This invention relates to compounds of the formulawherein R1 to R9 are as described below, or to pharmaceutically acceptable salts thereof. These compounds are BACE2 inhibitors and can be used as medicaments for the therapeutic and/or prophylactic treatment of diseases such as diabetes, particularly type 2 diabetes, and other metabolic disorders.本發明係關於下式之化合物:其中R1至R9如下文所述,或係關於其醫藥學上可接受之鹽。該等化合物為BACE2抑制劑且可用作用於治療性及/或預防性治療諸如糖尿病(尤其為2型糖尿病)及其他代謝障礙之疾病的藥物。