An unexpected homologation/dyotropic rearrangement/interconversion/[3+2] cycloaddition cascade reaction of α‐diazoester‐terminated N‐propyl‐substituted isatin derivatives was achieved in the presence of a chiral N,N′‐dioxide/ScIII catalyst. This catalytic manifold allows rapid construction of several classes of dimeric polycyclic compounds with good yields and high levels of diastereo‐ and enantioselectivity