15355-41-6Relevant articles and documents
Hydrolysis of Gibberellin 7-Methyl Esters: Anchimeric Assistance by a 15-Alcohol
Castellaro, Simon J.,MacMillan, Jake,Willis, Christine L.
, p. 2999 - 3004 (2007/10/02)
The neighbouring group effects of 15α- and 15β-hydroxy groups on the rate of hydrolysis of gibberellin 7-methyl esters are described.The presence of a 15-alcohol increases the rate of ester hydrolysis and a 15α- has a greater influence than a 15β-alcohol.The 15α-alcohol may be effective either through hydrogen bonding between the hydroxy proton and the ester carbonyl thus stabilising the tetrahedral intermediate formed on hydrolysis of the ester, or via 7,15α-lactonisation followed by hydrolysis of the lactone.The 15β-hydroxy may act through hydrogen bonding of a water molecule between the proton of the 15β-alcohol and the 7-carbonyl function.The effect is enhanced by the presence of a 13-acetate.
Preparation of Gibberellins A9 and A20 from Gibberellic Acid
Duri, Zvitendo J.,Fraga, Braulio M.,Hanson, James R.
, p. 161 - 164 (2007/10/02)
Methyl gibberellate has been converted via the methyl ester of 3-epigibberellin A1 into the 3β-chloro- and 3β,13-dichloro-derivatives using triphenylphosphine and carbon tetrachloride.Hydrogenolysis of the chlorides with tributyltin hydride afforded gibberellins A20 and A9 as their methyl esters.Gibberellin A9 methyl ester was also prepared from the gibberellin A4/A7 mixture.The stereochemistry of the conjugate reduction of the ring-A-unsaturated ketone is defined.
