Acetyl chloride → 5-Acetyl-2,3-dimethylthiophene

Participants

Reaction Conditions

Reaction Steps

A solution of 5 (15.16 g, 135 mmole) and acetyl chloride (9.6 mL, 135 mmole) in 60 mL benzene dried over Na was cooled to −5° C. and vigorously stirred during the addition of a solution of tin (IV) chloride in 50 mL benzene over a period of 1 hour. The reaction mixture was removed from the cold bath and stirred for an additional hour at room temperature. The slow addition of 4 mL concentrated HCl in 28 mL water quenched the reaction. The organic layer was separated, washed with 2×10 mL water, dried over Na2SO4 and evaporated to give 20.8 g of crude product. Chromatography on a column of silica eluted with pet. ethenethyl acetate (10:1) and evaporation of relevant fractions gave a viscous yellow oil, 16.42 g, 79%. 1H NMR (CDCl3) δ: 2.08, s, 3H, COCH3; 2.31, s, 3H, CH3; 2.41, s, 3H, CH3; 7.33, s, 1H, H-3. 13C NMR (CDCl3) δ: 13.3, 13.7, 26.1, 134.7 135.3, 139.1, 143.4, 190.0.

Provenance & Evidence