Selective Propargylation of Azo Compounds with Barium Reagents

摘要

A Barbier-type propargylation of azo compounds with γ-trialkylsilylated propargylic bromides has been achieved using re-active barium as a low-valent metal in THF. Corresponding propar-gylated hydrazines (α-adducts) were exclusively formed not onlyfrom azobenzenes (diaryldiazenes) but also from dialkyl azodicar-boxylates. This method is also applicable to γ-alkylated or γ-pheny-lated propargylic bromides, providing the desired propargylatedproducts only.