S(=O)(=O)(O)O.[CH3:6][C:7]1[C:8](=[O:18])[C:9]2[C:14]([C:15](=[O:17])[CH:16]=1)=[CH:13][CH:12]=[CH:11][CH:10]=2.[CH3:19]O>[Zn].C1(C)C=CC=CC=1>[CH3:19][O:17][C:15]1[C:14]2[C:9](=[CH:10][CH:11]=[CH:12][CH:13]=2)[C:8]([OH:18])=[C:7]([CH3:6])[CH:16]=14.9 g of concentrated sulfuric acid were added dropwise to a stirred mixture of 4.75 g (27.6 mmole) of 2-methyl-1,4-naphthoquinone, 2.71 g (41.4 mmole) of zinc powder, 15 mL of methanol and 15 mL of toluene, in an ice bath. After the addition was complete, the reaction mixture was stirred for 4.5 hours at 60° C. The reaction product was extracted with ethyl acetate, washed with water then brine, dried over sodium sulfate, filtered, then evaporated under reduced pressure to yield 4.25 gm (81% yield) of the title compound as an off-white powder having a melting point of 102-103° C. and an 1HNMR as follows: (300 MHz, DMSO-d6) δ 2.38 (s, 3H), 3.91 (s, 3H), 6.76 (s, 1H), 7.42(m, 2H), 8.04 (d, 1H, J=8.1 Hz), 8.14 (d, 1H, J=8.1 Hz), 8.50(bs, 1H). The mass spectrum showed a molecular ion at m/z 188.
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