Regioselectivities in alkyne activation: synthesis of 2-(bicyclo[3.1.0]hexan-1-yl)furan derivatives by Au-catalyzed cyclization and cyclopropanation

2-Alkynyl-1-cycloalkenecarbaldehydes, in the presence of gold catalysts, undergo aurative cyclization via the 5-exo-dig mode to form Au-carbene intermediates which react with a double bond to form the corresponding cyclopropanes.