The present invention provides for the preparation &bgr;-adenine nucleosides by coupling an adenine derivative containing an unprotected exocyclic amino group at the C-6 position and a blocked arabinofuranosyl derivative, in the presence of a base and solvent. The present invention also provides for the stereoselective preparation of 2-deoxy-&bgr;-D-adenine nucleosides wherein a blocked 2-deoxy-&agr;-D-arabinofuranosyl halide is coupled with the salt of an adenine derivative. The forgoing aspects of the present invention are utilized in the preparation of a clofarabine composition wherein the ratio of &bgr; to &agr;-anomer is at least 99:1.
本发明提供了一种通过在碱和溶剂的存在下,耦合含有未保护的外环
氨基基团的C-6位置
腺嘌呤衍
生物和阻滞的
阿拉伯糖核苷衍
生物来制备&bgr;-
腺嘌呤核苷的方法。本发明还提供了一种选择性立体构型制备2-脱氧-&bgr;-D-
腺嘌呤核苷的方法,其中阻滞的2-脱氧-&agr;-
D-阿拉伯糖苯基卤代物与
腺嘌呤衍
生物的盐耦合。本发明的上述方面被用于制备一种克洛法滨组合物,其中&bgr;与&agr;-异构体的比例至少为99:1。