MODIFIED ULLMANN COUPLING OF 2-CHLORO-3-TRIFLUOROMETHYLPYRIDINE

The application of the modified Ullmann reaction to 2-chloro-3-trifluo romethylpyridine furnishes 5,5'-bis(trifluoromethyl)-2,2'-bipyridine a s the primary product, accompanied by small amounts of the expected 3, 3'-bis(trifluoromethyl)-2,2'-bipyridine, 2-benzyl-3-(trifluoromethyl)p yridine, bibenzyl, 3-trifluoromethylpyridine, 3-methylpyridine, 2-hydr oxyethyl-(3-trifluoromethylpyridyl) ether and 2-hydroxyethyl-(3-methyl pyridyl) ether. For comparison purposes, a sample of 3,3'-bis-(trifluo romethyl)-2,2'bipyridyl was prepared by the treatment of 2,2'-bipyridy l-3,3'-dicarboxylic acid with sulfur tetrafluoride. The formation of a ll but two compounds mentioned above can be rationalized on the basis of the single-electron-transfer process.