Reaction of ethers and oxonium salts with nitrogen compounds

Reaction of ethers and oxonium salts with nitrogen compounds 

Substitution of an amino for the alkoxyl group of simple aliphatic ethers has little preparative importance the ether linkage must be weakened by a carbonyl, carboxyl, or nitrile group in the -position if the reaction is to occur under not too drastic conditions. Certain /8-methoxy ketones of type (17) can be converted into / -amino ketones below 100°.1081 Cleavage of the ether group in activated enol ethers is still easier for instance, 2-(acetoxymethylene)- 

Ethyl 2-(aminomethylene)oxaloacetate 1089 18% Anhydrous alcoholic ammonia solution (26 g, 0.27 mole of NH3) is added in one portion to a stirred solution of 2-(ethoxymethylene)-oxaloacetate (61 g, 0.25 mole) in dry ether (250 ml) that is cooled in ice-salt. The mixture is shaken and set aside for 20 h in a closed vessel. The gelatinous precipitate is then filtered off and washed thoroughly with dry ether. Evaporating the combined filtrates in a vacuum affords a syrup, which soon crystallizes [45-49 g, 84-91% m.p. 68-69° (from ether-light petroleum)]. 

It is not always necessary to start from the pre-formed alkoxymethylene compound (2, 3, 4, etc.) they can be prepared from an orthformic ester and a compound containing a reactive methylene group and treated with the amine in one operation.1088 

Most aromatic amines1084-1088 1090,1091 and amides,1082 1090 1092 e.g., ureas, give good yields only at 100-150°. 

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