✍ Scribed by S�mengen, Dogan; Pelter, Andrew
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Disubstituted A2-1 ,2,4-oxadiazoline-5-thiones are prepared by the reaction of N-substituted amidoximes with thiophosgene. Rearrangement, catalysed by either light or metallic copper, yields the corresponding 3,4-disu bstituted A2-I ,2,4-thiadiazolin-5-ones.
Preparative Studies.-We have previously shown that Nsubstituted amidoximes (1) react with ethyl chloroformate t o give 3,4-disubstituted A'-1,2,4-0xadiazolin-5-ones (2) (Scheme 1). We expected that the corresponding 5-thiones (3), which we wished to study, would be available by conversion from (2) using phosphorus pentasulphide, a reaction for which there are a n a l o g i e ~. ~* ~ When (2a) [see Scheme for key to substituents on compounds (2), (3), and (4)] is refluxed in o-xylene with an excess of phosphorus pentasulphide for 3 h, it is mainly unchanged,
📜 SIMILAR VOLUMES
The fragmentation behaviour of 3,4-disubstituted 1,2,4-oxadiazole-5(4H)-thiones under electron impact (EI) can be explained by postulating a predominant rearrangement to the corresponding 3,4-disubstituted 1,2,4-thiadiazole-5(4H)-ones before further fragmentation. This postulate is confirmed by a co