ChemicalBook CAS DataBase List 4-N-Boc-amino-3-fluorophenylboronic acid

4-N-Boc-amino-3-fluorophenylboronic acid synthesis

4synthesis methods

Product Name:4-N-Boc-amino-3-fluorophenylboronic acid
CAS Number:218301-87-2
Molecular formula:C11H15BFNO4
Molecular Weight:255.05

209958-42-9
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$30.00/1/ G

4-N-Boc-amino-3-fluorophenylboronic acid

218301-87-2
77 suppliers
$69.00/500mg

Yield:218301-87-2 74%

Reaction Conditions:

Stage #1: tert-butyl N-(4-bromo-2-fluorophenyl)carbamatewith n-butyllithium in tetrahydrofuran at -85; for 1 h;
Stage #2: with Trimethyl borate in tetrahydrofuran at -90 - 20;
Stage #3: with water;acetic acidmore than 3 stages;

Steps:

A.2

Step 2The solution of the product from step 1 (25 g, 86 mmol) in THF (400 mL), was cooled to -85 ⁰C, and then treated dropwise with 83 mL of 2.5 M n-BuLi (208 mmol). The mixture was stirred for 1 h, and quenched with trimethylborate (27 g, 260 mmol) at -90 °C. The viscous mixture was gradually warmed to rt, poured into 1 L of water, extracted with benzene (50 mL) and evaporated. The aqueous layer was neutralized with acetic acid, upon which the precipitated oil slowly started to crystallize. The precipitate was filtered off, washed with water and air-dried yielding 15g of the boronic acid. The aqueous filtrate was extracted with EtOAc, the organic layers were combined, dried and evaporated to dryness. Flash column chromatography (PhH - PhH: EtOH 3:1 ) yielded another batch of the boronic acid (1.2 g) improving the combined yield to 74% (64 mmol).¹H-NMR (DMSO, 300 MHz): 9.00 (s, 1 H); 8.20 (br. s, 2 H); 7.62 (t, 1 H); 7.48 - 7.54 (m, 2 H); 1.50 (s, 9 H).

References:

WO2007/147574,2007,A1 Location in patent:Page/Page column 55-56