Methyl 5,6-dibromonicotinate synthesis
- Product Name:Methyl 5,6-dibromonicotinate
- CAS Number:78686-81-4
- Molecular formula:C7H5Br2NO2
- Molecular Weight:294.93
381247-99-0
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Yield:78686-81-4 50%
Reaction Conditions:
with tetrabutylammomium bromide;phosphorus pentoxide in toluene; for 5 h;Reflux;
Steps:
118
Intermediate 118Methyl 5,6-dibromonicotinate Methyl 5-bromo-6-hydroxynicotininate (Intermediate 117, 10 g, 43 mmol) was suspended in toluene (100 mL) and phosphorous pentoxide (12 g, 43 mmol) was added. Tetrabutyl ammonium bromide (20 g, 62.1 mmol) was added and the reaction was stirred at reflux for 5 h. The reaction mixture was cooled to ~50°C and toluene was decanted from the solution. Toluene (50 mL) was added to the viscous oil and heated to reflux for 30 min. The reaction mixture was cooled to ~50°C and toluene was decanted from the solution. This process was repeated twice more, and the toluene extracts were combined. The toluene was washed with saturated bicarbonate (2x, 30 mL), and the solvent was removed in vacuo. The residue was chromatographed on silica gel using 10-50% ethyl acetate in heptane to give 6.3g (50%) of methyl 5,6-dibromonicotinate as an off white solid. MS (ESP): 295.8 (MH+) for C7H5Br2NO2 1H NMR (300 MHz, DMSO-d6): 3.91 (s, 3H), 8.51 (s, IH), 8.86 (s, 1 H).
References:
WO2009/106885,2009,A1 Location in patent:Page/Page column 297
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