| 摘要 |
The invention provides a process for the preparation of 1,2-dihydro-2-hydroxy gibberellin acids of the general formula (10):
<CHEM>
therein R<2> is H, OH, alkoxy, substituted alkoxy or acyloxy, and R<3> and R<4>, are each H or alkyl, from precursor gibberellin acids of formula (11):
<CHEM>
and/or formula 13
<CHEM>
by reaction with a compound of general formula (12)
M<-> (R<6>)3 BH<-> 12
wherein M<-> represents a monovalent cation and R<6> represents an alkyl group, in the presence of a proton source when a compound of formula (11) is used. This process employs conditions which (a) do not require prior protection of the free carboxylic acid group; (b) preserve the DELTA (16)-olefinic bond and the lactone; and (c) enable the stereochemistry of the hydroxyl moiety at position 3 to be controlled, enabling access to the individual stereoisomers of the 1,2-dihydro-3-hydroxy gibberellin acid. |
