Controlling selectivity: from Markovnikov to anti-Markovnikov hydroamination of alkynes

Depending on the catalyst a remarkable control of regioselectivity is achieved for the titanium-catalyzed intermolecular hydroamination of various alkynes. Proper choice of sterically hindered phenol ligands such as 1 and 4 enables a selectivity switch from the Markovnikov to the anti-Markovnikov products from M:anti-M = > 90:10 to > 10:90.