Multicomponent Reaction of Imidazo[1,5-a]pyridine Carbenes with Aldehydes and Dimethyl Acetylenedicarboxylate or Allenoates: A Straightforward Approach to Fully Substituted Furans

The facile three-component reactions of N,N-substituted imidazo[1,5-a]pyridine carbenes, namely imidazo[1,5-a]pyridin-3-ylidenes, with aldehydes and DMAD or allenoates were disclosed. Both reactions proceeded via tandem nucleophilic addition, [3 + 2]-cycloaddition, and ring transformation to produce different 4-[(2-pyridyl)methyl]aminofuran derivatives generally in moderate yields. This work not only provided the first example of the application of imidazo[1,5-a]pyridin-3-ylidenes in organic synthesis but also developed a straightforward approach to fully substituted furans that are not easily accessible by other methods.