Gibberellins. LXXXIII. Molecular and crystal structure of “Hydrogeno I”, a hydrogenolysis product of gibberellin A₃ methyl ester

Abstract

Gibberellins. LXXXIII. Molekül‐ und Kristallstruktur von „Hydrogeno I”︁, einem Hydrierprodukt von Gibberellin‐A3‐methylester Im Zusammenhang mit stereochemischen Untersuchungen an Gibberellinverbindungen wurde die Molekül‐ und Kristallstruktur von „Hydrogeno I”︁ 2, einem Produkt der katalytischen Hydrierung von Gibberellin‐A3‐methylester, durch Röntgenstrukturanalyse bestimmt. Verbindung 2 kristallisiert in der orthorhombischen Raumgruppe P212121 mit den Gitterkonstanten a = 10,316, b = 17,214 und c = 10,341 Å. Die Verfeinerung erfolgte bis zu einem R‐Wert von 0,074.

The chemistry of the gibberellins

“…An X-ray analysis of the hydrogenolysis acid, 'hydrogeno-1 ' (14), revealed that it retained a P-proton at C-9. 34 The products of relactonization of the hydrogenolysis acids possess the same C-5 and C-9 stereochemistry as the parent gibberellic acid. Oxidation of methyl gibberellate with manganese dioxide affords the ap-unsaturated ketone (24).…”

“…Methanol also adds across the double bond and in the presence of sodium methoxide a retro-Claisen reaction occurs with the formation of the adduct (33). 54 The stereochemistry of these adducts and their reduction products have been established by X-ray cry~tallography.~~ The addition of azide ion across the double bond to form the la-and Ip-azides (34) occurs56 readily and also provides a route to the l-hydroxygibberellins. Reduction of the 3-ketones gave the corresponding azido-alcohols which were photolysed to form the imines and thence the 1-ketones from which gibberellins A,, (35) and A,, (36) were prepared.…”

A 9,5-cyclogibberellin formed from a bromogibberellin-16-one derivative

“…None, however, exhibited a C9--C15 bond as observed in (2) and only two had a C1--C10 double bond: 2,7-dihydroxy-10-methoxycarbonyl-l-methyl-8-methylene-4/3-gibberell-4-ene-1-carboxylic acid (Kutschabsky, Reck, Adam, Argay & Czugler, 1981) and ent-3a, 13 -dihydroxy-7-methoxycarbonyl-20-norgibberella-l(10),16-diene-19-carboxylic acid (Kutschabsky, Adam & Voigt, 1987).…”