and [5 + 2] cycloadditions of quinolinium ylides with alkynes are reported, providing highly functionalized five-membered indolizine derivatives and seven-membered 1,4-oxazepine compounds, respectively, in moderate to excellent yields under mild reaction conditions. Importantly, quinolinium ylides are derived from donor−acceptor diazo compounds, and different types of donor−acceptor diazo compounds exhibit distinct selectivity and reactivity for the reactions. The [3 + 2] cycloadditions involve an unusual 1,3-ester migration process.