Flexible
heterocyclic moieties as the P2 ligands of HIV-1 protease
inhibitors may be adapted to the minimally distorted active site of
mutations easily and enhance activity against DRV-resistant HIV-1
variants. Herein, the design, synthesis, and biological evaluation
of a new series of inhibitors containing morpholine derivatives as
the P2 ligands were described, among which, carbamate inhibitor 23a and carbamido inhibitor 27a exhibited almost
4- and 2-fold superior activity with enzyme Ki of 0.092
nM and 0.21 nM, as well as antiviral IC50 values of 0.41
nM and 0.95 nM, respectively, compared to DRV. Besides, they exhibited
excellent activity with inhibition of 94% and 91%, respectively. Furthermore,
they also showed appreciable antiviral activity against DRV-resistant
HIV-1 variants.