Towards NNLO corrections in B --> D pi

We describe the status of the calculation of the branching ratio for the decay \bar B^0 --> D^+ pi^- to NNLO in QCD factorization. Here, we present the result for the colour-singlet hard-scattering kernel. The calculation has been performed using multi-loop techniques like Laporta's reduction to master integrals, and Mellin-Barnes representations and differential equations for evaluating the latter.