Ensitrelvir

Uses

S-217622 is indicated for the treatment of COVID-19.

Synthesis

The synthesis of S-217622 is as follows:
To a solution of 18 (0.200g, 0.5mmol) in CH2Cl2 (3mL) at 0°C was added TFA/ H2O (10:1, 2mL), and the solution was stirred for 1h. After evaporating the solvent under reduced pressure, the corresponding deprotected lactam residue (0.100g, 0.53mmol) was coupled to the carboxylic acid 14a (0.136g, 0.38mmol) using the coupling agent HBTU (0.147g, 0.38mmol) in the presence of diisopropylethylamine (0.050mL, 0.38mmol) in DMF (3mL) at 0°C. After 5min stirring, the ice bath was removed, and the solution was allowed to stir for 2h under ambient conditions. The solvent was then evaporated under high vacuum, and the residue was dissolved in ethyl acetate (50mL). The organic layer was washed with 5% citric acid (20mL×2), 5% NaHCO3 (20mL×2), and brine (25mL). The solution was dried over Na2SO4, filtered, and evaporated under reduced pressure to give S-217622.