Copper-catalyzed fragmentation-rearrangement sequence of cycloketoxime esters

Copper-catalyzed fragmentation-rearrangement sequence of cycloketoxime esters is reported. This strategy provides direct access to diverse ring-opening acyloxylation nitriles avoiding the use of toxic cyanic reagents with good atom economy and well functional group tolerance. Experimental exploration showed that tetrabutylammonium bromide (TBAB) played an irreplaceable role in this transformation. Based on the primary mechanistic experiments, a plausible mechanism was also proposed.