The Chemical Development of LB71350

An efficient synthesis of the HIV-1 protease inhibitor LB71350 ( 1 ) is described. High diastereoselective epoxidation of the cis -allylic carbamate fragment of (5 S )-[ N -(benzyloxycarbonyl)-amino]- N -[2-methyl-(1 R )-[(phenyl)carbonyl]-propyl]-6-phenylhex-( Z )-enamide ( 16 ) and one-pot preparation of N -[(1-methylethoxy)carbonyl]-3-(methylsulfonyl)- l -valine ( 4 ) are the key features of the synthesis.