E. Cherbuliez, Br. Baehler, O. Espejo
1967
Citations
0
Influential Citations
18
Citations
Journal
Helvetica Chimica Acta
Abstract
3-Aminopropanol reacts with aryl(or aralkyl or alkyl)isothiocyanates RNCS to yield the corresponding thio-ureas RNHCSNH(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 CN double bond is certainly endocyclic (2-methyl-dihydro-Δ2-m-thiazine), the other presenting an exocyclic CN double bond (3-methyl-2-phenylimino-tetrahydro-m-thiazine). When R is an aryl group, the CN double bond is exocyclic (structure I with >CNAr), and one may presume that this structure is stabilized by resonance. When R is an aralkyl or an alkyl group, the CN 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 = pFC6H4CH2 couple with NH (J=5,5cps) which confirms the endocyclic position of the CN double bond in this case.