p-Toluenesulfonic acid → 2,2-dimethyl-3,4-dihydro-2H-1,3-benzoxazin-4-one

Participants

Reaction Steps

To a solution of 3-hydroxy-benzamide (50 g, 0.36 mol) in acetone (300 mL) was added 2,2-dimethoxy-propane (100 mL) and p-toluene sulfonic acid (5 g, 0.03 mol) and the mixture was heated to reflux overnight. The solvent was evaporated under vacuum to give crude 2,2-dimethyl-2H-benzo[e][1,3]oxazin-4(3H)-one (55 g, 86%) that was used in the next step without further purification. 1H NMR (300 MHz, CDCl3) δ 7.91 (dd, J=1.8, 7.8 Hz 1H), 7.44 (t, J=7.8 Hz 1H), 7.35 (brs, 1H), 7.05 (t, J=7.8 Hz 1H), 6.91 (d, J=8.1 Hz 1H), 1.65 (s, 6H).

Provenance & Evidence