Gold-catalyzed cycloisomerizations of enynes: A mechanistic perspective

Homogeneous catalysis by gold is a relatively young area of research that has grown very rapidly in the last 3-4 years. Since excellent comprehensive reviews of gold chemistry have already been published recently, this review will cover gold-catalyzed cycloisomerization reactions of 1,n-enynes in detail, with a focus on their mechanisms. Cyclizations with concomitant addn. of nucleophiles to 1,n-enynes are also covered, as these reactions shed light on the general mechanism of cyclizations of enynes. These reactions are domino-type transformations in which two bonds (C-C/C-X or two C-C) are consecutively formed.