Pyridine → 8-Bromo-5-methoxy-3-chromanone

Participants

Reaction Steps

To a solution consisting of dry pyridine and CH2Cl2 (120 ml, dried over P2O5) CrO3 (435 mg, 4.35 mmol) was added. The mixture was stirred for 15 min and 8-bromo-5-methoxy-3-chromanol (293 mg, 1.13 mmol) was dissolved in 10 ml dry CH2Cl2 was added and immediately thereafter acetic acid anhydride (0.41 ml, 4.35 mmol) was added to the solution. The mixture was stirred for 10 min and then sucked through a short silica column (13 g SiO2) with vacuum. The column was washed with CH2Cl2 and the solvent evaporated yielding 237 mg (81%) of the product. An analytic sample was obtained from recrystallization in light petroleum-ether, m.p. 97°-100° C. 1H NMR (CHCl3) δ 3.55 (s,2H), 3.80 (s,3H), 4.45 (s,2H), 6.5 (d,1H), 7.4 (d,1H). GC/M (HP-5970A) m/e=258 (64) M+1, 256 (57) M-1, 134 (100), 50 (11), 76 (11).

Provenance & Evidence