatility of boron Lewis acids in organic transformations.