1,5-Dibromopentane → Ethyl 7-bromo-2-methyl-2-phenylheptanoate

Participants

Reaction Steps

Under N2 atmosphere, a solution of LDA (2.0 M in heptane/THF/ethylbenzene, 1.85 mL, 3.70 mol) was added dropwise to a stirred solution of 202 (660 g, 3.70 mol) in anhydrous THF (6.6 L) over 30 min at −78° C. After 1 h, 1,5-dibromopentane (1390 g, 6.05 mol) was added, followed by the addition of DMPU (660 mL). The reaction mixture was stirred for 1 h, then warmed to room temperature and stirred overnight. The mixture was poured into saturated aqueous NH4Cl solution (24 L) and extracted with ethyl acetate (4×6.7 L). The combined organic layers were washed with brine (9 L), 1 N HCl (6 L), saturated aqueous NaHCO3 solution (6 L), and brine (6 L). The solution was dried over MgSO4 and concentrated in vacuo. The residue was distilled in high vacuo to yield 205h (700g, 58%) as a yellowish oil. Bp 140-145° C./0.3 mmHg. 1H NMR (CDCl3): δ 7.30-7.20 (m, 5 H), 4.09 (m, 2 H), 3.34 (t, 2 H, J=6.9), 2.05-1.80 (m, 4 H), 1.53 (s, 3 H), 1.43-1.14 (m, 4 H), 1.16 (t, 3 H, J=6.6). 13C NMR (CDCl3): δ 176.03, 143.99, 128.33, 126.60, 125.89, 60.68, 50.11, 39.03, 33.75, 32.51, 28.59, 23.93, 22.78, 14.10. HRMS (LSIMS, nba): Calcd for C16H24BrO2 (MH+): 327.0960, found: 327.0952. HPLC: 91.2% pure.

Provenance & Evidence