  It is pointed out that decays of the type $B \to D \bar{D}$ have no
factorizable contributions, unless at least one of the charmed mesons in the
final state is a vector meson. The dominant contributions to the decay
amplitudes arise from chiral loop contributions and tree level amplitudes
generated by soft gluon emissions forming a gluon condensate. We predict that
the branching ratios for the processes $\bar B^0 \to D_s^+ D_s^-$,
  $\bar B^0 \to D_s^{+*} D_s^- $ and $\bar B^0 \to D_s^+ D_s^{-*}$ are all of
order $(3- 4) \times 10^{-4}$, while $\bar B^0 \to D_s^{+*} D_s^{-*}$ has a
branching ratio 5 to 10 times bigger. We emphasize that the branching ratios
are sensitive to $1/m_c$ corrections.
