Lithium Hexamethyldisilazide → HCID 67488098, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of (4-tert-butyl-phenyl) acetic acid benzyl ester (Step C, 1.8 g, 6.38 mmol) in anhydrous THF (15 mL) was added LiHMDS (9.57 mL, 9.57 mmol, 1.0 M solution in toluene) at −78° C. The reaction mixture was stirred for 1.5 h at −78° C., and then 4-(1-bromo-ethyl)-benzoic acid methyl ester (1.7 g, 7.02 mmol, in THF 5.0 mL) was added dropwise, stirred for 2 h at −78° C. and then allowed to warm to rt for 1 h. After completion of the reaction quenched with saturated NH4Cl solution (20 mL) and stirred for 10 min. The reaction mixture was extracted with ethyl acetate (100 mL) and the organic layer was washed with brine, dried over Na2SO4 and concentrated under reduced pressure. The crude product was recrystallization from minimum amount of EtOAc and hexane at room temperature to afford 4-[2-benzyloxycarbonyl-2-(4-tert-butyl-phenyl)-1-methyl-ethyl]-benzoic acid methyl ester as a mixture of diastereomers (2.3 g, 80%), d/r(2:1): 1H NMR (300 MHz, CDCl3): δ 8.02 (d, J=8.4 Hz, 2H), 7.47 (d, J=8.4 Hz, 2H), 7.30-7.38 (m, 7H), 7.06 (d, J=6.9 Hz, 2H), 5.11 (dd, J=6.0, 12.9 Hz, 2H), 3.92 (s, 3H), 3.75 (d, J=7.5 Hz, 1H), 3.49-3.46 (m, 1H), 1.29 (s, 9H), 1.24 (d, J=6.9, Hz, 3H); TLC conditions: Uniplate silica gel, 250 microns; mobile phase=ethyl acetate-hexanes (1:4); Rf=0.6.

Provenance & Evidence