Gold(I)-Catalyzed Intramolecular Dihydroamination of Allenes with N,N′-Disubstituted Ureas To Form Bicyclic Imidazolidin-2-ones

Reaction of N-delta-allenyl urea 1 with a catalytic 1:1 mixture of gold(I) N-heterocyclic carbene complex (5)AuCl [5 = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidine] and AgPF6 at room temperature for 2 h led to isolation of bicyclic imidazolidin-2-one 4 in 93% yield with >= 98% diastereomeric purity. Gold-catalyzed dihydroamination was effective for a number of N-delta- and N-gamma-allenyl ureas to form the corresponding bicyclic imidazolidin-2-ones in good yield with high diastereoselectivity.