Synthesis of Isocyanate‐Substituted Allenes and 1,3‐Butadienes by [3,3] Sigmatropic Rearrangements

In the transformation of thiatriazole 1 to allenyl isocyanate (3), a [3,3] sigmatropic cyanate → isocyanate rearrangement (of 2) was followed for the first time by NMR spectroscopy. Not only alkyl derivatives of 3 but also compounds 4 and 5 can be synthesized by analogous reactions. In this process thiatriazoles, which are prepared from alcohols in one step, are employed.