The utility of gold complexes for homogeneous catalysis has been received much attention because of their soft carbophilic nature, which can activate unsaturated C-C bonds toward nucleophilic attack. In the case of hydroamination, the formal addition of an N-H bond across an unsaturated C-C bond, the attack of a nitrogen nucleophile has been achieved not only to reactive alkynes but also to less reactive allenes and simple olefins very recently. Despite much success to activate unsaturated C-C bonds, the nitrogen nucleophile has been limited in reactive sulfonamides, carbamates, and arylamines. The intermolecular hydroamination with aliphatic amines is so far difficult, although the intramolecular version with aliphatic amines is known. Herein, we report that the intermolecular hydroamination of the allenes 1 with the aliphatic amine 2 (morpholine) takes place by using the cationic gold(I) catalysts 4 in toluene to give the corresponding allylic amines 3 in high to moderate yields. Furthermore, we uncovered that the steric effect rather than electronic effect of PAr3 in 4 is important for enhancing the yield of 3 in this reaction.
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