[d4U]-butyne-[HI-236] as a non-cleavable, bifunctional NRTI/NNRTI HIV-1 reverse-transcriptase inhibitor

The synthesis of bifunctional compound 10 consisting of d4U joined at C-5 to a butynyl spacer attached to HI-236 is reported using a Sonogashira coupling as a key step. As a non-cleavable bifunctional HIV inhibitor incorporating an NRTI with an NNRTI, 10 shows good inhibitory activity (EC50 = 250 nM) against HIV (IIIB) replication in MT-2 cell culture, which is eight times greater than that of d4T and between those of the two component drugs.