4-Methylthiouracil

The synthesis of 6-methyluracil from ethyl acetoacetate and urea was described first by Behrend.i The substance has been obtained also by the action of lead hydroxide on methylthiouracil in an alkaline medium, and by boiling benzalmethylhydroxypyri-midinhydrazine with hydrochloric acid. ... 

Methyl silicate, 93 a-Methylstyrene, 93 Methyl-tert-butyl ether, 90 Methyl thiocyanate, 93 Methylthiouracil, 93 Methyltrichlorosilane, 94 Methyl vinyl ketone, 94 Methylal, 89 Metolachlor, 94 Metolcarb, 94 Metorex (Pty) Ltd., 199 Metribuzin, 94 Metronidazole, 94 Mevinphos, 94 Mexacarbate, 94... 

Although the antithyroid activity of compounds incorporating an enolizable thioamide function was discussed earlier, this activity was in fact first found in the pyrimidine series. The simplest compound to show this activity, methylthiouracil (80) (shown in both enol and keto forms), is prepared quite simply by condensation of ethyl acetoacetate with thiourea.Further work in this series shows that better activity was obtained by incorporation of a lipophilic side chain. Preparation of the required dicarbonyl compound starts with acylation of the magnesium enolate of the unsyrametrically esterified malonate, 81, with butyryl chlo-... 

QHiqO 141-97-9) see Aminophenazone Baclofen Cefotaxime Ceftazidime Chloroquine Cloricromen Cloxacillin Dipyridamole Felodipine Flutoprazepam Hymecromone Kawain Lacidipine Leflunomide Methylthiouracil Nevirapine Nitrendipine Oxacillin Pentoxifylline Propyphenazone Sulfamerazine acetoacetic acid 4-(trifluoromethyl)anilide (C H (,F3N02 351-87-1) see Leflunomide acetoacetyl chloride... 

In a hyperfunctioning of the thyroid gland, secretion of an excess quantity of thyroid hormones leads to a hyperthyroid condition (Basedow s disease, goiter). In this condition, drags are used that suppress production of thyrotropic hormones in the anterior lobe of the hypophysis (diiodotyrosine), in the thyroid gland (propylthiouracil, methylthiouracil,... 

Drugs used for hyperthyroidism can be classified as drugs that suppress thyroid hormone synthesis in the anterior lobe of the hypophysis, and they consist of diiodotyrosine and iodine, as well as drugs that suppress thyroid hormone synthesis in thyroid glands (propylthiouracil, methylthiouracil, methimazole, and carbimazole). 

The most useful drugs used for this purpose are classified as thioamides. They are chemically similar and contain thiourea-like thioamide functional groups. The most preferred are propylthiouracil and methimazole, although methylthiouracil and carbimazole are widely used. 

Methylthiouracil Methylthiouracil, 6-methyl-2-thio-2,4-(lH,3H)-pyrimidindione (25.2.3), is synthesized in a completely analogous manner by condensing ethyl acetoacetate with thiourea in the presence of sodium ethoxide [14]. 

Methylthiouracil is used for the same indications as propylthiouracil. Synonyms of this drug are murcain and thiocyl. 

Methimazole also directly disrupts thyroxine and triiodothyronin sysnthesis in the thyroid gland, and it is used for the same indications as propylthiouracil and methylthiouracil to treat hyperfunctioning thyroid glands in patients with Basedow s disease. Synonyms of this drug are merazolil, thiamazole, metothyrin, timidazol, and others. 

Antihistamine Brompheniramine, cimetidine, methapheniline, methylthiouracil, mianserin, ranitidine, thenalidine, tripelennamine... 

The most important and powerful thyreostatic drugs used hitherto are the thiouracil analogues, such as thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil and die mercaptoimidazole analogues such as tapazole or methimazole. New thyreostatics as mercaptobenzimidazole are said to have been misused recently in some EU countries. 

The most recent modification of the NBD-Cl method involves a further improvement in its qualitative support (616). It involves the infusion of the extract employed for thin-layer chromatography via an electrospray interface into a mass spectrometer operating in the multiple-stage mass spectrometry mode, thus allowing confirmation of suspect results. The cleanup of the thyroid gland samples was also performed with a selective extraction procedure, based on the specific complex formation of the thiouracil, methylthiouracil, propylthiouracil and phenylthiouracil, tapazole, and mercaptobenzimidazole residues with mercury ions bound in a Dowex 1-X2 affinity column. 

A mercurated affinity column was also employed by Schilt et al. (617) for sample cleanup in a method for the determination of residues of thiouracil, methylthiouracil, and propylthiouracil in cattle urine by gas chromatography and niuogen phosphorous or mass spectrometry detection. The presence of nitrogen... 

In the case of 4-thiouracil it is possible to compare its UV spectrum with that of l,6-dimethyl-4-methylthiouracil.516 As the spectra are different from each other, 4-thiouracil is supposed not to exist in form 58. The comparison of the UV spectrum of 4-thiouracil with those of some 5-methoxy-4-thiouracil nucleosides382 indicates that the pyrimidine residues of the latter have the same structure as that of 4-thiouracil... 

Also importantly, the same forms are found to be the most stable ones in the solid state and in solution. In contrast, isolated S2-methylthiouracil molecules under the same conditions exist in equilibrium between the 4-oxo and the 4-hydroxy tautomeric forms (30a and 30b). 

---