Non-nucleoside HIV-1 reverse-transcriptase inhibitors. Part 10. Synthesis and anti-HIV activity of 5-alkyl-6-(1-naphthylmethyl)pyrimidin-4(3H)-ones with a mono- or disubstituted 2-amino function as novel 'dihydro-alkoxy-benzyl-oxopyrimidine' (DABO) analogues.

A series of structurally related 2,5-disubstituted 6-(1-naphthylmethyl)-pyrimidin-4(3H)-ones, compounds 6a-6r, were synthesized and evaluated for their in vitro anti-HIV activities in MT-4 cells. Most of the new compounds investigated showed moderate-to-good activities against wild-type HIV-1, with IC(50) values in the range 5.64-0.21 microM. Compound 6d was the most potent congener (IC(50)=0.21 microM, SI=724) in inhibiting HIV-1 replication, which is ca. 25 times more effective than the reference compound 2',3'-dideoxyinosine (DDI). Preliminary structure-activity relationship (SAR) studies revealed that both modulation of the amino function at C(2) and of the alkyl group at C(5) of the pyrimidine ring are crucial for high anti-HIV-1 activity.