Catalytic Intramolecular Hydroamination of Substituted Aminoallenes by Chiral Titanium Amino-Alcohol Complexes

Intramolecular hydroamination of aminoallenes is catalyzed by titanium complexes with a number of chiral amino alcohols. The ring-closing reaction of hepta-4,5-dienylamine at 110 °C with 5 mol % catalyst gives a mixture of 6-ethyl-2,3,4,5-tetrahydropyridine (14−33%) and both Z - and E -2-propenylpyrrolidine (67−86%). However, the ring-closing reaction of 6-methylhepta-4,5-dienylamine at 135 °C with 5 mol % catalyst gives exclusively 2-(2-methylpropenyl)pyrrolidine. The pyrrolidine products are obtained with enantiomeric excesses up to 16%.