The invention relates to compounds of formula (I)wherein R1 to R5, X and X1 to X3 have the meaning as cited in the description and the claims. Said compounds are useful as inhibitors of ZAP-70 for the treatment or prophylaxis of immunological, inflammatory, autoimmune, allergic disorders, and immunologically-mediated diseases. The invention also relates to pharmaceutical compositions including said compounds, the preparation of such compounds as well as the use as medicaments.