Ammonium Chloride → Tert-butyl isopropyl(5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)thiazol-2-yl)carbamate

Participants

Reaction Conditions

Reaction Steps

A solution of tert-butyl 5-bromothiazol-2-yl(isopropyl)carbamate (Intermediate 43-1, 7.5 g, 23.3 mmol) in THF (50 mL) was treated with n-butyllithium (1.6 M in hexane, 21.8 mL, 34.88 mmol) dropwise at −78° C. The resulting solution was stirred at −78° C. for 10 min, then was treated dropwise with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (6.49 g, 34.9 mmol). The mixture was stirred at −78° C. for 2 h, then was warmed to rt and treated with 50% aqueous ammonium chloride (50 mL). The mixture was extracted with EtOAc (100 mL) and the organic layer was washed with water and brine, and dried and concentrated. The residue was slurried in hexane (30 mL) and the precipitate was collected by filtration, washed with hexane (20 mL) and dried to give tert-butyl-isopropyl(5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)thiazol-2-yl)carbamate as a yellow solid (4.17 g, 48%). 1H NMR (400 MHz, chloroform-d) δ 7.95 (s, 1H) 5.37 (m, 1H) 1.60 (s, 9H) 1.44 (d, 6.7 Hz, 6H) 1.34 (s, 12H).

Provenance & Evidence