反应详情

温度

60 °C

The residue of 3-methoxycarbonyl-6-(4-chlorophenyl)-1,1,1-triphenyl-2-aza-1λ5-phosphahexa-1,3,5-triene (10.2 mmol) from Step D was dissolved in acetonitrile (40 mL) and 2,4-dichlorobenzaldehyde (1.78 g, 10.2 mmol) was added. The reaction was heated to 60° C. under a condenser (left open to the air) for 20 h. HPLC/MS indicated a mixture of the desired title pyridine and dihydropyridine intermediate 394 (M+1), 396 (M+3), Rt=4.75 min). The reaction was heated a further 4 h and was then concentrated. The residue was purified by flash column chromatography on silica gel eluted with 0 to 20% ethyl acetate in hexanes to afford methyl 6-(2,4-dichlorophenyl)-5-(4-chlorophenyl)pyridine-2-carboxylate. HPLC/MS: 392 (M+1), 394 (M+3); Rt=4.16 min. 1HNMR (CDCl3): δ 4.039 (s, 3H), 7.09 (br d, J=8.5 Hz, 2H), 7.26 (br d, J=8.4 Hz, 2H), 7.28 (d, J=2 Hz, 1H), 7.30 (dd, J=2.0 and 8.3 Hz, 1H), 7.34 (d, J=8.3 Hz, 1H), 7.90 (d, J=8 Hz, 1H), 8.26 (d, J=8.0 Hz, 1H).

1. temperatureThe reaction was heated a further 4 h
2. concentrationwas then concentrated
3. customThe residue was purified by flash column chromatography on silica gel
4. washeluted with 0 to 20% ethyl acetate in hexanes