BF₃·Et₂O controlled selective synthesis of α-substituted propargylamides and β-(<i>N</i>-acylamino) ketones: application to carbon and sulphur nucleophiles

This study presents a metal-free and selective synthesis of α-substituted propargylamides and β-(<i>N</i>-acylamino) ketones utilizing nitriles, aldehydes, and terminal alkynes, mediated by BF₃·Et₂O. The unique reactivity of BF₃·Et₂O, a potent Lewis acid, facilitates precise control over product formation. By adjusting the concentration of BF₃·Et₂O, we can effectively manipulate reaction pathways and selectivity, ensuring the desired products are achieved with enhanced specificity. Notably, this method demonstrates remarkable tolerance to other nucleophiles, such as β-naphthol, indole, arenes and thiol, thereby enabling the synthesis of a diverse array of functionally significant compounds. This approach offers a valuable tool for advancing synthetic methodologies in organic chemistry.