Thiourea was used with similar success to provide the
corresponding 3,4-dihydropyrimidin-2(1H)-thiones
which are also of interest with regard to their biological
activities. For example monastrol 4y, a mitotic kinesin
Eg5 motor protein inhibitor and a potential new lead
for the development of anticancer drugs, was obtained
in a 92% yield (Table 2, entry 25).19