1,2-Dibromoethane → HCID 46178908, compound

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium (2.5 M in hexanes, 106 mL, 265 mmol) was added dropwise to a solution of diisopropylamine (37 mL, 264 mmol) in THF (0.8 L) over a period of 30 minutes, at −78° C., and under argon. The mixture was stirred for an additional 20 minutes at −78° C., and compound 15 (39 g, 226 mmol) was added. The mixture was allowed to warm to −20° C. for 30 minutes before 1,2-dibromoethane (47 mL, 545 mmol) was added to the mixture in one portion. After addition of the 1,2-dibromoethane, the reaction mixture was allowed to warm to 0° C. for 1.5 hours, and was then poured into a mixture of tert-butyl methyl ether (2 L) and ice cold aqueous NaHSO4 (1 M, 400 mL). The organic layer was separated, washed with a solution of aqueous NaHSO4 (1 M, 100 mL) and water (300 mL), and then washed multiple times with saturated aqueous NaHCO3 until the pH of the aqueous layer was 8 to 9. The organic layer was then washed with brine, dried over sodium sulfate, and concentrated to dryness to give crude 1vii. The crude product was distilled under high vacuum (1 mm Hg) and a fraction was collected at approximately 88° C. to 105° C. The product (13.5 g) was further purified by flash chromatography (silica gel) using dichloromethane/hexane 1:1 as the eluent. Appropriate fractions were combined and concentrated to afford pure compound 1vii as a clear oil (8.2 g, 13% yield). 1H NMR (CDCl3, δ): 0.88 (t), 1.29 (m), 1.45 (m), 1.45 (s), 1.59 (m), 1.91 (m,), 2.15 (m), 2.45 (m), 3.35 (m) and 3.40 (m) ppm; 13C NMR (CDCl3, 6): 13.9, 22.5, 28.1, 29.2, 31.1, 31.8, 35.2, 44.9, 80.5 and 174.5 ppm; MS (TOF) ESI+: [M+Na]+, 301.12, 303.12 Da.

Provenance & Evidence