Zeatin, synthesis

Occurrence, chemistry, synthesis and cytokinin activity of l -methyl-rran.s-zeatin and its analogs (glycosylated adenine derivatives) 97H(46)659. 

Zearalenone growth promotant veterinary use, 1, 219 ( )-Zearalenone synthesis, 1, 479 Zeatin... 

There are good reasons presently for believing also that free cytokinins have important biological activity independently of any direct association with tRNA (1) there are results showing direct effects of exogenous cytokinin independently of any apparent incorporation into tRNA (2) ethanolic extracts of corn kernels contain the trans-isomer of zeatin, while the tRNA hydrolysates of corn kernels contain the cis-isomer, suggesting that zeatin is not a precursor in the synthesis of tRNA in that material (3) dihydrozeatin... 

Leonard et al. have used the major adduct from isoprene cycloaddition to a chloronitroso compound in an efficient total synthesis of the cell division stimulant c/j-zeatin [Eq. (13)]. ... 

The only report of an effort to develop a functional assay for a cytokinin receptor is the work in barley by Kulaeva et al. [54-56]. They isolated CBPs, added them to isolated nuclei and looked for a stimulation in RNA synthesis. They isolated three different CBPs of 28-30, 40 and 67 kD. The 28-30 and 67 kD proteins were purified on BA-Sepharose and zeatin-Sepharose, respectively. Both proteins were able to stimulate total RNA synthesis by 2-3 fold only in presence of cytokinins (100 nM). The 67 kD protein activated polymerase I and II dependent transcription specifically with trans and not cis-zeatin. However, the binding affinities and specificities for other cytokinins were not indicated, therefore, this report needs to be viewed with some caution until it can be carefully reproduced with added controls. 

A new synthesis of trans-4-amino-l-hydroxy-2-methylbut-2-ene, an intermediate in the preparation of trans-zeatin (see Vol. 4 of these Reports) has been developed.A large number of 7-substituted theophylline derivatives (23a—i) have been synthesized by conventional steps as a result of observed pharmacological activity of this type of compound. For example, various 7-amino-... 

A tremendous upsurge in synthetic activity in this field is evident. A stereoselective synthesis of cis-zeatin (22), whose geometrical isomer was first isolated from Zea mays and shown to be a stimulant of cell division in plant tissue cultures, has been reported (Scheme 2). The Diels-Alder reaction of 1-chloro-l-nitro-socyclohexane (19) with isoprene gave the dihydro-l,2-oxazine hydrochloride (20) in moderate yield. Liberation of the base of (20) followed by zinc-acetic acid reduction gave the required amino-alcohol (21), which upon treatment with 6-chloropurine provided a separable mixture of cis-zeatin (22) and trans-zeatin. Standard tobacco callus bioassay for cytokinin activity showed that the natural trans-zeatin is at least 50 times more active than the synthetic cis-isomer (22). 

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