UBC Theses and Dissertations

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UBC Theses and Dissertations

Some aspects of natural products chemistry Yalpani, Mohamed


In part I of this thesis are described some studies toward the total synthesis of tetracycline. Attempts to transform the key aromatic compounds, terrarubein and 6-methylpretetramid into actual or hypothetical biosynthetic intermediates, failed to yield useful non-aromatic products. However, several of the transformations further along the route have been achieved. Thus, the conversion of 12a-deoxy-5a,6-anhydrotetracycline into 7-chloro-5a,6-anhydrotetracycline was successfully carried out. In a different approach it was attempted to convert the synthetic tetracycline derivative 7-chloro-4-dedimethylamino-5a,6-anhydrotetracycline to 7-chloro-5a,6-anhydrotetracycline via a series of bromination-aminatipn experiments. Chromatographic evidence is presented for the formation, in trace amounts, of 7-chloro-5a,6-anhydro-4-epi-tetracycline. Part II is concerned with the study of the possible precursor activity of triacetic acid lactone, a potential polyketomethylene chain intermediate in the biosynthesis of aromatic compounds. (3,5-¹⁴ C) Triacetic acid lactone was fed to P. patulum and labelled griseofulvin was isolated and degraded. It was found that radioactivity is incorporated into griseofulvin a non-specific way. In one strain of the mould used two new metabolites were found as a result of the addition of triacetic acid lactone. Addition of triacetic acid lactone to the mould also causes an unexplained enhancement of metabolite formation.

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