Application of palladacycle catalyst in the synthesis of mono‐arylpyridyl bromides

The mono-arylpyridyl bromides are very useful key intermediates that can be further functionalized to generate bioactive compounds. It is possible to obtain mono-arylation products of 3,5-dibromopyridine with high preferentiality and high yields by air- and moisture-stable palladacycle (catalyst II) catalyzed Suzuki reaction of 3,5-dibromopyridine with a series of arylboronic acids—ester under the conditions of K2CO3–toluene–methanol (4:1, v/v), reflux (75 °C), 5.6 equiv. of 3,5-dibromopyridine with the ratio (mono:bis) ranging from of 99:1 to 90:10. This new method could also be used to easily achieve pyridylpyridyl bond formation to afford 3-bromo-5-pyridylpyridine (3j). Copyright © 2007 John Wiley & Sons, Ltd.