Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
3-Aminopropanol reacts with aryl(or aralkyl or alkyl)isothiocyanates R—N=C=S to yield the corresponding thio-ureas R—NH—CS—NH—(CH2)3OH which, refluxed with hydrochloric acid, are cyclized by elimination of water. The cyclization products are identical with the hydrothiazines resulting by elimination of sulfate or phosphate from the sulfuric or phosphoric monoesters of these thio-ureas. The resulting hydrothiazines are either 2-(R-imino)-tetrahydro-m-thiazines (I) or 2-(R-amino)-dihydro-Δ2-m-thiazines (II). Their structure has been established by comparison of their spectra with those of model compounds in one of which the C=N double bond is certainly endocyclic (2-methyl-dihydro-Δ2-m-thiazine), the other presenting an exocyclic C=N double bond (3-methyl-2-phenylimino-tetrahydro-m-thiazine). When R is an aryl group, the C=N double bond is exocyclic (structure I with 〉C=N—Ar), and one may presume that this structure is stabilized by resonance. When R is an aralkyl or an alkyl group, the C=N double bond is endocyclic (structure II). The nmr spectra were taken with three types of solvent: CDCl3 or CCl4; (CD3)2SO; CF3COOH. In CF3COOH solution the benzylic protons of the hydrothiazine with R = pF—C6H4CH2— couple with NH (J=5,5cps) which confirms the endocyclic position of the C=N double bond in this case.
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