A Practical Method for N-Methylation of Indoles Using Dimethyl Carbonate

Abstract

A new method for N-methylation of indoles using environmentally safe and less toxic methylating reagent, dimethyl carbonate (DMC), has been developed. The effect of various functional groups on the indole ring has been investigated. This method provides the desired product in high yields with high purity and is suitable for large-scale production. This process was used successfully in a 300-gal reactor train for N-methylation of 6-nitroindole.

Dimethyl carbonate as a modern green reagent and solvent

“…Methylation with DMC has been found to be a practical method to prepare N-methylated indole analogues in high yields and purity. 95 This process provides a high selectivity of N-methylation over C-methylation of activated methylene compounds. This method also provides an efficient way to one-pot synthesis of methyl N-methylindolecarboxylate (N-and O-dimethylation) from indolecarboxylic acid.…”

Palladium-Catalyzed Cross-Coupling of Five-Membered Heterocyclic Silanolates

“…Preparation of Dimethyl(2-indolyl)silanols-To evaluate the stability of the 2-indolylsilanols, it was first necessary to prepare a variety of N-protected 2-indolylsilanols, namely: the N-tert-butoxycarbonyl (Boc), 37 N-2-(trimethylsilyl)ethoxymethyl (SEM), 38 and N-methyl derivatives. 39 Second, the applicability of these reagents in cross-coupling with a broad range of aromatic halides (iodides, bromides and chlorides) would be examined. The investigation began with the preparation of N-Boc-dimethyl(2-indolyl)silanol 11.…”

Synthesis, Characterization, and Use of NbV/CeIV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

“…For this reason they find a wide application in the chemical industry as monomers for polymers [12] and in transesterification reactions for the production of carbonates such as diphenylcarbonate [13] and others. They are also used in the agrochemical [14] and pharmaceutical industry [15] for the production of chemicals or in product formulation. Moreover, because of their high oxygen content (53 wt % for dimethyl carbonate, 40.6 wt % for diethyl carbonate) and easy solubility in fuels, dialkylcarbonates have been proposed as replacement for methyl-tertbutyl ether (MTBE) as an attractive oxygen containing fuel additive able to match the requirements of the Clean Air Act.…”