Trimethyl orthoacetate → 5-Methoxy-2-methylbenzoxazole
Reaction equation
[NH2:1][C:2]1[CH:7]=[C:6]([O:8][CH3:9])[CH:5]=[CH:4][C:3]=1[OH:10].[C:11](OC)(OC)(OC)[CH3:12]>>[CH3:9][O:8][C:6]1[CH:5]=[CH:4][C:3]2[O:10][C:11]([CH3:12])=[N:1][C:2]=2[CH:7]=1Participants
3
Procedure
A solution of 2-amino-4-methoxyphenol 17 (8 g, 57.4 mmol) in trimethyl orthoacetate 18 (50 mL) was heated to reflux and allowed to stir for 24 h. The reaction was allowed to cool and the excess 18 was evaporated (in vacuo). The residue was dissolved in ethyl acetate and washed with water. The organic layer was dried over MgSO4 and treated with activated carbon Norit A. The resulting solution was filtered through Celite 521 and evaporated to yield an oil. The oil was chromatographed on silica gel (20% ethyl acetate/hexanes) to yield compound 19 as a light yellow solid. Synthesis of 2-methyl-5-oxiran-2-ylmethoxybenzoxazole (67):
Workup
- temperatureto reflux
- temperatureto cool
- customthe excess 18 was evaporated (in vacuo)