Lithium Hexamethyldisilazide → HCID 57987540, compound

Participants

Reaction Steps

Lithium bis(trimethylsilyl)amide (1.0M in THF, 3.8 ml, 3.8 mmol) was added slowly to a stirred solution of the ester from Example 3, Step 2, (509 mg, 1.7 mmol) in dry THF (8 ml) under N2 such that the internal temperature <−70° C. After 30 minutes cis-1,4-dichloro-2-butene (210 μl, 2.0 mmol) was added. The reaction was maintained at this temperature for 30 minutes, then transferred to an ice bath. After 90 minutes the reaction was removed from the cooling bath and stirred at room temperature for 30 minutes, then quenched with saturated aqueous NH4Cl. The mixture was partitioned between EtOAc/H2O. The aqueous layer was extracted with EtOAc (×2). The combined extracts were washed with brine (×1), dried (Na2SO4), filtered and evaporated. The residue was purified by chromatography on silica, eluting with 8% EtOAc/isohexane to give the title compound (278 mg, 47%) as an oil, which solidified on standing. 1H NMR (400 MHz, CDCl3) δ: 2.81 (2H, d, J 15.2), 3.44 (2H, d, J 15.3), 3.70 (3H, s), 5.79 (2H, s), 7.22 (2H, d, J 4.4), 7.66 (1H, s), 7.73 (2H, d, J 8.1), 8.08 (2H, d, J 8.1), 8.63-8.67 (2H, d, J 5.1); M/Z (ES+) 348 (MH+).

Provenance & Evidence