 Tipranavir is a nonpeptidic HIV-1 protease inhibitor and reached the market in 2005.Unlike other HIV protease inhibitors on the market, tipranavir was developed from a nonpeptidic coumarin template and its antiprotease activity was discovered by high-throughput screening.This sulfonamide containing 5,6-dihydro-4-hydroxy-2-pyrone had emerged from screenings of 3-substituted coumarins and dihydropyrones.