The use of N-heterocyclic carbene (NHC) catalysis has emerged as an environmentally friendly method in lieu of transition metal catalysis, and displays a plethora of reaction pathways taking the field of organic synthesis forward. In combination with an oxidant, NHC catalysis can utilize readily available aldehydes as acyl donors via the acyl azolium intermediate (Scheme 1c), thus circumventing the need to generate sensitive activated acyl-donors in advance.