A thio-Staudinger reaction:: Thermolysis of a vinyl azide in the presence of t-butyl mercaptan

The thermal decomposition of E-3-azido-3-hexene-2,5-dione (1) in protic media gave rise to several novel reactions of the azide 1 including adducts derived from keteneimine 11. Reaction with t-butyl mercaptan yielded two products, keteneimine-derived mercaptan addition product 20 and a sulfenimine 6. Trapping of a vinyl nitrene intermediate or a thio-Staudinger reaction was considered as a possible mechanism for the formation of sulfenimine 6. The absence of the vinyl nitrene addition products 3 and 5 when the thermal decomposition was conducted in either methanol or t-butylamine suggests a thio-Staudinger reaction is operative.