p-Toluenesulfonic acid monohydrate → 2-methyl-7-(2,4,6-trimethyl-phenyl)-3-vinyl-2H-indazole

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A solution of 1-[2-methyl-7-(2,4,6-trimethyl-phenyl)-2H-indazol-3-yl]-ethanol (0.263 g, 0.893 mmol) and 4-toluenesulfonic acid hydrate (0.217 g, 1.14 mmol) in 10 mL of toluene was stirred at 103° C. for 16 h then allowed to cool. The yellow-orange solution was sequentially washed with 10 mL of a 10% aqueous NaOH solution and 10 mL of a saturated aqueous NaCl solution, dried over MgSO4, filtered, and concentrated to an orange oil. Column chromatography (20% EtOAc/hexanes) afforded 2-methyl-7-(2,4,6-trimethyl-phenyl)-3-vinyl-2H-indazole (15: Ra=Rb=H, Ar=2,4,6-trimethylphenyl; 0.135 g; 55%; m.p. 84.9-95.4) as a pale yellow solid.

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