Selective Synthesis of Unsaturated Imines via [py₂TiI₂(NPh)]₂-Catalyzed Alkyne Carboamination

Strongly Lewis-acidic titanium imido iodide complexes catalyze selective inter- and intramolecular carboamination of alkynes to give unsaturated imines. Computations and mechanistic experiments indicate that unsaturated imines are not necessarily the direct products of alkyne carboamination, as previously reported, but may also result from the ring-opening rearrangement of cyclopropylimines. Reactions of the cyclopropylimine products with titanium iodide complexes confirm that the generation of acyclic imines can occur from an iminocyclopropane rearrangement.