The microbiological preparation of two ‘atisagibberellins’

2 pages, 3 schemes.-- Short report.Tetracyclic diterpenoids may be divided in terms of their ring C/D structure into the kaurene, 13β-kaurene (phyllocladene), atisene and beyerene (stachene) classes [1]. Although the naturally occurring gibberellins, which have hitherto been isolated, all belong to the ent-kaurene series, there is nothing known about gibberellin biosynthesis which would preclude the occurrence of gibberellin-like substances with other tetracyclic diterpenoid skeletons. The biosynthesis of the gibberellins in the fungus Gibberella fijikuroi utilizes ent-7α-hydroxykaur-16-en-19-oic acid (1) as a key intermediate (32% incorporation into gibberellic acid (2)) immediately prior to the contraction of ring B [2]. A number of kaurenoids differing from the normal metabolites have been transformed along part or the whole of this pathway depending upon their oxygenation pattern [3-6]. In this paper we record the preparation of the first ‘atisagibberellins’ using ent-7α-hydroxyatis-16-en-19-oic acid (3) [7] as an artificial substrate