Synthese von 5-Dialkylamino-1,2-oxazolen aus N,N-Dialkyl-?-amino-?,?,?,?-unges�ttigten Thioamiden
摘要:
3-Amino-2,4-pentadienthioamides, which were obtained from 6-dialkylamino-2H-thiopyrane-4(3H)iminium halides by alkali hydrolysis, react with hydroxylamine hydrochloride in a [C-C-C]+[N-O]-addition to give selectively 5-amino-3-alkenyl-1,2-oxazoles. These oxazoles have been identified by C-13 and H-1 NMR spectroscopic analysis. The configuration of these compounds was established on the basis of the coupling constants and 2D-NOESY-experiments. The position of the substituents has been determined by analysis of the fragmentation pattern.
1,2-Thiazole durch Ringtransformation von 2H-Thiopyran-2-thionen
摘要:
Aminolyses of 4-dialkylamino-2-methylthiothiopyranes halides with ammonia leads to 4-amino-2-dialkylaminothiopyranylium halides. On treatment with alkali these products are hydrolyzed to N,N-dialkyl-3-amino-2,4-hexadienthioamides, which react with peroxide under oxidative cyclization to 5-dialkylamino-1,2-thiazoles. In order to determine the structures of the unsaturated thioamides and isothiazoles C-13-NMR-spectroscopic analysis and a single crystal X-ray structure analysis of 5-dimethylamino-3-(2-methyl-1-propenyl)-1,2-thiazole (6a) at 100 K were carried out: C9H14N2S, M(r) = 182.28, monoclinic, P 2(1)/a, a = 11.622(2), b = 6.303(1), c = 13.678(2), beta = 104.49(3)-degrees, V = 970.1 (3)angstrom3, Z = 4, d(x) = 1.248 g/cm3, mu = 27.0 mm-1, R = 4.93%, R(w) = 4.84% (1672 observations, 157 parameters).