Microwave Assisted Quaternisation of an indole
SyntheticPage 841
DOI:
Submitted: July 10, 2018, published: July 10, 2018
Authors
Clare Lawrence (CLLawrence@uclan.ac.uk)
Mark Wainwright (M.Wainwright@ljmu.ac.uk)
Robert Smith (rbsmith@uclan.ac.uk)
William Stockburn (WStockburn@uclan.ac.uk)
A contribution from
Chemicals
2,3,3-Trimethylindolenine (Sigma Aldrich)
Iodomethane (Sigma Aldrich)
Procedure
2,3,3-Trimethylindolenine (0.48 g, 3.00 mmol), iodomethane (0.43 g, 3.00 mmol) and acetonitrile (3 mL) were added to a 35 mL CEM microwave reaction vessel and irradiated at 120oC for 10 minutes. The precipitate formed was isolated at the pump and washed with ethyl acetate (20 mL) and cold diethyl ether (10 mL) and dried in vacuo to give 1,2,3,3-tetramethyl-3H-indolium iodide (0.76 g, 84%) as a pink solid.
Author Comments
The authors found the above synthesis to not require purification. The microwave used for this synthesis was a CEM Discover. Note the huge signal around 3.33ppm in the 1H & COSY NMR is due to water within the d6-DMSO solvent.
Data
1H NMR (400 MHz, DMSO-d6) δ 7.90 – 7.84 (m, 1H), 7.83 – 7.76 (m, 1H), 7.66 – 7.57 (m, 2H), 3.94 (s, 3H), 2.74 (s, 3H), 1.51 (s, 6H). 13C NMR (101 MHz, DMSO) δ 196.50, 142.50, 142.02, 129.83, 129.31, 123.70, 115.53, 54.39, 35.01, 22.13, 14.39. LCMS m/z: 174.2 [M – I-].
Lead Reference
Angela J. Winstead, Grace Nyambura, Rachael Matthews, Deveine Toney and Stanley Oyaghire. Synthesis of Quaternary Heterocyclic Salts, Molecules 2013, 18, 14306-14319
Other References
Supplementary Information
Keywords
alkyl/alkenyl/aryl halides, alkylation, amines, heterocyclic compounds, microwave