Ambient Schmittel cyclization promoted by chemoselective triazole-gold catalyst.

The Schmittel cyclization was achieved at room temperature through triazole-gold (TA-Au) catalyzed propargyl vinyl ether rearrangement. Other tested L-Au catalysts gave complex reaction mixtures under identical conditions with no desired products observed. Importantly, because of the employment of mild conditions, sterically hindered groups (such as t-Bu) on allene termini were no longer required, which allowed successful synthesis of previously challenging substrates.