Au(I)‐Catalyzed Annulation of Benzofurazan N‐oxides with Ynamides: From Predicting the Chemo‐Selectivity to the Synthesis of 7‐Nitroindole Derivatives

Summary of main observation and conclusion It could be proposed that gold(I)-catalyzed reactions of ynamides with benzofurazan N-oxides might proceed through either O-attack or N-attack to afford alpha-oxo or alpha-imino Au(I)-carbenoid intermediates. Computational studies were performed to predict that benzofurazan N-oxides are ready to undergo the chemoselective N-attack to the Au(I)-activated ynamides to generate the alpha-imino Au(I)-carbenoid intermediate. Experimental studies were carried out to confirm the computational results and the 7-nitroindole derivatives were synthesized in a concise and efficient manner. The unfavored O-attack for benzofurazan N-oxides, which is in contrast to nitrones and pyridine/quinoline N-oxides, in the Au(I)-catalyzed reactions with ynamides is rationalized.