  Inspired by the potential prospects of high-luminosity dedicated colliders
and the high enthusiasms in searching for new physics in the flavor sector at
the intensity frontier, the ${\Upsilon}(1S)$ ${\to}$ $D^{-}{\pi}^{+}$,
$\overline{D}^{0}{\pi}^{0}$ and $D_{s}^{-}K^{+}$ weak decays are studied with
the perturbative QCD approach. It is found within the standard model that the
branching ratios for the concerned processes are tiny, about ${\cal
O}(10^{-18})$, and far beyond the detective ability of current experiments
unless there exists some significant enhancements from a noval interaction.
