title: Synthesis of 6- and 8-alkynylated purines and their ribonucleosides by the coupling of halopurines with alkynes.
abstract: Coupling reaction of 6-iodo- or 6-chloropurine with alkynes in the presence of (PPh3) 2PdCl2-CuI catalyst in triethylamine to give 6-alkynylated purines was achieved by the use of dipolar aprotic solvent as co-solvent. Under the reaction conditions, ribonucleoside as well as its tri-O-acetate of 6-chloropurine also gave the corresponding alkynylated products in high yields. Though similar reaction for 8-bromo-derivatives of adenine and guanine gave poor yields, the 8-alkynylated free bases could be obtained by acid hydrolysis of the alkynylated ribonucleosides. 6-Alkynylated purines exhibited moderate to weak cytokinin activity in Amaranthus test.
mesh_terms: D000480:Alkynes; D007202:Indicators and Reagents; D008722:Methods; D011684:Purine Nucleosides / Q000138:chemical synthesis; D011687:Purines / Q000138:chemical synthesis*; D012263:Ribonucleosides / Q000138:chemical synthesis; D013329:Structure-Activity Relationship
chemical_list: D000480:Alkynes; D007202:Indicators and Reagents; D011684:Purine Nucleosides; D011687:Purines; D012263:Ribonucleosides; C005248:nebularine