The structures of 4- and 5-substituted Δ4-thiazolin-2-ones

Abstract

In order to establish the structures of compounds described as Δ⁴-thiazolin-2-ones ten sets of heterocycles (each comprising a 4- or 5-substituted Δ⁴-thiazolin-2-one, the N-methyl derivative, and the corresponding 2-methoxy-thiazole) have been examined by i.r., u.v., and ¹H and ¹³C n.m.r. spectrometry. The i.r. results established that in solution the parent compounds exist entirely or predominantly as the 2-oxo-forms. This conclusion is supported by the ¹H n.m.r. evidence, but the u.v. and ¹³C n.m.r. data do not give a clear distinction between the possible 2-oxo and 2-hydroxy-structures.