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Abstract

Enolizable 2-oxoisothiocyanates Ia-If were prepared from hydrochlorides of amino ketones, containing a hydrogen atom in the α-position, by reaction with thiophosgene in the presence of CaCO₃. At room temperature the enol form of these compounds undergoes slow cyclization to give the isomeric 4-oxazoline-2-thiones IIb-IIf. In the presence of bases this isomerization proceeds rapidly even at room temperature. 2-Isothiocyanatocyclopentanone (Ia) does not cyclize to the corresponding oxazolinethione either on heating or action of bases. The rate of the thermally initiated isomerization of the 2-oxoisothiocyanates Ib-If was determined by IR spectroscopy.