Preparation of 6-Aryl- and 6-Heteroarylpurines by [2+2+2]-Cyclotrimerizations

Preparation of 6-Aryl- and 6-Heteroarylpurines by [2+2+2]- Cyclotrimerizations Mgr. Pavel Turek Dept. of Organic and Nuclear Chemistry, Faculty of Science, Charles University Prague 2009 The aim of my project was to synthesize new potentially biologically active arylpurines by transition metal catalyzed or mediated [2+2+2]-cyclotrimerization reactions. This approach should enable to assemble various structural motives attached to the purine skeleton. The main targets were 6-arylpurines. 6-Arylpurine derivatives have diverse types of a biological activity: some substituted 6-arylpurine bases are antagonists of corticotropin-releasing hormone or possess antimycobacterial and antibacterial activity, while 6-arylpurine ribonucleosides are potent cytostatics. These facts explain, why it is worth being interested in synthesis of this class of compounds. Until now 6-arylpurines have been mostly prepared by cross-coupling reactions of 6- halopurines with various organometallic compounds, but this approach is limited by factors like availability, reactivity and stability of the corresponding arylmetals. The synthetic strategy used in my project was based on a transition metal catalyzed or mediated cyclotrimerization of alkynes. Generally, these methods enable to assemble aromatic and heteroaromatic compounds from..