Abstract: Is the objective of the invention to develop a process for the production of tagged gibberellin-(7)-aldehydes which is of general applicability. As per the invention a gibberellin-(7)-aldehyde is converted into the gibberellin-(7)-aldehyde tagged at the C-15 position of the basic gibberellin skeleton under the influences of ultraviolet radiation, in given cases after the isolation of a developing 7-Hydroxy-7,15-cyclo butane derivative, and in the presence of compounds with tritium or deuterium donor properties respectively. The process is of particular suitability for the tagging of alkali-sensitive gibberellin-(7)-aldehydes. The tagged gibberellin-(7)-aldehydes produced by the process as per invention, are of importance for instance as primary materials for the obtaining of tagged natural gibberellins and their derivatives.

Abstract: As per invention, [6--.sup.3 H] or [6--.sup.2 H] gibberellins respectively are produced. By the process as per invention, production of tagged gibberellins is made from natural gibberellins or gibberellin derivatives having a carboxyl group at position 6 of the ent-gibberellin basic skeleton. After transformation into a gibberellin derivative with a hydroxymethyl group at position 6, oxidation is made to gibberellin-7-aldehyde with subsequent conversion of same to a mixture of 6-epimeric gibberellin-7-aldehydes, which will be obtained tagged at the C-6 position if deuterium or tritium donors are present during epimerization, oxidation into tagged gibberellins being performed thereafter.By the invention, tagged gibberellins are made available which are tritiated or deuterated to such a C-H bond as is present in unsubstituted state in all natural gibberellins and their derivatives, and at which bond no biochemical changes have hitherto been observed.