[Mg].C(Br)C.[CH3:5][C:6]1[CH2:7][CH:8]2[CH:12]([CH2:13][CH:14]=1)[C:11](=O)[O:10][C:9]2=[O:16].S(=O)(=O)(O)O>C1(C)C=CC=CC=1.C1COCC1>[CH3:5][C:6]1[CH2:7][CH:8]2[CH:12]([CH2:11][O:10][C:9]2=[O:16])[CH2:13][CH:14]=1A 5-L round bottom reaction flask was charged with magnesium metal (Mg) (140 g) and THF (1 L) under nitrogen. Ethyl bromide (EtBr) (630 g) was fed into the reaction mixture dropwise while the temperature was maintained at 25° C. or below using a dry ice bath. After the feeding was completed, the reaction mixture was aged at room temperature for half an hour. Crude 5-methyl-3a,4,7,7a-tetrahydro-isobenzofuran-1,3-dione (1.7 L, ˜56% of the mass of the resulting mixture obtained in EXAMPLE I) was then added dropwise while the temperature was maintained at 25° C. using a dry ice bath. The reaction mixture was consequently further aged at room temperature for another hour. The reaction mixture was poured into sulfuric acid (H2SO4) (10%) containing ice. Toluene was added. The organic and aqueous layers were shaken in a separatory funnel and separated. The aqueous layer was further washed with toluene. The organic layers were combined and washed with sodium carbonate (Na2CO3) solution until basic. The resulting solution was then distilled to afford 3,3-diethyl-5 or 6-methyl-3a,4,7,7a-tetrahydro-3H-isobenzofuran-1-one (457 g).
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