HALOGENATED UNSATURATED ALKYL COMPOUND AND ITS PRECURSOR

PURPOSE:To obtain the subject compound in which carboxyl group of eicosapentaenoic acid (EPA), etc., can be substituted with an isotope of carbon by adding methyl-lithium, etc., to a specific alpha-hydroxycarboxylic acid ester, synthesizing a diol, oxidizing the resultant diol, reducing the oxidation product and halogenating the resultant compound. CONSTITUTION:An alpha-hydroxycarboxylic acid ester compound expressed by formula I[R is methyl or butyl; when R is methyl, (m) and (n) are as follows; (m) is 6 and (n) is 2 or (m) is 5 and (n) is 3; when R is butyl, (m) is 4 and (n) is 3; R is 1-5C alkyl or aryl-substituted alkyl] is allowed to react with methyl-lithium, etc., to provide a diol compound expressed by formula II (R is 1-5C alkyl, etc.), which is then subjected to oxidative cleavage reaction and subsequently reduced to afford a compound expressed by formula III. The prepared compound expressed by formula III is then halogenated to provide the objective compound expressed by formula IV (X is chlorine or bromine). Furthermore, the above-mentioned compound expressed by formula V is made to react with gaseous carbon dioxide composed of C which is an isotope of carbon, etc., to provide a compound useful for diagnosis, etc., of diseases such as lipid dysbolism.