ethyl 2,4-dibromobutanoate

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: To a solution containing 2-chloro-4-fluoro-5-nitrophenol (1 equivalent) and ethyl 2,4-dibromobutanoate (1 equivalent) in DMF is added potassium carbonate (1 equivalent) at room temperature and the mixture is stirred. After completion of the reaction, to the reaction mixture is added aqueous diluted hydrochloric acid and the mixture is extracted with ethyl acetate. After concentrating the organic layer, the residue is subjected to chromatography to give ethyl 2-(2-chloro-4-fluoro-5-nitrophenoxy)-4-bromobutanoate. After completion of the reaction the mixture is extracted with ethyl acetate After concentrating the organic layer

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: (Wasserman, H. H. et al. J Org. Chem. 1981, 46(15), 2991-2999). A mixture of (±)ethyl 2,4-dibromobutanoate (39) (15 g, 54.8 mmol), triethylamine (16.6 g, 164 mmol) and benzylamine (5.87 g, 54.8 mmol) was heated to reflux for 3 hours then concentrated under reduced pressure to give a solid suspension. Water (150 ml) was then added and the mixture extracted with ether (2×100 ml). The organic phase was dried and then concentrated under reduced pressure and the residue purified by dry flash chromatography on silica (hexanes then 1:3 ethyl acetate/hexanes) to give 40 as a pale yellow oil (6.3 g, 53%); 1H NMR (300 MHz, CDCl3) δ 7.37-7.27 (m, 5H), 4.16-4.03 (m, 2H), 3.82 (d, J=12.6 Hz, 1H), 3.73 (dd, J=8.4, 8.4 Hz, 1H), 3.61 (d, J=12.8 Hz, 1H), 3.34 (ddd, J=7.4, 7.4, 2.0 Hz, 1H), 2.95 (ddd, J=7.4, 7.4, 7.4 Hz, 1H), 2.44-2.31 (m, 1H), 2.27-2.16 (m, 1H), 1.20 (t, J=7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3) δ 172.5, 137.1, 129.0, 128.7, 128.2, 127.1, 64.5, 62.4, 60.5, 50.8, 21.5, 14.0. was heated to reflux for 3 hours then concentrated under reduced pressure to give a solid suspension the mixture extracted with ether (2×100 ml) The organic phase was dried concentrated under reduced pressure the residue purified by dry flash chromatography on silica (hexanes