Oxidation of aromatic substrates. Part 3. Synthesis of amino-acids by the selective action of ruthenium tetraoxide upon arylalkylamines

Abstract

The more strongly basic alkylamines are protected in dilute acid from oxidation by ruthenium tetraoxide, in contrast to aromatic amines which are degraded under the same conditions. One of the possibilities this offers for the selective oxidation of substituted alkylamines is illustrated by the degradation of arylalkylamines with cleavage of the aromatic ring. The only oxidation residue from the ring is a carboxy-group, which is incorporated with the retained amino-group in the product amino-acid. Yields are improved in the presence of electron-donating substituents which increase the rate of cleavage and so reduce the time of exposure of the product to further oxidation.