Reaction #76437

Reaction equation

Boron tribromide

N-(4-chloro-3-methylisothiazol-5-yl)-2-(4-methoxyphenyl)propionamide

→

N-(4-chloro-3-methylisothiazol-5-yl)-2-(4-hydroxyphenyl)propionamide

Yield 99.4%

Solvents

dichloromethane

Conditions

Workup

1. 1
   workup.ADDITIONOnce the addition
2. 2
   Otherwas removed
3. 3
   TemperatureThe mixture was cooled to 0° C.
4. 4
   workup.ADDITIONexcess methanol added cautiously
5. 5
   OtherThe solvent was evaporated in vacuo
6. 6
   Otherthe residue was partitioned between ethyl acetate and brine
7. 7
   DryingThe organic layer was dried over anhydrous magnesium sulfate
8. 8
   Filtrationfiltered
9. 9
   Otherthe filtrate was evaporated in vacuo

Procedure

Boron tribromide (1.0 M solution in dichloromethane, 110 ml, 0.11 mol) was added dropwise to a stirred solution of N-(4-chloro-3-methylisothiazol-5-yl)-2-(4-methoxyphenyl)propionamide (125 g, 0.040 mol) in dichloromethane (200 ml) at −70° C. Once the addition was complete the cooling bath was removed and the mixture was allowed to warm to room temperature overnight. The mixture was cooled to 0° C. and excess methanol added cautiously. The solvent was evaporated in vacuo, and the residue was partitioned between ethyl acetate and brine. The organic layer was dried over anhydrous magnesium sulfate, filtered and the filtrate was evaporated in vacuo to give N-(4-chloro-3-methylisothiazol-5-yl)-2-(4-hydroxyphenyl)propionamide (11.8 g), which was used without further purification in the next step.

Source