Indolizine (Chemical formula C8H7N) is a heterocyclic aromatic organic compound that is an isomer of indole. The saturated analog indolizidine forms the structural core of a variety of alkaloids such as swainsonine. Indolizine (Chemical formula C8H7N) is a heterocyclic aromatic organic compound that is an isomer of indole. The saturated analog indolizidine forms the structural core of a variety of alkaloids such as swainsonine. The known molar mass of C8H7N is 117.151 g/mol.