A method for the synthesis of 1-Alkyl-3-sulfonamido-1H-pyrroles by the Rh(ii)-catalyzed denitrogenative coupling of two different types of 1,2,3-Triazoles, 1-Alkyl-4-Aryl-and 1-sulfonyl-4-Aryl-1,2,3-Triazoles, has been developed. According to the DFT calculations, the reaction proceeds via the attack of the rhodium-bound azavinyl carbene, derived from the sulfonyl-1,2,3-Triazole, at the N2 atom of the 1-Alkyl-4-Aryl-1,2,3-Triazole and the successive formation of the rhodium-bound 1,2,3-Triazol-3-ium ylide, metal-free 1,2,3-Triazol-3-ium ylide, 1,4,5,8-Tetraazaocta-1,3,5,7-Tetraene, and 3-(azavinyl)-3,4-dihydro-1,2,4-Triazine. The concerted denitrogenative ring contraction of the latter followed by 1,2-prototropic shift affords the 1-Alkyl-3-sulfonamidopyrrole. This protocol provides 3-sulfonamidopyrroles from 1-Alkyl-4-Aryl-1,2,3-Triazoles in 24-91% yield. In contrast to 1-Alkyl-4-Aryl-1,2,3-Triazoles, 1,4-dialkyl-1,2,3-Triazoles under the same conditions afford stable 1,2,3-Triazol-3-ium ylides in 30-99% yield.
Scopus subject areas
- Organic Chemistry