Hydrochloric Acid → 4-(N-tert-butylcarbonyl-3-fluoropropylaminomethyl)phenyl boronic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of bromide 115 (3.0 g, 8.7 mmol) in anhydrous THF (30 mL) at −78° C. was added a 2.5 M solution of n-BuLi in hexane (3.64 mL, 9.1 mmol, 1.05 equiv). The resulting reaction mixture was stirred at −78° C. for 1 h before trimethyl borate (B(OMe)3, 1.2 mL, 10.4 mmol, 1.2 equiv) was added dropwise. The resulting reaction mixture was stirred at −78° C. for 0.5 h before being gradually warmed to room temperature overnight. The reaction mixture was poured into water (60 mL), and the aqueous solution was treated with 1.0 N aqueous HCl to pH 4.0. The aqueous mixture was then extracted with EtOAc (4×30 mL). The combined organic extracts were washed with saturated aqueous NaCl (30 mL), dried over anhydrous Na2SO4, and concentrated in vacuo to obtain the desired 4-(N-tert-butylcarbonyl-3-fluoropropylaminomethyl)phenyl boronic acid 120 (2.5 g). This product was directly used in subsequent reactions without further purification. C15H23BFNO4, HPLC/MS (ESI) role 312 (M++H).

Provenance & Evidence