2-Fluoropyridine-5-boronic acid synthesis
- Product Name:2-Fluoropyridine-5-boronic acid
- CAS Number:351019-18-6
- Molecular formula:C5H5BFNO2
- Molecular Weight:140.91
766-11-0
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$6.00/5g
351019-18-6
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$11.19/1G
Yield:351019-18-6 81%
Reaction Conditions:
Stage #1:5-bromo-2-fluoropyridine with Triisopropyl borate in tetrahydrofuran;toluene at -50 - -35;
Stage #2: with n-butyllithium at -45 - -15; for 5 h;Product distribution / selectivity;
Steps:
3
Preparation of 6-fluoropyridin-3-ylboronic acid (4); [000254] A 72 L reactor equipped with reflux condenser, and temperature probe. To the reactor 5-bromo-2-fluoropyridine (1.17 L, 0.568 mol), toluene (18.2 L), and triisopropyl borate (3.13 L, 0.68 mol, 1.2 equiv.) were charged and stirred. Tetrahydrofuran (4.4 L) was added to the reactor and the reaction mixture was cooled to between -35 to -50 0C. While maintaining a temperature between -35 to -45 0C, n-butyl lithium (2.5 M solution of hexanes, 5.44 L, 0.68 mol, 1.2 equiv.) was cautiously added to the reactor. After 5 h, the reaction was deemed complete and the reaction mixture was warmed to between -15 to -20 0C. To the reaction was added 2M HCl (11.80L) to the reactor while maintaining a temperature between -15 0C and 0 0C. The reaction mixture was stirred at 18 to 23 0C for (16 h) and the phases were separated. The organics were then extracted with 6 M sodium hydroxide (6.0 L). The acidic anbasic aqueous phases were mixed in the reactor and 6 M HCl (2.5 L) was added until pH 7.5 was achieved. Sodium chloride (6.0 kg) was then added to the aqueous phase. The aqueous phase was then extracted with THF (3 * 20 L). The combined organics were dried with magnesium sulfate and concentrated to give 1300 g of a tan solid (81% crude yield).
References:
KINEX PHARMACEUTICALS, LLC WO2009/51848, 2009, A1 Location in patent:Page/Page column 65
766-11-0
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$6.00/5g
121-43-7
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$13.00/25mL
351019-18-6
324 suppliers
$11.19/1G
171197-80-1
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351019-18-6
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$11.19/1G
20511-12-0
463 suppliers
$6.00/1g
351019-18-6
324 suppliers
$11.19/1G