Disclosed are compounds of the formula I or a stereoisomer, tautomer, or pharmaceutically acceptable salt or solvate thereof, wherein Q is a bond or --N(R.sup.5)--; T is a bond, --O--, --C(O)--; S, --N(R.sup.5)--, or --C(R.sup.6'R.sup.7'); U is a bond or --C(R.sup.6)(R.sup.7)-- Y is C or N; Z is C or N; ring A, including variables Y and Z, is a three to nine membered cycloalkyl, cycloalkenyl, heterocylcyl, heterocyclenyl, aryl, and heteroaryl ring having 0 to 4, preferably 0 to 2, heteroatoms independently selected from the group consisting of O, S, N and --N(R)--, wherein ring A is unsubstituted or substituted with 1 to 5 independently selected R.sup.1 moieties and/or oxo when ring A is cycloalkyl, cycloalkenyl, heterocyclyl or heterocyclenyl; and R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.6, R.sup.7 and R.sup.7' are as defined in the specification; pharmaceutical compositions comprising the compounds of formula I and the method of inhibiting aspartyl protease, and in particular, the methods of treating cardiovascular diseases, cognitive and neurodegenerative diseases.