Functionalization of Indoles with 1,3,5-Triazinanes: Chemistry of Aminomethylation vs the Hofmann-Martius-Type Rearrangement.

We have developed efficacious routes toward the selective synthesis of two classes of compounds such as C-3 amino-methylated indoles and 4-indol-3-yl-methylanilines from the same precursors, namely, indoles and 1,3,5-triazinanes. It is reported that the controlled cleavage of 1,3,5-triazinanes can be effected by heat for the generation of aryl imine motifs, and we observed that the presence of Lewis acid influences the course of these transformations toward different products. The reaction toward indol-3-yl-methylanilines proceeds via a nucleophilic attack of indole to the aryl imine generated from the 1,3,5-triazinanes to form an amino-methylated product which undergoes a Lewis acid mediated Hofmann-Martius-type rearrangement.

Unprecedented access to functionalized pyrrolo[2,1-]isoquinolines from the domino reaction of isoquinolinium ylides and electrophilic benzannulated heterocycles.

We have come across an unexpected reaction between electrophilic indoles and isoquinolinium methylides for accessing functionalized pyrrolo[2,1-a]isoquinolines. The reaction was found in general to yield the products in good yields. We also observed the formation of S-S-bridged bis-pyrrolo[2,1-a]isoquinolines from the reaction of 3-nitro benzothiophene and isoquinolinium methylides.