Copper-catalyzed deaminative alkynylation of secondary amines with alkynes: selectivity switch in the synthesis of diverse propargylamines

Transition-metal catalyzed C–N bond activation has become one of the most promising bond cleavage and formation methods in organic synthesis. This method is still challenging when precise control over the selected C–N bond cleavage between two different C(sp3)–N bonds in one molecule is required. Herein, we report a time-dependent selective synthesis of two kinds of the propargylamines using the same CuBr2/TBHP catalysis system. Control over the addition of terminal alkynes at different reaction times is essential for the site-selective deamination/alkynylation of secondary amines to obtain the corresponding products in good to excellent yields.