Hydrochloric Acid → (2-Bromopyridin-3-yl)-(2-chlorophenyl)methanone

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Add n-butyllithium (21.7 mL, 34.8 mmol, 1.6 M in hexanes) to a −70° C. solution of diisopropylamine (4.9 mL, 34.8 mmol) in THF (75 mL). Allow the solution to cool back to −70° C., and add 2-bromopyridine (5.0 g, 31.6 mmol) to the solution while maintaining the temperature below −65° C. Rinse contents of vessel that contained 2-bromopyridine with THF (10 mL) and add this solution to the reaction mixture. Stir the resulting solution for 15 min, and then add a solution of 2-chlorobenzaldehyde (3.55 mL, 31.6 mmol) in THF (15 mL) in a single portion. Stir the resulting solution for approximately 5 h at −70° C. Add MeOH (3.0 mL) and remove cooling. Add 3 N HCl (30 mL) to the reaction mixture followed by toluene (25 mL). Separate the layers, and wash the organic layer with H2O (25 mL). Concentrate the organic layer to approximately 2 total volumes. Add toluene (50 mL) and concentrate the solution to approximately 2 total volumes. Add toluene (65 mL) again, and concentrate the solution to approximately 2 total volumes. Add DMSO (18 mL). Add N,N-diisopropylethylamine (14.5 mL, 83.1 mmol) to the resulting solution. In a separate reaction vessel, dissolve sulfur trioxide pyridine complex (11.6 g, 72.7 mmol) in DMSO (50 mL). Add a portion of the sulfur trioxide pyridine complex/DMSO solution (35 mL) to the reaction mixture and stir for 30 min. Add a second portion of the sulfur trioxide pyridine complex/DMSO solution (9 mL) to the reaction mixture and stir for 30 min. Add a third portion of the sulfur trioxide pyridine complex/DMSO solution (9 mL) and stir for 30 min. Add a final portion of the sulfur trioxide pyridine complex/DMSO solution (approximately 9 mL) and stir for 30 min. Add ethyl acetate (50 mL) and 1 N HCl (100 mL). Separate the layers and extract the aqueous layer with ethyl acetate (25 mL). Separate the layers and extract the combined organic layers with H2O (25 mL). Separate the layers and concentrate the organic layer to approximately 2 total volumes. Add isopropanol (50 mL) and concentrate the resulting solution to approximately 2 total volumes. Add isopropanol (50 mL) and concentrate the resulting solution to approximately 2 total volumes. Add isopropanol (5 mL), and then add heptane (40 mL) dropwise. Stir the resulting slurry for 15 min. Cool the slurry to 0° C. and stir for 1 h. Filter the slurry, rinse the filter cake with chilled heptane (20 mL), and dry to afford the title compound as an off-white solid: 1H NMR (500 MHz, CDCl3) δ 8.49 (dd, J=4.9, 2.0 Hz, 1H), 7.78 (dd, J=7.3, 2.0 Hz, 1H), 7.59 (dd, J=7.3, 1.5 Hz, 1H), 7.49-7.36 (m, 4H); 13C NMR (125 MHz, CDCl3) δ 193.8, 152.0, 139.5, 139.1, 137.7, 136.7, 133.6, 133.3, 131.8, 131.2, 127.4, 123.0. LRMS (ES+) calcd for C12H8BrClNO (M+H+) 295.9, found 295.8 m/z.

Herkunft & Nachweise