We study the decay D^0→K̅^*0π^- e^+ ν_e, using SU(2)_L ⊗ SU(2)_R chiral perturbation theory for heavy charmed mesons and vector mesons, in the kinematic regime where p_M · p_π/m_M (here M = D^0 or K̅^*0) is much smaller than the chiral symmetry breaking scale, Λ_χ SB ( Λ_χ SB∼ 1 GeV). We present the leading diagrams and amplitude, and calculate the rate, in the region where, to leading order in our calculations, the K̅^*0 is at zero recoil in the D^0 rest frame. The rate thus calculated is

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... in terms of a known form factor and depends on the DD^* π coupling constant g_D of the heavy (charmed) meson chiral perturbation theory Lagrangian. A measurement of the above decay, in the aforementioned kinematic regime, can result in the extraction of an experimental value for g_D, accurate at the level of our approximations, and give us a measure of the validity of approaches based on chiral perturbation theory in studying similar processes.