反应详情

A 1M solution of potassium tert-butoxide in THF (80 mL) was added dropwise to (3-carboxypropyl)triphenylphosphoium bromide (17 g, 40 mmol) in anhydrous DMSO (20 mL) under nitrogen at 24° C., and the solution was stirred 30 min before addition of 3-bromobenzaldehyde (4.7 mL, 40 mmol). After several minutes a precipitate was observed and an additional 20 mL of DMSO was added to aid salvation, and the reaction was stirred 18 hours. The solution was poured onto water (120 mL) and washed with chloroform. The aqueous layer was acidified with conc. HCl and extracted with chloroform (3×250 mL). The organic phase was concentrated and applied to a 65 (M) Biotage® silica gel column; Gradient elution from 15-65% B (A=Hexanes; B=EtOAc) over 2 L to give Example 1, (E)-5-(3-bromophenyl)pent-4-enoic acid 8.2 g (82%). 1H NMR (300 MHz, CDCl3) δ 7.45 (t, J=1.5 Hz, 1H), 7.30 (dt, J=7.7, 1.5 Hz, 1H), 7.2-7.16 (m, 1H), 7.12 (t, J=7.7 Hz, 1H), 6.40-6.32 (m, 1H), 6.23-6.14 (m, 1H), 2.52 (s, 4H). RT=2.0 minutes (condition 1); LRMS: Anal. Calcd. for C11H11BrO2: 252.97. found: 252.98 (M−H).

1. waitAfter several minutes a precipitate was observed
2. additionThe solution was poured onto water (120 mL)
3. washwashed with chloroform
4. extractionextracted with chloroform (3×250 mL)
5. concentrationThe organic phase was concentrated
6. washGradient elution from 15-65% B (A=Hexanes