反应详情

A solution of 4-[5-(4-chlorophenyl-3-hydroxymethyl-1H-pyrazol-1-yl]benzenesulfonamide from Step 4 (7.28 g, 0.02 mol), triphenylphosphine (6.29 g, 0.024 mol) and N,O-bis(phenoxycarbonyl)hydroxylamine prepared as described by A. O. Stewart and D. W. Brooks, [J. Org. Chem., 57, 5020-5023 (1992)] (6.01 g, 0.022 mol) in 250 mL of anhydrous tetrahydrofuran (THF) was cooled to 0° C. and treated with diisopropylazodicarboxylate (3.75 g, 0.024 mol) dissolved in 25 mL of THF. The solution was stirred at room temperature for 3 hours, concentrated in vacuo and the residue purified by flash chromatography on silica gel eluting with ethyl acetate/hexane (2:3) to afford 9.30 g, 75% of the protected hydroxylamine as a thick clear oil that was used directly in the next step.

1. concentrationconcentrated in vacuo
2. customthe residue purified by flash chromatography on silica gel eluting with ethyl acetate/hexane (2:3)