[C:1]([NH:5][S:6]([CH2:9][CH:10](O)[C:11]1[CH:16]=[CH:15][N:14]=[CH:13][CH:12]=1)(=[O:8])=[O:7])([CH3:4])([CH3:3])[CH3:2].C(OC(=O)C)(=O)C.N12CCCN=C1CCCCC2>N1C=CC=CC=1>[C:1]([NH:5][S:6](/[CH:9]=[CH:10]/[C:11]1[CH:12]=[CH:13][N:14]=[CH:15][CH:16]=1)(=[O:8])=[O:7])([CH3:4])([CH3:2])[CH3:3]A mixture of N-tert-butyl-2-hydroxy-2-(4-pyridyl)ethanesulfonamide (6.62 g), acetic anhydride (13.2 ml) and pyridine (26.4 ml) was stirred at room temperature for 1.5 hr. To the reaction mixture was added 1,8-diazabicyclo[5.4.0]undec-7-ene (9.58 ml), and the mixture was stirred in an oil bath at 100° C. for 40 min. The reaction mixture was concentrated to dryness under reduced pressure. The residue was dissolved in ethyl acetate and washed with saturated brine. Th aqueous layer was extracted with ethyl acetate and organic layers were combined, dried over magnesium sulfate and concentrated to dryness under reduced pressure. The residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=1:1) to give (E)-N-tert-butyl-2-(4-pyridyl)ethenesulfonamide (3.91 g) as a pale-yellow solid.
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