We report two new formal cycloaddition reactions between nitrosobenzenes and alkenylgold carbenoids. We obtained quinoline oxides 3 in satisfactory yields from the gold-catalyzed [3+ 3]-cycloadditions between nitrosobenzenes and alkenyldiazo esters 1. For propargyl esters 5, its resulting gold carbenes react with nitrosobenzene to give alkenylimine 8, followed by a [4+ 2]-cycloaddition with nitrosobenzene.