Compounds of the formula I in which R, R1 and R3 have the meanings indicated in Claim 1, are inhibitors of pyruvate dehydrogenase kinase (PDHK), and can be employed, inter alia, for the treatment of diseases such as cancer.本發明提供一種式I化合物,其中R、R1及R3具有申請專利範圍請求項1中指示之含義,其係丙酮酸鹽脫氫酶激酶(PDHK)之抑制劑,且尤其可用於治療諸如癌症等疾病。