摘要:
Pd-catalysed reactions of 2-Cl, 2-Br and 2-I derivatives of a 6-chloropurine nucleoside with benzamide have been compared, using Pd(2)dba(3), Xantphos and Cs2CO3 in toluene, between 20 and 80 degrees C. The reactivity order was 2-I > 2-Br > 6-Cl >> 2-Cl. The 2-I substituent could be replaced even at 0 degrees C, under conditions disclosed here for the first time. On the other hand, the replacement of the chlorine atom at position 2 (2-Cl) required 110 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.