Synthesis gibberellin

The synthesis of the furan (176) and its conversion into the triester (177) as an intermediate in the synthesis of fujenoic acid have been described. " The metal-ammonia reduction of some polyfunctional tetrahydrofluorenes with the object of preparing intermediates for gibberellin synthesis has been noted. ... 

A total synthesis of ( )-royleanone from 5,7,8-trimethoxy-l-tetralone (123) has been described.129 The tetralone was converted into the tricyclic ketone (124), which was in turn converted into 11,12,14-trimethoxypodocarpatriene (125). Demethyla-tion and oxidation afforded the quinone (126 R = H) which was alkylated to give royleanone (126 R = Pr ). Synthetic studies in the resin acid series have led130 to the preparation of the dicarboxylic acid (127) with a cis a/b ring junction. The preparation of some tetracyclic ketones as intermediates for gibberellin synthesis has been described.131 132 The key reaction involves photolysis of a diazoketone (128) to afford the tetracyclic system (129). In a synthesis of phyllocladene from abietic acid... 

The 1,4-dihydrobenzoic acids derived from reductive alkylation may undergo facile rearomatization with either loss of the carboxylic acid group or the alkyl group. The gibberellin synthesis intermediate (82), for example, was found to be especially labile, forming (83) simply on exposure to air." Oxidative decarboxylation may be deliberately achieved with lead tetraacetate or electrochemically." Loss of the 1-alkyl group is likely to be a problem when the alkyl moiety can form a reasonably stable free radical, since a chain reaction may then be sustained." ... 

Several reports have appeared on the elaboration of other intermediates for gibberellin synthesis.178 179... 

MONNA, L., KITAZAWA, N., YOSHINO, R., SUZUKI, J., MASUDA, H., MAEHARA, Y., TANJl, M., SATO, M., NASU, S., MINOBE, Y., Positional cloning of rice semidwarfing gene, sd-1 rice "green revolution gene" encodes a mutant enzyme involved in gibberellin synthesis, DNA Res., 2002,9, 11-17. 

Genes involved in gibberellin synthesis and photosynthesis increase steadily in the developing embryos but not in the subtending callus ... 

Several triazole and pyrimidine ergosterol biosynthesis inhibitors (see section 5.4.5.5) also inhibit gibberellin synthesis, and therefore act as plant growth retardants, e.g. Paclobutrazol. 

---