Monomethyl-substituted amine group

Carbamates all have the general structure of RO(CO)NHCH3. It turns out that only carbamates with a monomethyl-substituted amine group are biologically active. Although these compounds are not widely used any more, there are two carbamates, the structures of which we should be aware. 

Dimethylcarbonate (DMC) is an environmentally friendly substitute for dimethylsulfate (DMS) and methyl halides in methylation reactions. It is also a very selective reagent. The reactions of DMC with methylene-active compounds produce monomethylated derivatives with a selectivity not previously observed. The batchwise monomethylation of arylacetonitriles, arylacetoesters, aroxyacetonitriles, methyl aroxyacetates, ben larylsulfones and alkylarylsulfones with DMC achieve >99% selectivity at 180-220°C in the presence of K2CO3. Mono- -methylation of primary aromatic amines at 120-150 °C in the presence of Y- and X-type zeolites, achieved selectivities up to 97%. At high temperature (200°C) and in the presence of potassium carbonate as the catalyst, DMC splits benzylic and aliphatic ketones into two methyl esters in contrast, DMC converts ketone oximes bearing a methylene group to 3-methyl-4,5-disubstituted-4-oxazolin-2-ones. Dibenzylcarbonate... 

Schwenk and Block [23] also suggested the use of morpholine as an amine, which permits operations in ordinary laboratory equipment. The reaction appears to be quite general for aromatic monomethyl ketones. Substitutions such as nitro, amino, hydroxy, or second ace-toxy groups interfere with the standard reaction, probably because these functional groups are capable of reacting with sulfur, polysulfides, or other components of the reaction mixture. 

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