Cyclic HIV protease inhibitors: design and synthesis of orally bioavailable, pyrazole P2/P2' cyclic ureas with improved potency.

Highly potent HIV-1 protease (HIVPR) inhibitors have been designed and synthesized by introducing bidentate hydrogen-bonding oxime and pyrazole groups at the meta-position of the phenyl ring on the P2/P2' substituents of cyclic ureas. Nonsymmetrical cyclic ureas incorporating 3(1H)-pyrazolylbenzyl as P2 and hydrophilic functionalities as P2' show potent protease inhibition and antiviral activities against HIV and have good oral bioavailabilities. The X-ray structure of HIVPR.10A complex confirms that the two pyrazole rings of 10A form bidentate hydrogen bonds with the side-chain oxygen (C=O) and backbone nitrogen (N-H) of Asp30/30' of HIVPR.