Synthesis of Tris(indol‐3‐yl)methanes From Indoles, CO2, and Dimethylphenylsilane With BPh3: Two‐Step Construction of π‐Conjugated Systems
- 1Graduate School of Environmental, Life, Natural Science and Technology Okayama University Okayama Japan
Abstract
Tris(indol‐3‐yl)methanes were synthesized from indoles, CO2, and PhMe2SiH in the presence of BPh3 in acetonitrile at 50°C. This is the first CO2 fixation reaction forming the aliphatic methine (>CH─) group. The isotope‐labeling experiments clearly demonstrated that the carbon and hydrogen atoms of the methine group originated from carbon dioxide and dimethylphenylsilane, respectively. The mechanism for the multicomponent cascade reaction was elucidated by DFT calculations. One of the CO2‐derived products, tris(4‐bromo‐1‐methylindol‐3‐yl)methane, underwent palladium‐catalyzed intramolecular cascade reactions for the selective formation of two novel polycyclic heteroaromatic compounds, where the methine C(sp 3) atom originating from CO2 was converted into aromatic C(sp 2) atoms. One is formally produced via double direct C─H arylation, Wacker‐type oxidation, dehydrogenation, and debromination, while the other seems to be produced via the intramolecular homocoupling of aryl bromide, direct C─H arylation, Wacker‐type oxidation, and dehydrogenation. Both of them are new intramolecular cascade reactions that are useful for the short‐step construction of nitrogen‐doped nanographenes. On the other hand, one of the CO2‐derived products, tris(1‐pentylindol‐3‐yl)methane, was converted into tris(1‐pentylindol‐3‐yl)methylium methanesulfonate, which is a potential antitumor drug. This is the first derivatization of CO2 to a cationic C(sp 2) center.
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BibTeX
@article{li2026synthesis,
title = {{Synthesis of Tris(indol‐3‐yl)methanes From Indoles, CO2, and Dimethylphenylsilane With BPh3: Two‐Step Construction of π‐Conjugated Systems}},
author = {Sha Li and So Saibara and Reito Yasui and Kazuto Takaishi and Natsumi Nitta and Tadashi Ema},
journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},
year = {2026},
month = jul,
doi = {10.1002/chem.71464},
url = {https://doi.org/10.1002/chem.71464},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Synthesis of Tris(indol‐3‐yl)methanes From Indoles, CO2, and Dimethylphenylsilane With BPh3: Two‐Step Construction of π‐Conjugated Systems
AU - Sha Li
AU - So Saibara
AU - Reito Yasui
AU - Kazuto Takaishi
AU - Natsumi Nitta
AU - Tadashi Ema
PY - 2026
DA - 2026/07/29
JO - Chemistry (Weinheim an Der Bergstrasse, Germany)
DO - 10.1002/chem.71464
UR - https://doi.org/10.1002/chem.71464
AB - Tris(indol‐3‐yl)methanes were synthesized from indoles, CO2, and PhMe2SiH in the presence of BPh3 in acetonitrile at 50°C. This is the first CO2 fixation reaction forming the aliphatic methine (>CH─) group. The isotope‐labeling experiments clearly demonstrated that the carbon and hydrogen atoms of the methine group originated from carbon dioxide and dimethylphenylsilane, respectively. The mechanism for the multicomponent cascade reaction was elucidated by DFT calculations. One of the CO2‐derived products, tris(4‐bromo‐1‐methylindol‐3‐yl)methane, underwent palladium‐catalyzed intramolecular cascade reactions for the selective formation of two novel polycyclic heteroaromatic compounds, where the methine C(sp 3) atom originating from CO2 was converted into aromatic C(sp 2) atoms. One is formally produced via double direct C─H arylation, Wacker‐type oxidation, dehydrogenation, and debromination, while the other seems to be produced via the intramolecular homocoupling of aryl bromide, direct C─H arylation, Wacker‐type oxidation, and dehydrogenation. Both of them are new intramolecular cascade reactions that are useful for the short‐step construction of nitrogen‐doped nanographenes. On the other hand, one of the CO2‐derived products, tris(1‐pentylindol‐3‐yl)methane, was converted into tris(1‐pentylindol‐3‐yl)methylium methanesulfonate, which is a potential antitumor drug. This is the first derivatization of CO2 to a cationic C(sp 2) center.
SN - 0947-6539
SN - 1521-3765
ER -