Synthesis of optically active 6-alkynyl- and 6-alkylpurines as cytokinin analogs and inhibitors of 15-lipoxygenase; Studies of intramolecular cyclization of 6-(hydroxyalkyn-1-yl)purines

Optically active 6-alkynyl- and 6-alkylpurines have been synthesized. These compounds can be regarded as analogs of cytokinin plant growth hormones. The analogs were examined as growth stimulators and as inhibitors of 15-lipoxygenase (15-LO). The (S)-enantiomer of 6-(5-hydroxy-4-methylpent-1-yl)purine exhibited profound growth stimulation activity, especially at low concentrations. 6-(Hydroxyalkyn-1-yl)purines were found to cyclize by nucleophilic exo attack from the hydroxy group at the triple bond. (Z)-Isomers were formed under acidic conditions. Plant growth stimulators and 15-LO inhibitors were identified among the cyclization products. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.