[OH:1][C@@H:2]([CH2:6][CH:7]1[CH2:10][CH2:9][CH2:8]1)[C:3]([OH:5])=[O:4].[CH2:11](Br)[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1>CN(C=O)C>[OH:1][C@@H:2]([CH2:6][CH:7]1[CH2:10][CH2:9][CH2:8]1)[C:3]([O:5][CH2:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1)=[O:4]A mixture of 1.05 g (7.3 mmol) of 2-(S)-hydroxy-3-(cyclobutyl)propanoic acid (from Step D), 40 mL (10.0 mmol) of TEA and 1.20 mL (10.0 mmol) of benzyl bromide in 8 mL of DMF was stirred at rt for 2 h. The mixture was partitioned between 200 mL of ether and 100 mL of H2O and the layers were separated. The organic layer was washed with 100 mL of 2.0 N HCl, 100 mL of sat'd NaHCO3, 2×100 mL of H2O, 100 mL of sat'd NaCl, dried over MgSO4 and concentrated. Flash chromatography on 60 g of silica gel using 4:1 v/v hexanes/ether as the eluant afforded 1.20 g (70%) of the title compound: 1H NMR (500 MHz) δ 1.58-1.70 (m, 2H), 1.72-1.82 (m, 2H), 1.84-1.92 (m, 2H), 1.98-2.10 (m, 2H), 2.46-2.58 (m, 1H), 2.63 (br s, 1H), 4.15 (dd, J=7.5, 3.0), 7.33-7.40 (m, 5H).
Wird geladen…