Methylthiouracil is an organosulfur compound that is used antithyroid preparation. It is a

thioamide A thioamide (rarely, thionamide, but also known as thiourylenes) is a functional group with the general structure R–CS–NR′R″, where R, R′, and R″ are organic groups. They are analogous to amides but they exhibit greater multiple bond ch ...

, closely related to propylthiouracil. Methylthiouracil is not used clinically in the United States, it has a similar mechanism of action and side effect to that of propylthiouricil. The drug acts to decrease the formation of stored thyroid hormone, as thyroglobulin in the thyroid gland. The clinical effects of the drug to treat the hyperthyroid state can have a lag period of up to two weeks, depending on the stores of thyroglobulin and other factors.

Synthesis

Methylthiouracil is prepared quite simply by condensation of

ethyl acetoacetate The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food. ...

with

thiourea Thiourea () is an organosulfur compound with the formula and the structure . It is structurally similar to urea (), except that the oxygen atom is replaced by a sulfur atom (as implied by the ''thio-'' prefix); however, the properties of urea a ...

. Further work in this series shows that better activity was obtained by incorporation of a lipophilic side chain.

References

{{Thyroid hormone receptor modulators Antithyroid drugs IARC Group 2B carcinogens Pyrimidones Thioureas Nucleobases