Diisopropylamine → 5-(Benzyloxy)-2-fluoropyridin-3-ylboronic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of diisopropylamine (Aldrich) (0.33 mL, 2.16 mmol) in THF (5 mL) was cooled to 0° C. and treated with n-butyllithium (Aldrich) (0.94 mL, 2.36 mmol). The resulting mixture was stirred at 0° C. for 30 min and then cooled to −78° C. 5-(Benzyloxy)-2-fluoropyridine (Aldrich) (0.200 g, 0.982 mmol) in THF (3 mL) was added dropwise and the solution was stirred at −78° C. for 40 min before being treated with triisopropyl borate (Aldrich) (0.50 mL, 2.16 mmol) in THF (2 mL). After the addition, the cooling bath was removed and the reaction mixture slowly warmed up to rt and was stirred for 1 h. The reaction mixture was quenched with 5% NaOH (10 mL). The aqueous layer was separated and acidified to pH 5 using 5N HCl. The resulting mixture was extracted with EtOAc (2×15 mL). The combined organic extracts were dried over MgSO4 and concentrated to give the crude product as yellow solid (0.210 g). m/z (ESI, +ve ion) 248.0 (M+H)+. 1H NMR (300 MHz, d4-MeOH) δ 6.60 (br s., 1H); 6.36 (br. s., 1H); 6.00-6.24 (m, 5H); 3.87 (s, 2H).

Herkunft & Nachweise