Dichotomy in Regioselective Cross-Coupling Reactions of 6,8-Dichloropurines with Phenylboronic Acid and Methylmagnesium Chloride: Synthesis of 6,8-Disubstituted Purines
作者:Michal Hocek、Dana Hocková、Hana Dvořáková
DOI:10.1055/s-2004-816012
日期:——
Pd-catalyzed cross-coupling reaction of 6,8-dichloro-9-(tetrahydropyran-2-yl)purine with one equivalent of phenylboronic acid proceeded regioselectively to give 8-chloro-6-phenylpurine, while the analogous Fe-catalyzed reaction with methylmagnesium chloride gave the 6-chloro-8-methylpurine derivative as major product. Both types of the monochloropurine intermediates were subjected to other cross-coupling
Pd催化的6,8-二氯-9-(四氢吡喃-2-基)嘌呤与1当量苯基硼酸的交叉偶联反应区域选择性地进行,得到8-氯-6-苯基嘌呤,而类似的Fe催化反应与甲基氯化镁得到6-氯-8-甲基嘌呤衍生物作为主要产物。两种类型的单氯嘌呤中间体都经过其他交叉偶联反应或亲核取代,得到 9-(四氢吡喃-2-基)-6,8-二取代的嘌呤,这些嘌呤很容易脱保护为 8-取代的 6-苯基嘌呤或 6-取代的嘌呤8-甲基嘌呤。与苄基氯化镁和苯基溴化镁进行的类似反应得到了低转化率和低选择性。