Cooperative Iodide Pd(0)-Catalysed Coupling of Alkoxyallenes and N-Tosylhydrazones: A Selective Synthesis of Conjugated and Skipped Dienes.

Palladium(0)-catalysed hydro-alkylation or -alkenylation of alkoxyallenes with N-tosylhydrazones gives direct access to conjugated and skipped 1-alkoxydienes with high efficiency and excellent functional-group compatibility. The reaction is proposed to involve the in situ-formed t-butanol as proton source in the key step of the allylpalladium(II) species generation. Moreover, lithium iodide or iodobenzene are employed as an unprecedented iodide (I- ) reservoir to sustain the catalytic cycle.