Study On N - Methylation Of DMSO

Methylation reaction is an important classof reaction in organic synthesis and biological processes.Various types of methylated products were found in nature.The synthesis of N-alkylated anilines play a key role in organic synthesis.N,N-dimethyl aniline compounds are very useful intermediates in the synthsis of dyes, pharmaceuticals, agrochemicals and fine chemicals.The first section of the thesis summarizes methyaltion reactions withdifferent methylating agents, including dimethyl sulfate, methyl iodide, dimethyl carbonate and methnol, which methylated compounds containing C, S, N under different catalytic systems.The search for green methylation methods, with green methyaltion agents, e.g. dimethyl carbonate or methnol,is also briefly described.In Chapter2, a metal free methylation of aromatic amines with DMSO as methylating agents is described.By adjusting the ratio of HCOOH and NEt3and the amnout of HCOOH, dimethylated amines could be obtained with high yield and selectivity. The reaction has a broad substrate scope, which tolerates primary, secondary, and heterocycle aromatic amines.Moreover,N-methylation of nitro compounds was achieved with the addition of cheap iron catalysts. FeCl2proved to be good catalyst for N-methylation of aromatic amines with DMSO as methylating agnet and HCOOH as reductant, furnishing various dimethylated amines with good to excellent yields.The reaction mechanism was investigated through deuterium labeling experiments. Mechanistic studies suggest that a methylene group from DMSO and a hydride from HCOOH are transferred to the product during the methylation process.This method provides a simple and convenient way to synthesis deuterium or13C labeled methyl amines.Comparing with other methylation methods, this new amine methylation protocol has a very broad substrate scope. Both amines and nitro compounds can be used as reactant. DMSO is cheap, low toxic and easily available.This reaction is eary to carry out and high yields can be obtained for various substrate.