Cl.[NH2:2][OH:3].[C:4](Cl)([O:6][CH2:7][CH:8]1[C:20]2[C:15](=[CH:16][CH:17]=[CH:18][CH:19]=2)[C:14]2[C:9]1=[CH:10][CH:11]=[CH:12][CH:13]=2)=[O:5]>C(Cl)Cl.O>[OH:3][NH:2][C:4](=[O:5])[O:6][CH2:7][CH:8]1[C:20]2[CH:19]=[CH:18][CH:17]=[CH:16][C:15]=2[C:14]2[C:9]1=[CH:10][CH:11]=[CH:12][CH:13]=2hydroxylamine hydrochloride (6.0 g, 86 mmol) in CH2Cl2 (250 mL) and water (100 mL) at 0° C. After 10 mins, solid FmocCl (21 g, 81 mmol) is added portionwise with vigorous stirring. After 1 h a white precipitate forms and more CH2Cl2 (100 mL) is added. The solution is allowed to warm to 20° C. and left to stir for 3 d. The white solid that remains is filtered away, re-dissolved in ethyl acetate (300 mL), washed with brine and dried over MgSO4 to yield (9H-fluoren-9-yl)methyl hydroxycarbamate (Mellor, S. L.; McGuire, C.; Chan, W. C.; Tet. Lett., 1997, 38, 3311-3314) as a white solid (15 g, 68%). Furthermore, the mother-liquor is concentrated and purified by column chromatography (silica gel, ethyl acetate/CH2Cl2 1:1 to 1:0) to yield the title compound (by-product) as a white solid (0.55 g, 1%).
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