Iridium-Catalyzed Isomerization/Cycloisomerization/Aromatization of N-Allyl-N-sulfonyl-o-(λ¹-silylethynyl)aniline Derivatives to Give Substituted Indole Derivatives

Abstract

We have developed a one-iridium-catalyst system that transforms Nallyl-N-sulfonyl-2-(silylalkynyl)aniline derivatives, which are 1,7-enynes in which both multiple bonds have a heteroatom, to the corresponding substituted indole derivatives via isomerization/cycloisomerization/aromatization. This strategy provides an atom-economical and straightforward synthetic approach to a series of valuable indoles having vinyl and silylmethyl groups at the 2-and 3-positions.

Cobalt-catalysed CH-alkylation of indoles with alcohols by borrowing hydrogen methodology

“…Based on the importance of indoles and their derived compounds, the synthesis and functionalization of these heterocyclic compounds continues to be important for academic research and the pharmaceutical industry. [7][8][9][10][11][12][13][14] Among the many known indole derivatives, C3-substituted alkyl-indoles are particularly interesting because of their bioactivity (Fig. 1).…”

“…Based on the importance of indoles and their derived compounds, the synthesis and functionalization of these heterocyclic compounds continues to be important for academic research and the pharmaceutical industry. 7–14…”

Lewis Base-Catalyzed Intramolecular Vinylogous Aldol Reaction and Chemoselective Syntheses of 3-Hydroxy-2,3-Disubstituted Dihydrobenzofurans and Indolines

“…We envisioned that the dehydration of compounds 3 and 5 could afford the versatile 2,3-disubstituted 2-alkenyl benzofurans and indoles, , which are privileged core scaffolds for various bioactive natural products and pharmaceutically compounds . Known methods for constructing these motifs mainly include intramolecular aldol condensations , and transition metal-catalyzed annulation or C–H functionalization. , In the presence of the acid TsOH (20 mol %), selected 3 in toluene was heated at 60 °C for 2 h to readily afford 2,3-disubstituted 2-alkenyl benzofurans 4 via a dehydration/isomerization process (Scheme a). Compounds 3e , 3ad , and 3w all smoothly afforded the corresponding products 4 in 88–95% yields with excellent E / Z ratios.…”

Recent Advances in the Cascade Cyclization Reactions of 1,7‐Enynes

“…In 2021, Arisawa and co‐workers reported the first example of single‐iridium‐catalyzed transformation for the strategically efficient assembly of substituted indole derivatives in good to excellent yields with broad functional group compatibility (Scheme 64). [80] The reaction proceeded through a sequential isomerization/cycloisomerization/aromatization process, which allowed direct access to indoles with vinyl and silylmethyl groups at the C2‐ and C3‐positions. To illustrate the synthetic utility of the method, a scaled‐up reaction of 215 a was carried out under standard conditions, the desired product 216 a was achieved in 81% yield.…”