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The Suzuki-Miyaura reaction of 9-unsubstituted 2-, 6-, and 8-halopurine bases with diverse aryl-and alkenylboronic acids in water-acetonitrile mixtures under microwave irradiation was used for the single-step synthesis of arylpurines. In most cases the product crystallized directly from the reaction mixture in high yields and good purity. The scope and limitations of these reactions were studied. 1 Introduction 2 Results and Discussion 2.1 Cross-Coupling Reactions of 6-Chloro-9H-purine 2.2 Cross-Coupling Reactions of 2-Amino-6-chloro-9H-purine 2.3 Cross-Coupling Reactions of 8-Bromoadenine 2.4 Cross-Coupling Reactions of 2-Chloroadenine 2.5 Cross-Coupling Reactions of 2,6-Dichloro-9H-purine 2.6 NMR Analysis of Arylpurines and Determination of Regioselectivity 3 Conclusions 4 Experimental Section 5 References

Purine derivatives R 0540Cross-Coupling Reactions of Halopurines with Aryl-and Alkyltrifluoroborates. The Scope and Limitations in the Synthesis of Modified Purines. -Optimized reaction conditions are developed for the Pd-catalyzed cross-coupling reaction of halopurines with aryltrifluoroborates. In general, alkyl-substituted (II) show poor reactivity. -(HASNIK, Z.; POHL, R.; HOCEK*, M.; Synthesis

A novel approach to the synthesis of (purin-6-yl)acetates was developed based on Pdcatalyzed cross-coupling reactions of 6-chloropurines with a Reformatsky reagent. Their reduction with NaBH 4 and treatment with MnO 2 gave 6-(2-hydroxyethyl)purines, while reactions with amines in presence of NaCN afforded 6-(carbamoylmethyl)purines. Mesylation of the 6-(2-hydroxyethyl)purines followed by nucleophilic substitutions gave rise to several 6-(2-substituted ethyl)purines. This methodology was successfully applied to the synthesis of substituted purine bases and nucleosides for cytostatic and antiviral activity screening. None of the compounds exerted significant activity.