[C:1]([O:4][CH2:5][CH:6]([CH2:10][O:11][C:12](=[O:14])[CH3:13])[CH2:7][CH2:8]O)(=[O:3])[CH3:2].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(Br)(Br)(Br)[Br:35]>CN(C)C=O>[C:1]([O:4][CH2:5][CH:6]([CH2:10][O:11][C:12](=[O:14])[CH3:13])[CH2:7][CH2:8][Br:35])(=[O:3])[CH3:2]A mixture of 2-acetoxymethyl-4-hydroxy-but-1-yl acetate 10 g, 49 mmol), triphenylphosphine (19.25 g, 73 mmol) and carbon tetrabromide (24.4 g, 73 mmol) was stirred for 18 hours at 4° C. in dimethylformamide (150 ml). The solvent was then evaporated, and the residue purified by column chromatography on silica gel, eluting with ether-light petroleum 2:3 to afford 2-acetoxymethyl-4-bromobut-1-yl acetate as a pale oil (130 g, 99%). δH (CDCl3) 1.73-2.56 (3H, m, CHCH2CH2), 2.04 (6H, s, 2×OCOCH3), 3.44 (2H, t, CH2Br), 4.04 (4H, d, 2×CH2OCOCH3).
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