Abstract
Several N-(2-arylethyl)-substituted thioamides (IVa∼IVf) were synthesized from the dithioesters (V or VI) and the 2-arylethylamines in good yield, in order to test direct cyclization of the thioamides to the corresponding 3, 4-dihydroisoquinolines by a Bischler-Napieralski type reaction The comparative study of the infrared absorption spectra of the thioamides with those of the corresponding acid amides shows that the most characteristic absorption bands of the C=S group in the thioamides (IVa∼IVf) fall within four regions, namely, 1508∼1520, 1388∼1416, 1330∼1352, and 1100∼1150cm-1.
