Manufacture of lactones

A process for the manufacture of a lactone of the general formula

• wherein each R5 independently signifies hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, optionally aromatically substituted arylalkyl, optionally aromatically substituted arylalkenyl, cycloalkylalkyl substituted or unsubstituted on the cycloalkyl moiety, heterocyclyl, substituted or unsubstituted alkanoyl, substituted or unsubstituted aroyl, substituted or unsubstituted alkylsulphonyl, substituted or unsubstituted arylsulphonyl or a silyl group Si(alkyl)3, Si(aryl)3 or Si(alkyl)1 or 2(aryl)2 or 1, and
• wherein the process comprises hydrogenating a cyclic dicarboxylic acid anhydride of the general formula:
• wherein each R5 has the significances given above, in the presence of a group VIII metal catalyst, and wherein the catalyst is chiral and wherein the metal or the metal constituent of the metal complex catalyst is used in an amount, relative to the amount of cyclic dicarboxylic acid anhydride starting material, in the range from about 0.0001 to about 10 mol %.