Development of synthetic methods for accessing a variety of functionalized N-heterocyclic compounds is a significant objective in the fields of organic and medicinal chemistry. Because indolizine derivatives containing nitrogens at their ring junction have been found in a number of natural products, pharmaceuticals, and bioactive compounds, the development of expeditious approaches for the construction and functionalization of indolizine derivatives has gained much attention. However, 3-(alkenyl)indolizine derivatives, a vital skeleton for building phosphoinositide 3-kinase inhibitors, have rarely been reported. For this reason, we developed a one-pot synthetic route to 3-(alkenyl)indolizine derivatives via sequential Rh-catalyzed [2 + 1]-cyclopropanation, Pd-catalyzed ring expansion, and oxidation reactions from pyridotriazoles and 1,3-dienes.