REGULATORS OF CELL DIVISION IN PLANT TISSUES .7. SYNTHESIS OF ZEATIN AND RELATED 6-SUBSTITUTED PURINES

6-(4-Hydroxy-3-methylbut-trans-2-enylamino)purine (zeatin), a cytokinin isolated from Zea mays, has been synthesized by a new route. β-Methylcrotononitrile was brominated with N-bromosuccinimide yielding γ-bromo-β-methylcrotononitrile, from which trans-γ-acetoxy-β-methylcrotononitrile was prepared. The alcohol derived from this acetate was converted into trans-β-methyl-γ-(tetrahydropyran-2-yloxy)crotononitrile. Reduction and acid hydrolysis gave 4-amino-2-methylbut-trans-2-en-1-ol which was made to react with 6-chloropurine to yield zeatin. Several γ-alkoxy-β-methylcrotononitriles were prepared and reduced by aluminium chloride-lithium aluminium hydride to the corresponding unsaturated amines. Saturated nitrile formation also occurred in these reductions. The amines prepared were condensed with 6-chloropurine to yield a series of O-alkylzeatins. A number of other zeatin analogues were also synthesized. Two 6-methoxyalkylamino-purines were cleaved by sodium borohydride in the presence of iodine to 6-hydroxy-alkylaminopurines. © 1969, CSIRO. All rights reserved.