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A regio- and stereoselective approach to daunomycinone
Abstract
An efficient, stereoselective synthesis of an A-ring precursor, 269*, that is suitable for use in a synthesis of daunomycinone has been achieved in 9 steps and 18% overall yield starting with benzoic acid. The stereochemistry of the cis-1,3-diol was controlled by the axial addition of the acetyl equivalent, trimethylsilylethynyl cerium (III) chloride, to ketone 265a. The synthesis also incorporated a nitromethyl "umpolung" that can be converted to either a carbonyl in a route to daunomycinone or to a methylene in a synthesis of 6-desoxydaunomycinone. Previous model studies suggest that the "umpolung" will add to a DC precursor, juglone methyl ether monoacetal, to give an adduct which can cyclize to a tetracycle that could be elaborated to the anthracyclinones. A second stereoselective route to the A-ring precursor involving 6$\beta$-bromo-5$\beta$-hydroxy-2-cyclohexene-1$\beta$-carboxylic acid lactone was not successful. Lastly, two other regioselective approaches to the tetracyclic skeleton were investigated. It was determined that a photo Fries strategy from suitable naphthyl esters and an acylation route starting with 4-(ethylenedioxy)-5-methoxyl-1-oxo-1,2,3,4-tetrahydronaphthalene were not practical for the assembly of the tetracyclic framework. ftn*Please refer to dissertation for diagrams.
Subject Area
Organic chemistry
Recommended Citation
Svenningsen, Ralph E, "A regio- and stereoselective approach to daunomycinone" (1988). ETD collection for University of Nebraska-Lincoln. AAI9108248.
https://digitalcommons.unl.edu/dissertations/AAI9108248