Kauranes and Gibberellic Acids

Kauranes and Gibberellic Acids.— The parent tetracyclic diterpene from which the gibberellic acids are derived, is enf-kaurene (62). Several workers have 

The further metabolism of c r-kaurene (62) is consistent with a single pathway, involving the oxidation using oxygen gas to give 19-hydroxy-ent-kaur- 

16-ene, and thence via the 19-aldehyde to ent-kaur-16-en-19-oic acid. This acid is hydroxylated to give 7) -hydroxy-ent-kaur-16-en-19-oic acid which is the branch point to the kaurenolides (63) and gibberellic acids (64) and (68). Hydroxylation at the 6a-position gives the kaurenolide (63 R = H) which 

Gibbane aldehyde is converted into either gibberellic acid A12 (64) or A 4 

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