Carbamic acid, N-(2,5-dibromo-4-pyridinyl)-, 1,1-dimethylethyl ester synthesis
- Product Name:Carbamic acid, N-(2,5-dibromo-4-pyridinyl)-, 1,1-dimethylethyl ester
- CAS Number:1574395-46-2
- Molecular formula:C10H12Br2N2O2
- Molecular Weight:352.02
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Yield:1574395-46-2 41%
Reaction Conditions:
with diphenyl phosphoryl azide;triethylamine at 80;Inert atmosphere;Curtius Rearrangement;
Steps:
12.2 Step 2
A 20-L 4-necked round-bottom flask purged and maintained under a N2 atmosphere was charged with 2,5-dibromoisonicotinic acid (1.030 Kg, 3.67 mol, 1.00 equiv), TEA (484 g, 4.78 mol, 1.30 equiv), tert-butanol (10 L) followed by the addition of DPPA (1215 g, 4.41 mol, 1.20 equiv). The resulting solution was stirred overnight at 80° C. This reaction was repeated for 5 times. The resulting mixture was concentrated in vacuo, diluted with 20 L of water and extracted with 3×15 L of EtOAc. The organic layers were combined, washed with 2×15 L of brine, dried (Na2SO4), filtered and concentrated in vacuo. The residue was purified by SiO2 chromatography eluting with an EtOAc/petroleum ether gradient (1:30 to 1:15) to afford 3.2 Kg (41%) of tert-butyl 2,5-dibromopyridine-4-ylcarbamate (A-3) as a white solid
References:
US2014/66453,2014,A1 Location in patent:Paragraph 0272-0273
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