Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → 4-(4-iodo-1H-pyrazol-1-yl)cyclohexanone

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Reaction Conditions

Reaction Steps

The mixture of 1-(1,4-dioxaspiro[4.5]dec-8-yl)-4-iodo-1H-pyrazole (20.0 g, 59.8 mmol), pyridinium p-toluenesulfonate (30.1 g, 120 mmol) in acetone (300 mL) and H2O (300 mL) was heated at 65° C. for 16 h. The reaction mixture was partitioned between EtOAc (200 mL) and H2O (100 mL), and the layers were separated. The aqueous layer was re-extracted with EtOAc (3×100 mL), and the combined organic fractions were washed with brine (1×), dried over Na2SO4, filtered and concentrated in vacuo resulting in 17.1 g (98% yield) of the title compound as a white solid. The material was used in the next step without further purification. 1H NMR (400 MHz, CDCl3): δ=7.54 (s, 1H), 7.52 (s, 1H), 4.62 (tt, J=4.0, 10.1 Hz, 1H), 2.64-2.38 (m, 6H), 2.36-2.24 (m, 2H). MS (ES+): m/z=291.00 [MH+]. HPLC: tR=3.37 min (polar—5 min, ZQ3).

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