THE PRESENT INVENTION RELATES TO COMPOUNDS HAVING THE GENERAL FORMULA (I) WITH THE DEFINITIONS OF X, Y, R₁, R₂, R₃, R₄ R₉, AND R₁₀ GIVEN BELOW, AND/OR A SALT OR ESTER THEREOF. FURTHERMORE THE INVENTION RELATES TO THE USE OF SAID COMPOUNDS FOR THE TREATMENT OF ALZHEIMERS DISEASE AND THEIR USE FOR THE MODULATION OF ᵞ-SECRETASE ACTIVITY.