Oxalyl chloride → 2,2-Difluoro-4-pentenoyl chloride

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Reaction Steps

Add oxalyl chloride (17.6 mL, 201.8 mmol) to compound 8c (25 g, 183.7 mmol) and dimethylformamide (3 drops) under neat conditions at room temperature. Observe gas evolution for approximately 2 h. After 5 h, treat the reaction mixture with an additional 0.08 eq of oxalyl chloride (1.2 mL) and stir for 18 h. Use fractional distillation (88°-91° C.) to obtain 24.4 g, 158 mmol of the title compound 8a as an oil in 85% yield. 19F NMR (CDCl3) δ -101.9 (t); 13C NMR (CDCl3) δ 167.3 (t, CO2H), 125.5 (s, C=C), 123.1 (s, C=C), 115.6 (t, CF2), 38.3 (t, CH2); 1H NMR (CDCl3) δ 2.90 (m, 2H), 5.33 (d, 1H), 5.36 (s, 1H), 5.74 (m, 2H).

Provenance & Evidence