Dimethyl Sulfoxide → 3-(2-Fluorophenyl)prop-2-ynal

Participants

Reaction Conditions

Reaction Steps

To a solution of oxalyl chloride (102 mL, 1.18 mol, 1.2 equiv) in CH2Cl2 (3L) at −78° C. was slowly added DMSO (167 mL, 2.35 mol, 2.4 equiv) while keeping the reaction temperature below −59° C. The mixture was stirred for 10 min and treated with a solution of 3-(2-fluorophenyl)prop-2-yn-1-ol (147 g, 0.98 mol) in CH2Cl2 (100 mL), keeping the reaction temperature below −65° C. The resulting thick white slurry was stirred for 15 min, then treated with Et3N (682 mL, 4.90 mol, 5 equiv). After 10 min the reaction mixture was allowed to warm to 0° C. and treated with water (2 L). The organic layer was washed with water (3×1L), dried (Na2SO4) and concentrated under reduced pressure to afford 3-(2-fluorophenyl)prop-2-ynal (148 g, 100%) as a brown oil which was stored suspended in frozen benzene (0.5 L): 1H NMR (CDCl3) δ 7.03-7.14 (m, 2H), 7.37-7.52 (m, 2H), 9.36 (s, 1H); 13C NMR (CDCl3) δ 88.1, 92.4 (d, JC−F=2.4 Hz, 1C), 108.2 (d, JC−F=14.5 Hz, 1C), 115.9 (d, JC−F=19.6 Hz, 1C), 124.4 (d, JC−F=3.6 Hz, 1C), 133.3 (d, JC−F=8.5 Hz, 1C), 134.8 162.6 (d, JC−F=246.3 Hz, 1C), 176.4; GCMS m/z (rel abundance) 149 (MH+, 75%).

Provenance & Evidence