Toluene → 2-(4-Bromophenyl)benzo(d)oxazole

Reaction equation

[Br:1][C:2]1[CH:17]=[CH:16][C:5]([C:6]([NH:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[OH:15])=O)=[CH:4][CH:3]=1.O.C1(C)C=CC(S(O)(=O)=O)=CC=1.C1(C)C=CC=CC=1>O>[Br:1][C:2]1[CH:17]=[CH:16][C:5]([C:6]2[O:15][C:10]3[CH:11]=[CH:12][CH:13]=[CH:14][C:9]=3[N:8]=2)=[CH:4][CH:3]=1

Participants

Procedure

5.3 g (18 mmol) of 4-bromo-N-(2-hydroxyphenyl)benzamide, 8.0 g (46 mmol) of para-toluenesulfonic acid monohydrate, and 200 mL of toluene were put in a 300 mL three-neck flask. The mixture was refluxed for 4 hours under a nitrogen stream. After a certain time, water was added to the mixture, and an organic layer and an aqueous layer was extracted with ethyl acetate. The resulting extract was combined with the organic layer, and the organic layer was washed with a saturated aqueous solution of sodium bicarbonate and then a saturated saline, and dried with magnesium sulfate. The obtained mixture was subjected to suction filtration through Celite (produced by Wako Pure Chemical Industries, Ltd., Catalog No. 531-16855), and the filtrate was condensed to obtain a solid. The obtained solid was recrystallized with ethyl acetate/hexane, so that 3.1 g of target white powder was obtained with a yield of 61%.