TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The compound (III) is prepared by: (3) cycloaddition of ketene of formula H-CH=C=O (IV) and acetone in the presence of a solvent (3) and an acid (3), to obtain a 4,4-dimethyl-oxetan-2-one (V); and (4) ring opening of the compound (V) in the presence of a solvent (4) and a salt (4). The step 1), step 2) and step 4) are performed in one pot. The reaction temperature of step (2) is -5 degrees C to 55 degrees C. The compound (III) is prepared by: (3b) cycloaddition of the ketene (IV) and acetone in the presence of a solvent (3b) and an acid (3b) to obtain a 2,2,6,6-tetramethyl-(1,3)dioxan-4-one (VI); and (4b) ring opening of the compound (VI) in the presence of a solvent (4b) and a salt (4b). The, step 1), step 2) and step 4b) are performed in one pot. In step 1) and step 2) no chloroform and no bromoform and no iodoform is present. The protonation of step (1) is done at a pH of 3.5-6.2 or 3.6 to 6.1. The method involves: (4) ring opening of the compound (V) or (VI) in the presence of a solvent (4) and a salt (4), where the solvent (4) is water and the salt (4) is NaOH, to obtain the compound (III); and (5) preparation of the compound (I) by metal exchange of the compound (III) in the presence of a water and a salt (5), where the salt (5) is CaCl2, CaBr2, CaO, and Ca(OH)2. Preferred Components: The solvent (3) is selected from acetone, pentane, hexane, heptane, dichloromethane, dichloroethane, carbon tetrachloride, toluene, xylene, or mesitylene. The acid (3) is a Lewis acid selected from montmorillonite, BF3.Et2O, BF3.Me2O, B(OH)3, BF3.THF, BF3.Me2S, BCl3, AlCl3, AlBr3, FeCl3, ZnCl2, SnCl4, Ce(OTf)3, TiCl4, GaCl3, or LiCl. The solvent (4) is selected from water, acetonitrile, hexanes, heptanes, dichloromethane, dichloroethane, carbon tetrachloride, toluene, xylene, mesitylene, dioxane, 1-4C alkyl ether, THF, or 2-methyltetrahydrofuran. The salt (4) is selected from Mg(OH)2, Ni(OH)2, Cu(OH)2, Ag(OH), Li(OH), K(OH), or Na(OH). The salt (2) in step 2) is selected from Ca(OH)2, CaO and CaCl2. The solvent (4) in step 4) is water. The solvent (4) in step 4) is a mixture of water and methyl tert-butyl ether (MTBE). The solvent (1) in step 1) is the same as the solvent (4) in step 4). The acid (1) in step 1) is aqueous HCl or H2SO4. The salt (4) in step 4) is NaOH. The solvent (2) in step 2) is selected from water, ethanol, 2-methyl-1-propanol, isopropanol, acetone, and methanol. The solvent (2) in step 2) is ethanol. The solvent (2) in step (2) is a mixture of ethanol and water. The mixture of ethanol and water in an ethanol:water w/w ratio of 99:1 to 90:10. The solvent (2) is a mixture of water and acetone. The solvent (2) is a mixture of water and isopropanol. The solvent (2) is water. The solvent (3b) is selected from acetone, pentane, hexane, heptane, dichloromethane, dichloroethane, carbon tetrachloride, toluene, xylene, and mesitylene. The acid (3b) is a Lewis acid selected from montmorillonite, BF3.Et2O, BF3.Me2O, B(OH)3, BF3.THF, BF3.Me2S, BCl3, AlCl3, AlBr3, FeCl3, ZnCl2, SnCl4, Ce(OTf)3, TiCl4, GaCl3, and LiCl. The solvent (4b) is selected from water, acetonitrile, hexane, heptane, dichloromethane, dichloroethane, carbon tetrachloride, toluene, xylene, mesitylene, dioxane, 1-4C alkyl ether, THF, and 2-methyltetrahydrofuran. The salt (4b) is selected from Mg(OH)2, Ni(OH)2, Ag(OH), Li(OH), K(OH), and Na(OH). The solvent (4b) in step 4b) is water. The solvent (4b) in step 4b) is a mixture of water and MTBE. The solvent (1) in step 1) is the same as the solvent (4b) in step 4b), where the salt (4b) in step 4b) is NaOH. The salt (5) is CaCl2. The compound (I) is a monohydrate. Preferred Definitions:    n=1;    m=1 or 2;    N=Na.    ACTIVITY - Antilipemic. No biological data given.    MECHANISM OF ACTION - None given.    EXAMPLE - Aqueous sodium hydroxide (NaOH) (45.5 g) was added to methyl tert-butyl ether (MTBE) (75 ml). The reaction mixture was cooled to 5 degrees C, then 4,4-dimethyloxetan-2-one (25 g) in MTBE (50 ml) was added dropwise at 5 degrees C. After complete addition (20 minutes), the reaction mixture was allowed to warm to room temperature within 20 minutes and stirring was continued for further 1.5 hours. The biphasic solution was cooled to 0 degrees C and aqueous HCl (38.5 g) was added dropwise until a pH of 4 was reached. After work up, calcium 3-hydroxy-3-methylbutyrate (26 g, yield 75%, purity 99.5%) was obtained.