Reaction #73843

Reaction equation

2,3-dichloropyrazine

4-fluorophenyl boronic acid

cesium carbonate

tricyclohexylphosphine

→

2-chloro-3-(4-fluorophenyl)pyrazine

Yield 55.0%

Solvents

dioxane

Conditions

Workup

1. 1
   workup.ADDITIONwere added
2. 2
   Otherthey were reacted at 85° C. for 11 hours
3. 3
   OtherAfter the reaction
4. 4
   Filtrationfiltrated
5. 5
   workup.DISTILLATIONA solvent of the obtained filtrate was distilled off

Procedure

First, 5.06 g of 2,3-dichloropyrazine, 5.23 g of 4-fluorophenyl boronic acid, 22.16 g of cesium carbonate, and 200 mL of dioxane were put in a three-neck flask equipped with a reflux pipe, and 0.467 g of tris(dibenzylideneacetone)dipalladium(0) (abbreviation: Pd2(dba)3) and 2.5 mL of tricyclohexylphosphine (abbreviation: Cy3P) were added thereto while the mixture was stirred under a nitrogen atmosphere, and they were reacted at 85° C. for 11 hours. After the reaction, the reaction solution was cooled down to room temperature and filtrated. A solvent of the obtained filtrate was distilled off, and the obtained residue was refined with a column chromatography using dichloromethane as a development solvent, so that 2-chloro-3-(4-fluorophenyl)pyrazine was obtained (light yellow powder, yield: 55%). A synthesis scheme of Step 1 is shown by the following (a1-1).

Source