The present invention relates to compounds of the formula (I)wherein R1, R2, R3, R4, R5, X1, X2, X3, X4, n, and k are defined in the description and claims, and pharmaceutically acceptable salts and / or pharmaceutically acceptable esters thereof. The compounds are useful for in the treatment and prophylaxis of diseases which are modulated by LXRα and / or LXRβ agonists, including increased lipid and cholesterol levels, particularly low HDL-cholesterol, high LDL-cholesterol, atherosclerotic diseases, diabetes, particularly non-insulin dependent diabetes mellitus, metabolic syndrome, dyslipidemia, Alzheimer's disease, sepsis, inflammatory diseases such as colitis, pancreatitis, cholestasis / fibrosis of the liver, and diseases that have an inflammatory component such as Alzheimer's disease or impaired / improvable cognitive function.