Synthesis and biological activity of 3,4-dihydroquinazolines for selective T-type Ca2+ channel blockers

We have synthesized 3,4-dihydroquinazoline derivatives for the potent and selective T-type Ca2+ channel blockers and evaluated for their inhibitory activities against two subtypes T-type Ca2+ channels and N-type Ca2+ channels. Among them, 5b (KYS05044, IC50 = 0.56 ± 0.10 μM) was identified as potent T-type Ca2+ channel blocker with in vitro selectivity profile at meaningful level (T/N-type, SI = >100).