摘要:
Titanium imido complexes [Ti(NR)((N2Npy)-N-Ar)(L)](N(2)AN(py) = MeC(2-C5H4N)(CH2NAr)(2), Ar = 4-C6H4Me or 3,5-C6H3Me2) have been prepared from the corresponding bis(amide) complexes [Ti((N2Npy)-N-Ar) (NMe2)(2)]. The reaction chemistry of the imido ligand has been investigated with aryl acetylenes, affording the { 2 + 2} cycloaddition products [Ti((N2Npy)-N-Ar){kappa(2)-N('Bu)CH=CAr'}] (Ar'= Ph and 4-C6H4Me) which represent a catalytic intermediate in the anti-Markovnikov hydroamination of terminal alkynes. Reaction of these azatitanacyclobutene complexes with tert-butylamine completes the catalytic cycle, affording trans-cinnamyl(tert-butyl)amine; conversely, reaction with a second equivalent of alkyne afforded a second insertion product, an azatitanacyclohexadiene [Ti(N2Npy){kappa(2)-N('Bu)CH=C(Ar')C(Ar') = CH}], two examples of which have been characterized by X-ray crystallography. Studies into the catalytic hydroamination of phenyl acetylene with tert-butylamine have been performed and indicate that the formation of an azatitanacyclohexadiene complex represents a deactivation pathway in this catalytic reaction.