8-Bromination of 2,6,9-trisubstituted purines with pyridinium tribromide

2,6,9-Trisubstituted purines are brominated in high yields using pyridinium tribromide as the brominating reagent. This procedure works excellently for electron-rich purines having electron-donating substituents at the 2- and 6-positions. The use of pyridinium tribromide, a crystalline alternative to elemental bromine, improves the bromination procedure for this type of substrate as the reagent is easy to handle and the work-up and purification procedures are simplified.