Gold catalysis in organic synthesis: efficient cycloisomerization of alpha-aminoallenes to 3-pyrrolines.

[reaction: see text] The gold(III) chloride-catalyzed cycloisomerization of various alpha-aminoallenes gave the corresponding 3-pyrrolines in good to high chemical yields. An interesting dependence of the chirality transfer and reactivity on the N-protecting group was observed. The 3-pyrrolines are highly useful intermediates for the synthesis of functionalized pyrrolines, pyrrolidines, and other natural products.