反应详情

To a stirring solution consisting of dimethyl methylphosphonate (23.37 g, 188.4 mmol) in THF (400 mL) at −78° C. was slowly added n-butyllithium solution (112 mL, 179 mmol, 1.6 M solution in hexane). The reaction mixture was stirred for 30 minutes, after which time, (S)-(+)-ethyl 2-methyl-5-phenylpentanoate (14mb(i), 28.1 g, 94.2 mmol) in THF (100 mL) was slowly added. The resulting reaction mixture was stirred at −78° C. for two hours and was then allowed to rise to room temperature overnight. The reaction mixture was treated with 5% KHSO4 and extracted with ethyl acetate three times. The organic layer was washed twice with 50:50 water-brine and the organic layer was dried over sodium sulfate, filtered, and concentrated under vacuum. The residue was purified by silica gel chromatography. Elution with ethyl acetate-heptane (60:40 v/v) afforded the title compound (11.9 g, 42%) as a clear oil, pure of unrelated components; TLC Rf 0.22 (solvent system: 60:40 v/v ethyl acetate-heptane); HPLC retention time 14.5 minutes, 5μ Chiralpak IA 250×4.6 mm, ultraviolet detector at 210 nm, 1 mL/min, chiral purity 97.8% (S), 2.19% (R); MS (ESI−) m/z 297.1 (M−H)−; 1H NMR (CDCl3) δ 7.28-7.21 (m, 2H), 7.17-7.12 (m, 3H), 3.76-3.71 (m, 6H), 3.10 (d, J=2.20 Hz, 1H), 3.04 (d, J=2.20 Hz, 1H), 2.79-2.70 (m, 1H), 2.54-2.62 (m, 2H), 1.74-1.54 (m, 3H), 1.42-1.24 (m, 1H), 1.07 (d, J=6.96 Hz, 3H); [α]Tλ=α/cl, [α]21.9D=+0.084/(0.0169 g/1.5 mL)(0.5)=+14.91° (c=1.13, CHCl3).

1. customThe resulting reaction mixture
2. stirringwas stirred at −78° C. for two hours
3. waitto rise to room temperature overnight
4. extractionextracted with ethyl acetate three times
5. washThe organic layer was washed twice with 50:50 water-brine
6. dry with materialthe organic layer was dried over sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated under vacuum
9. customThe residue was purified by silica gel chromatography
10. washElution with ethyl acetate-heptane (60:40 v/v)