GB671294A - Process for obtaining amino diols - Google Patents

Abstract

Aminodiols of the general formula <FORM:0671294/IV (b)/1> (wherein R1 and R2 are the same or different and represent hydrogen or alkyl or alkoxy radicals of not more than 4 carbon atoms) are manufactured by reducing b -substituted a -amino-b -hydroxypropionic acid esters of the general formula <FORM:0671294/IV (b)/2> (wherein R represents an alkyl radical of not more than 4 carbon atoms or an aralkyl radical). The reduction may be effected with hydrogen under a pressure of 1000-8000 (preferably 2000-4000) lbs./sq. inch in the presence of a nickel hydrogenation catalyst (preferably Raney nickel) at 20-125 DEG C. (preferably at 40-60 DEG C.) in an inert organic solvent (e.g. a lower aliphatic alcohol or an ether thereof or a cyclic aliphatic ether), or with lithium aluminium hydride in a substantially anhydrous non-hydroxylic organic solvent (e.g. ether, benzene, dioxane, toluene, carbon tetrachloride or tetra-hydrofurane), or with an alkali metal and a lower aliphatic alcohol (e.g. sodium and ethanol). Examples illustrate the application of the first of these methods to the reduction of (1) dl- or l-q -ethyl a -amino-b -hydroxy-b -phenylpropionate to dl- or l-q -1-phenyl-2-aminopropane-1 : 3-diol (the former of which is converted by warming with acetic anhydride to its O3 : N-diacetyl derivative and this compound by partial hydrolysis to dl-q -1-phenyl-2 - acetamidopropane - 1 : 3 - diol); (2) dl-reg. - methyl a - amino - b - hydroxy - b - phenylpropionate to dl - reg. - 1 - phenyl - 2-aminopropane - 1 : 3 - diol; (3) ethyl a - amino-b - hydroxy - b - (o - tolyl) - propionate to 1 - (o - tolyl) - 2 - aminopropane - 1 : 3 - diol; (4)dl - q - methyl a - amino - b - hydroxy - b -(m - methoxyphenyl)-propionate to dl-q -1-(m - methoxyphenyl) - 2 - aminopropane - 1 : 3-diol; (5) dl-q -phenethyl a -amino-b -hydroxy-b - (3 : 4 - dimethylphenyl) - propionate to dl - q - 1 - (31 : 41 - dimethylphenyl) - 2 - aminopropane - 1 : 3 - diol; (6) methyl a -amino-b -hydroxy - b - (2 - methyl - 4 1 ethoxyphenyl)-propionate to 1-(21-methyl-41-ethoxyphenyl)-2 - aminopropane - 1 : 3 - diol. In example (7) dl - q - ethyl a - amino - b - hydroxy - b -phenylpropionate is reduced with lithium aluminium hydride in anhydrous ether. b - Substituted a -amino-b -hydroxypropionic acid esters of the second general formula above are obtainable by condensing benzaldehyde or an appropriately substituted benzaldehyde with aminoacetic acid and esterifying the resulting acid with a lower aliphatic or araliphatic alcohol.