Reactive intermediates from DMDO oxidation of ynamides. Trapping of a de novo chiral push-pull carbene via cyclopropanation.

The reaction profile of DMDO oxidations of ynamides is described. This work illustrates the first examples of highly diastereoselective intramolecular cyclopropanations of a push−pull carbene derived from alkyne oxidation. In addition, the ynamide oxidation provides facile access to ketoimides and reveals mechanistic insights into the chemistry of electronically biased oxirenes.