SUSTAINED HIV PROTEASE INHIBITOR

The present invention provides useful compounds for HIV protease inhibitor. A compound represented by formula or its pharmaceutically acceptable salt Formula: wherein ring A is R 4 is -Y-Z, hydrogen atom, halogen, hydroxy and the like, R 5 is hydrogen atom, halogen, hydroxy and the like, R 6 is each independently halogen, hydroxy, carboxy and the like, ring A may be substituted with said R 6 at any substitutable position(s), a is an integer of 0 to 7, ring B is substituted or unsubstituted aromatic carbocyclyl, or substituted or unsubstituted aromatic heterocyclyl, ring C is substituted or unsubstituted aromatic carbocyclyl, substituted or unsubstituted non-aromatic carbocyclyl, substituted or unsubstituted aromatic heterocyclyl, or substituted or unsubstituted non-aromatic heterocyclyl, R 1 is -Y-Z, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl and the like, R 2 and R 3 are each independently -Y-Z or hydrogen atom, provided that at least one of R 1 , R 2 , R 3 and R 4 is a group represented by formula: -Y-Z, Y is a bond, or a spacer of any combination selected from the group consisting of -O-, -S-, -NR 7 -, -C(=O)-, -SO-, -SO 2 -, -NR 7 -C(=O)-, -C(=O)-NR 7 -, -NR 7 -C(=O)-NR 7 -, -NR 7 -C(=O)-O-, -SO 2 -NR 7 -, -NR 7 -SO 2 -, substituted or unsubstituted alkylene, substituted or unsubstituted alkenylene, substituted or unsubstituted alkynylene, substituted or unsubstituted aromatic carbocyclediyl, substituted or unsubstituted non-aromatic carbocyclediyl, substituted or unsubstituted aromatic heterocyclediyl and substituted or unsubstituted non-aromatic heterocyclediyl, R 7 are each independently hydrogen atom, hydroxy, carboxy and the like, and Z is substituted aromatic carbocyclyl, substituted non-aromatic carbocyclyl, substituted aromatic heterocyclyl or substituted non-aromatic heterocyclyl.