Silver‐Catalyzed [2+1] Cyclopropenation of Alkynes with Unstable Diazoalkanes: N‐Nosylhydrazones as Room‐Temperature Decomposable Diazo Surrogates

The [2+1] cycloaddition of alkynes with diazo compounds represents one of the most powerful and reliable methods for the construction of cyclopropenes. However, it remains a formidable challenge to accomplish the cyclopropenation of alkynes with non‐stabilized diazoalkanes, owing to the fact that such compounds are unstable and prone to detonation. Herein, we report a general silver‐catalyzed cyclopropenation reaction of alkynes with unstable diazoalkanes, by for the first time the discovery and application of N‐nosylhydrazones as room‐temperature decomposiable diazo surrogates. This method allows for the efficient assembly a wide variety of cyclopropene derivatives that are otherwise difficult to access by conventional methods. Three′s the charm: A silver‐catalyzed general [2+1] cyclopropenation reaction of alkynes with unstable diazoalkanes has been developed, having discovered the potential of N‐nosylhydrazones as room‐temperature decomposiable diazo surrogates. This report displays a powerful synthetic method toward a variety of cyclopropene derivatives that are otherwise difficult to access by conventional methods.