Preparation of 2-substituted aminophenyl ketones

The process for producing a 2-monosubstitutedaminophenyl ketone of the formula:

• ##STR5## wherein R' is sec.-alkyl of 3 to 7 carbon atoms, cycloalkyl of 5 to 7 carbon atoms optionally monosubstituted by alkyl of 1 to 4 carbon atoms, optionally mono- or di-substituted benzyl or optionally monosubstituted furylmethyl,
• Ring B is optionally mono- or di-substituted or substituted by alkylenedioxy of 1 or 2 carbon atoms, and
• A is optionally mono- or di-substituted monocyclic aryl or optionally mono- or di-substituted naphthyl;
• from a corresponding 2-unsubstitutedaminophenyl ketone of the formula:
• ##STR6## wherein A and B are as above defined, and a carbonyl bearing compound of the formula:
• ##STR7## wherein either:
• (1) R.sub.1 ' and R.sub.2 ' are each alkyl of 1 to 5 carbon atoms with the proviso that R.sub.1 ' and R.sub.2 ' do not exceed a total of 6 carbon atoms;
• (2) R.sub.2 ' is hydrogen and R.sub.1 ' is optionally mono- or di-substituted phenyl or optionally mono-substituted furyl;
• and (3) R.sub.1 ' and R.sub.2 ' together form an alkylene bridge of 4 to 6 carbon atoms optionally mono-substituted by alkyl of 1 to 4 carbon atoms:
• comprising reacting at a temperature of from 0.degree. to 35.degree. C.;
• (A) said 2-unsubstitutedaminophenyl ketone, (B) a strong acid defined by having a strength of at least pH 2.0 in a 10% by weight aqueous solution, (C) a borohydride and (D) a stoichiometric amount of said carbonyl bearing compound, in a multi-component solvent comprising water and at least a 20% molar excess of said carbonyl bearing compound, the mol ratio of borohydride to the unsubstitutedaminophenyl ketone being at least 1.7:1, the mol rato of said acid to borohydride on a hydrogen ion mol equivalent basis being in excess of 1:1 and the individual solvent components and said acid each being in an actual amount and proportioned relative to each other and to said 2-unsubstitutedaminophenyl ketone such as to substantially initiate reaction within said temperature range in a substantially homogeneous solution.