Investigation of $B \rightarrow D^{(*)}\bar D^{(*)}K$ decays with the BABAR detector

Using about 23M $B \overline B$ events collected in 1999-2000 with the BABAR detector, we report the observation of several hundred $B \to D^{(*)}\overline D^{(*)}K$ decays with two completely reconstructed D mesons. The preliminary branching fractions of the low background decay modes $B^0\to D^{*-}D^{(*)0}K^+$ are determined to be ${\cal B}(B^0 \to D^{*-}D^{0}K^+) = (2.8 \pm 0.7 \pm 0.5)\times 10^{-3}$ and ${\cal B}(B^0 \to D^{*-}D^{*0}K^+) = (6.8 \pm 1.7 \pm 1.7)\times 10^{-3}$. Observation of a significant number of candidates in the color-suppressed decay mode $B^+\to D^{*+}D^{*-}K^+$ is reported with a preliminary branching fraction ${\cal B}(B^+\to D^{*+}D^{*-}K^+)= (3.4\pm 1.6\pm 0.9)\times 10^{-3}.$