Abstract: A process for producing an optically active form of a compound of formula (I) ##STR1## wherein R.sub.1 represents hydrogen or a hydrocarbon group that may be substituted; R.sub.2 and R.sub.3 independently represent hydrogen, a hydrocarbon group that may be substituted, or a heteroaromatic group that may be substituted; X' represents a substituent comprising an esterified carboxyl group or an acylated hydroxyl group; ring A represents a benzene ring that may be substituted or a heteroaromatic ring that may be substituted; ring J' represents a 7- or 8-membered heterocyclic ring containing at most 3 hetero-atoms as ring-constituent members, which may have a further substituent or substituents in addition to R.sub.1, R.sub.2, R.sub.