Cycloaddition-fragmentation mediated pathways to ring D modified 19-norsteroids

 

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dc.contributor.advisor Bull, James R en_ZA
dc.contributor.author Sickle, Eugene Stanford en_ZA
dc.date.accessioned 2016-03-17T12:46:07Z
dc.date.available 2016-03-17T12:46:07Z
dc.date.issued 1997 en_ZA
dc.identifier.citation Sickle, E. 1997. Cycloaddition-fragmentation mediated pathways to ring D modified 19-norsteroids. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17967
dc.description Includes summary. en_ZA
dc.description Includes bibliographical references. en_ZA
dc.description.abstract An efficient strategy for the synthesis of 14β-3'-oxobutyl 19-norsteroids has been developed and the intramolecular reactivity of the derived compounds has been investigated. The approach is based on cycloaddition of methyl vinyl ketone to 3-methoxyestra-1,3,5(10),14,16-pentaen-17-yl acetate which proceeded with a high degree of regio- and stereoselectivity to give 16α-acetyl-3-methoxy-14, 17α-ethenoestra-1 ,3,5(1 O)-trien-17β-yl acetate. The cycloadduct underwent base mediated fragmentation, affording an efficient and stereocontrolled synthesis of 3-methoxy-14β-3'-oxobutylestra-1,3,5(10),15-tetraen-17-one which in turn gave 3-methoxy-5',6'-dihydro-15αH-benzo[14,15]-14β-estra-1,3,5(1O)-trien-4'(3'H), 17-dione via an intramolecular Michael reaction. Regioselective deoxygenation of the dione at C-4', followed by standard functional group modifications provided the parent 14β-perhydrobenzo[14,15]-estradiol analogues. An alternative, more expedient, route to this novel steroidal ring system was developed which relied on an anionic oxy-Cope rearrangement as the key step. Thus methylenation of the cycloadducts derived from reaction of the dienyl acetate and selected dienophiles (acrolein and methyl vinyl ketone) gave after hydrolysis of the bridgehead ester, substrates which underwent [3,3]sigmatropic rearrangement to generate a series of 14β-perhydrobenzo[14,15]-17-ketones. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Chemistry en_ZA
dc.title Cycloaddition-fragmentation mediated pathways to ring D modified 19-norsteroids en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Chemistry en_ZA
dc.type.qualificationlevel Doctoral en_ZA
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image


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