| 摘要 |
Processes for the preparation of 1,2-dihydro-3-hydroxy gibberellin acids of general formula (1) from precursor gibberellin acids that 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 acids; said processes comprising the reaction of either a 3-keto gibberellin of general formula (2), or of the general formula (3), or a mixture thereof, in the presence or absence of a proton source depending on the particular precursor gibberellin acid, with a compound of general formula (4): M+(alkyl)3BH-(4) wherein M30 represents a monovalent cation. - -<IMAGE> - -R1 R2 R3 R4 -(1) OH, H H, OH, alkoxy, H H - substituted alkoxy, - acyloxy -(2) O as above together, a - valence bond -(3) O as above H H -
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