Cross-coupling synthesis of alkyl (dialkylphenyl) indenes
A cross-coupling synthesis of 2-alkyl-4-(2,6-dialkylphenyl)indenes is described. A 2-alkylidene is treated with a dialkylboronic acid in the presence of a catalyst. A feature of the invention is the use of a cross-coupling catalyst comprising palladium dichloride (1,5-cyclooctadiene) as a cross-coupling catalyst.
1. A method for the synthesis of an alkyl(dialkylphenyl)indene which comprises treating a 2-alkyl haloindene with a dialkylboronic acid in a non-interfering solvent in presence of a cross-coupling catalyst.
2. The method of claim 1 , wherein said cross-coupling catalyst comprises palladium dichloride cyclooctadiene.
3. The method of claim 1 , wherein said non-interfering solvent is a hydrocarbon.
4. The method of claim 1 , wherein said 2-alkyl haloindene is 2-alkyl-4-chloroindene.
5. The method of claim 1 , wherein said dialkylboronic acid is a 2,6-dialkylphenyl boronic acid.
6. A method for synthesizing a 2-alkyl-4-(2,6-dialkyiphenyl) indene which comprises treating 2-alkyl-4-halo indene with a 2,6-dialkylboronic acid in the presence of a cross-coupling catalyst in a non-interfering hydrocarbon solvent.
7. The method of claim 6 , wherein said cross-coupling catalyst comprises palladium dichloride and 1,5-dicyclooctadiene.
8. The method of claim 1 , wherein said treating is conducted in a reflux temperature.
9. The method of claim 6 , wherein the mole ratio of said 2-alkyl-4-halo indene to said 2,6-dialkylboronic acid is from about 1:1.3 to about 1:1.75.
10. The method of claim 6 , wherein said 2-alkyl-4-halo indene is 2-methyl-4-chloro indene.
11. The method of claim 6 , wherein said 2,6-dialkylboronic acid is 2,6-dimethylboronic acid.
12. The method of claim 2 , wherein said non-interfering solvent is a hydrocarbon.
13. The method of claim 2 , wherein said 2-alkyl haloindene is 2-alkyl-4-chloroindene.
14. The method of claim 2 , wherein said dialkylboronic acid is a 2,6-dialkylphenyl boronic acid.
15. The method of claim 6 , wherein said treating is conducted in a reflux temperature.