Synthesis and calming activity of helicid derivatives containing the 3,4-dihydropyrimidin-2(H)-one and 3,4-dihydropyrimidine-2(H)-thione moiety

A series of novel helicid derivatives containing 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine2(1H)-thione moiety (3a-3f and 4a-4f) were synthesized starting from helicid. The structure of the new compounds were characterized by 1 H NMR, IR and HR-MS spectra. The sedative-hypnotic activities of the target compounds were evaluated using the test of spontaneous locomotor activity in mice. All of the derivatives produced moderate to high activities; in particular, compound 4a presented the most potent sedative-hypnotic effect in comparison to the other derivatives, and derivatives 3a, 3c, 3d, 3e and 3f also showed potent activities.