Carbamide groups

The available agents with antithyroid activity are the thioamides propylthiouracil, carbimazole and methimazole also known as thiamazole. Their thio-carbamide group is indispensable for antithyroid activity. The mechanism of action is complex. The most important action is the prevention of hormone synthesis by an inhibition of the thyroid peroxidase-catalyzed reactions involved in iodine organification. These agents also block the coupling of the iodoty-rosines. 

Halogenated pyridazinones have been thus prepared from muco-chloric acid (35) 286,312-316 mucobromic acid, or the related chlorobromo acid. Instead of hydrazine semicarbazide can be used and the intermediate semicarbazone cyclized in hot acetic acid, loss of the carbamide group taking place simultaneously. Acid hydrazides likewise form hydrazones first, which cyclize with the aid of phosphorus oxychloride. Tosylhydrazones are reported to cyclize easily. ... 

Isocyanato-alkyl-triethoxysilanes are commercially available or their preparation is described [10,111 and good enantioselective catalysts with diphosphine ligands that contain carbamate or carbamide groups are own [12,131. The price, one has to pay, to use these linkers, is the introduction of an NH or OH handle onto the ligand. However, since this allows the immobilization to various different supports [4,71 or e.g. to render ligands water soluble [141, such a functionalization should always be taken into consideration when designing new ligands. 

Thus, except for some reservations concerning the position of the carbamide group and the sequence of the amino and hydroxyl groups in streptoli-dine (which would alter the size of the lactam ring), the essential structure of this group of antibiotic substances is given by formula (14). There is an... 

New stationary phases were synthesized by binding substituted aromatic groups to silica. Their separation capacity was determined by using various native CDs and CD dal-vatives. The mobile phase for the gradient elution consisted of a mixture of MeCN, H2O, and formic acid. CDs were detected with a refractive index detector and ELSD. The measurements indicated that the N-(4-nitrophenyl)-carbamide group-bonded silica was the most effective. ... 

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