Oxaziridine reactions with thiourea

Intermediates in Reactions.— Attempts to prepare thiaziridines or selenaziridines by treatment of oxaziridines (133) with thiourea, potassium thiocyanate, potassium ethylxanthate, potassium selenoxanthate, and triphenylphosphine sulphide gave imines (135) instead, although... 

Experiments with cyclic thioethers (80JCS(P1)1693), thiourea, thiocyanate and ethyl xan-thate always led to destruction of oxaziridines (73AJC2159). Products of complicated consecutive reactions could be isolated but only with some difficulty, e.g. (92) from a reaction with carbon disulfide (74JOC957), and (93), obtained by trapping with butadiene a product of a reaction between an oxaziridine and a thiirane (80JOC1691). 

The treatment of simple and fused oxaziridines with sulfur-containing nucleophiles such as thiourea, potassium thiocyanate, potassium ethyl-xanthate, potassium selenocyanate, and triphenyl-phosphine sulfide resulted in the formation of the related imines, most probably—in analogy to the results of the treatment of oxiranes with the same reagents—via the corresponding thiaziridine intermediate. The proposed reaction mechanism is given in Scheme 8 <73AJC2159>. 

Three groups of workers have studied the reactivity of thiourea towards a -unsaturated ketonesThe notable lability in the reaction course was demonstrated by the simultaneous or alternative formation of different open-chain as well as cyclic products, thus clearly indicating the occurrence of nucleophilic attacks of both the sulphur and the nitrogen atoms of thiourea on both the carbonyl carbon and the 3-carbon atom of the a 3-unsaturated ketone. Other papers reporting on the nucleophilic activity of thioureas deal with reactions of the latter with oxirans, oxaziridines," acryloyl chloride," o 3-unsaturated acids," acetylenedicarboxylic acid esters, " ethyl thiocyanoacetate," and isocyanates. ... 

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