Annulation of Conjugated Azine-Imine with a Sulfoxonium Ylide in a Noncarbenoid Route to Synthesize Multisubstituted Imidazole-Fused Heterocycles

A new [4+1]-annulation of in situ generated heterocyclic azine-aldimines with beta-keto sulfoxonium ylides has been developed. The reaction constructs N-fused imidazole rings. In the reaction, the ylides play a dual-functional role of a nucleophilic 1,1-dipolar one-carbon synthon and a source of an internal oxidant, dimethyl sulfoxide, that promotes in situ dehydrogenation to product scaffolds. The method enables access to imidazo-pyridine, pyrazine, and pyrimidine heteroaromatics.

Automated summary

The newly developed reaction method involves the [4+1]-annulation of in situ generated heterocyclic azine-aldimines with beta-keto sulfoxonium ylides, resulting in the construction of N-fused imidazole rings. The ylides act as a nucleophilic 1,1-dipolar one-carbon synthon and a source of an internal oxidant, dimethyl sulfoxide, promoting in situ dehydrogenation to product scaffolds. This approach enables the synthesis of imidazo-pyridine, pyrazine, and pyrimidine heteroaromatics.