Acetic Anhydride → HCID 10199432, compound

Participants

Reaction Steps

To a solution of 4-(2,3-dimethyl-naphtho[2,3-b]thiophen-4-yl)-2,6-dimethyl-phenol (24.0 g, 72.2 mmol) in pyridine (200 mL) at 0 C. under nitrogen was added dropwise acetic anhydride (8.9 mL, 93.9 mmol) over a period of 10 min. After 45 min at 0 C., the reaction mixture was placed in the freezer for 18 h, then removed and stirred for 2 h in an ice bath that was allowed to warm to room temperature. The reaction mixture was poured onto water (1 L) and acidified with 10% hydrochloric acid to a pH of 1. The resulting mixture was extracted with diethyl ether (1 L), which was washed with 10% hydrochloric acid (1 L), twice with water (1 L), brine (700 mL), and dried (MgSO4). Concentration under reduced pressure and chromatography with petroleum ether:ethyl acetate (97:3) gave the title compound as a cream solid (22.4 g, 79%): NMR (CDCl3): δ8.26 (s, 1H), 7.87 (d, 1H), 7.58 (d, 1H), 7.44-7.40 (m, 1H), 7.33-7.29 (m, 1H), 7.07 (s, 2H), 2.42 (s, 3H), 2.41 (s, 3H), 2.23 (s, 6H), 1.67 (s, 3H); MS(EI): [M+] 374; Anal. Calc. for C24H22O2S: C, 76.97; H, 5.92; N, 0.00. Found: C, 76.17; H, 5.75; N, 0.22.

Provenance & Evidence