The present invention encompasses compounds of general formula (1)wherein R1 to R3 are defined as in claim 1, which are suitable for the treatment of diseases characterised by excessive or abnormal cell proliferation, and the use thereof for preparing a medicament having the above-mentioned properties.本發明涵蓋通式(1)化合物,其中R1至R3係如請求項1中所定義,其適用於治療特徵在於過度或異常細胞增殖之疾病,及其用於製備具有上述性質之藥劑之用途。