In practice, there are fewer reported skeletal edits of five-membered heteroaromatics relative to those reported for larger heteroaromatic rings. Most transformations of five-membered heteroaromatics rely on the reactivity of carbene and nitrene species with the weak -bonds in azole and diazole scaffolds to achieve ring expansions. According to our analysis, the virtual conversion of five-membered heteroaromatics into their expanded six-membered ring counterparts generally leads to a low percentage (18-34%) of commercially available compounds -indicative of high value transformations. However, according to the data presented in Figure , ringcontracting transformations of six-membered heteroaromatics give products with even lower percentages (11-28%) of characterized compounds. Given the general lack of ring-contracted analogues of the six-membered heterocycles in the Enamine 350/3 library, 43 there is clearly a need for new ring-contracting reactions of six-membered heteroaromatics.