A general study of aryloxo and alkoxo ligands in the titanium-catalyzed intermolecular hydroamination of terminal alkynes

A general study of the regioselective hydroamination of terminal alkynes in the presence of Ti(NEt2)(4) and different aryloxo and alkoxo ligands is presented. Depending on the ligand the regioselectivity towards the Markovnikov and the anti-Markovnikov addition product can be controlled. The experimentally observed isomer distribution is explained perfectly by detailed theoretical investigations which demonstrate that the regioselectivity is determined by the relative stability of the corresponding alkynetitanium pi complexes. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.