Rearrangement Reactions, 6. New Functionalized Allenes: Synthesis Using Sigmatropic Rearrangements and Unusual Reactivity

The present article summarizes the synthesis of allenes, which bear a functional group with at least two heteroatoms, by [2,3] or [3,3] sigmatropic rearrangements of appropriate propargyl precursors. Recently, this method has been extended to prepare new types of functionalized allenes such as isocyanates, isothiocyanates, isoselenocyanates, azides, thiocarbonates, and azo compounds. The title compounds are very reactive as shown by rapid intra‐ and intermolecular consecutive reactions. This reactivity can be used to synthesize heterocycles and doubly functionalized 1,3‐butadienes.