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

Abstract

AbstractOptically 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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)