1,165,143. Optically active compounds. SCHERING A.G. 2 Sept., 1966 [14 Sept., 1965], No. 39325/66. Heading C2C. The invention comprises an optically active antipode of a compound of the general formula in which Ca represents an asymmetric carbon atom, Q represents a -CH 2 - or -CH 2 -CH 2 - group, V represents a keto group, V&lt;SP&gt;1&lt;/SP&gt; represents a group of the formula in which each hydroxyl group may be esterified, X represents a hydrogen atom or a methyl or ethyl group and Y represents a group of the formula which may be further substituted and in which the carbonyl group may each be present in a functionally converted form, or a group of the formula which may be further substituted and in which W represents a hydrogen atom or an alkyl group containing 1-6 carbon atoms and a process for the manufacture of an optically active antipode of the general formula in which Ca represents an asymmetric carbon atom, X represents an organic group, a halogen atom, a free hydroxyl group, a free or functionally converted amino group or (when Z&lt;SP&gt;1&lt;/SP&gt; does not represent a hydrogen atom) a hydrogen atom, Y represents an organic group which, if X represents an organic group, is different from that group, and Z represents a -COOH group and Z&lt;SP&gt;1&lt;/SP&gt; represents a H atom or the two Z&#39;s in the starting material are identical and Z and Z&lt;SP&gt;1&lt;/SP&gt; represent different organic groups each being different from the organic group represented by Y and from the organic group, if present, represented by X, the organic group represented by Z&lt;SP&gt;1&lt;/SP&gt; being a group that is obtainable in an organic compound from the organic group represented by Z by treatment (under conditions suitable for fermentation) with a micro-organism or an enzyme of such a micro-organism, or the two Z&#39;s in the starting material together with the C carbon atom represent an organic cyclic group&#39; being different from the organic group, if present, represented by X and Y together with the C i  carbon atom, being symmetrical with respect to the C i  carbon atom, and Z and Z&lt;SP&gt;1&lt;/SP&gt; in the product together with the C a  carbon atom represent an organic cyclic group being different from the organic cyclic group, if present, represented by X and Y together with the C a  carbon atom and comprising a first group and a second group which first and second groups are present in positions that are symmetrical with respect to the C a  carbon atom, the first group being one of the aforesaid two identical groups and the second group being a group that is obtainable from the first group by treatment (under conditions suitable for fermentation) with a micro-organism or with an enzyme of such a micro-organism, wherein a compound of the formula in which X, Y and Z are as defined above, and C 1  represents an optically inactive carbon atom is treated under conditions suitable for fermentation with a micro-organism or with an enzyme of such a micro-organism. As starting materials there may be used the dimethyl and diethyl esters of #-(3,4-methylenedioxyphenyl)-glutaric acid, 3-(3,4-methylenedioxyphenyl) - pentane - 1,5 - dione, 2 - (3,4 - methylenedioxybenzyl) - propane - 1,3 - dione, 1 - methyl - 1 - (6 - carboxy - 3 - ketohexyl) - cyclopentane - 2,5 - dione, piperonyl - malonic acid diethyl ester, and 2-(3,4-methylenedioxybenzyl) - propane - 1,3 - diol diacetate. Suitable micro-organisms are the fungus Aspergillus ochraceus, Aspergillus niger, Curvularia lunata, Rhizopus nigricans or Penicillium notatum; the yeasts Saccharomyces uvarum, S. cerevisiae, S. carlsbergensis, S. pastorianus or S. ellipsoides, the bacteria Bacillus esterificans, B. laterosporus, Brevibacterium vitarumen, Propionibacterium arabinosum, Protaminobacter alboflavus, Mesentericus spec., Mycoplana dimorpha or Bacillusthuringiensis.