The present invention relates to compounds having the general formula (I) with the definitions of X1-X3, Y1, Y2, L1, R1 and R2 given below and/or solvates, hydrates, esters and pharmaceutically acceptable salts thereof. Furthermore, the invention relates to the use of said compounds for modulating of the Wnt signalling pathway activity and their use as a medicament, preferably for the treatment of cancer.