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dc.creatorBjelaković, Mira
dc.creatorLorenc, Ljubinka
dc.creatorPavlović, Vladimir D.
dc.creatorTinant, Bernard
dc.creatorDeclercq, Jean-Paul
dc.creatorKalvoda, Jaroslav
dc.date.accessioned2021-02-02T06:55:12Z
dc.date.available2021-02-02T06:55:12Z
dc.date.issued2003
dc.identifier.issn0018019X
dc.identifier.issn15222675
dc.identifier.urihttps://cer.ihtm.bg.ac.rs/handle/123456789/4187
dc.description.abstractOxidations of 5α‐hydroxy‐B‐norcholestan‐3β‐yl acetate (8) with Pb(OAc)4 under thermal or photolytic conditions or in the presence of iodine afforded only complex mixtures of compounds. However, the HgO/I2 version of the hypoiodite reaction gave as the primary products the stereoisomeric (Z)‐ and (E)‐1(10)‐unsaturated 5,10‐seco B‐nor‐derivatives 10 and 11, and the stereoisomeric (5R,10R)‐ and (5S,10S)‐acetals 14 and 15 (Scheme 4). Further reaction of these compounds under conditions of their formation afforded, in addition, the A‐nor 1,5‐cyclization products 13 and 16 (from 10) and 12 (from 11) (see also Scheme 6) and the 6‐iodo‐5,6‐secolactones 17 and 19 (from 14 and 15, resp.) and 4‐iodo‐4,5‐secolactone 18 (from 15) (see also Scheme 7). Oxidations of 5β‐hydroxy‐B‐norcholestan‐3β‐yl acetate (9) with both hypoiodite‐forming reagents (Pb(OAc)4/I2 and HgO/I2) proceeded similarly to the HgO/I2 reaction of the corresponding 5α‐hydroxy analogue 8. Photolytic Pb(OAc)4 oxidation of 9 afforded, in addition to the (Z)‐ and (E)‐5,10‐seco 1(10)‐unsaturated ketones 10 and 11, their isomeric 5,10‐seco 10(19)‐unsaturated ketone 22, the acetal 5‐acetate 21, and 5β,19‐epoxy derivative 23 (Scheme 9). Exceptionally, in the thermal Pb(OAc)4 oxidation of 9, the 5,10‐seco ketones 10, 11, and 22 were not formed, the only reaction being the stereoselective formation of the 5,10‐ethers with the β‐oriented epoxy bridge, i.e. the (10R)‐enol ether 20 and (5S,10R)‐acetal 5‐acetate 21 (Scheme 8). Possible mechanistic interpretations of the above transformations are discussed.
dc.publisherWiley
dc.rightsrestrictedAccess
dc.sourceHelvetica Chimica Acta
dc.subjectOxidation
dc.subjectLead-tetracetate
dc.subjectSteroids
dc.subjectFragmentation
dc.subjectIsomers
dc.subjectPb(OAc)4
dc.subjectConformation
dc.titleOxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates
dc.typearticle
dc.rights.licenseARR
dcterms.abstractТинант, Бернард; Калвода, Јарослав; Павловић, Владимир Д.; Децлерцq, Јеан-Паул; Бјелаковић, Мира; Лоренц, Љубинка;
dc.citation.volume86
dc.citation.issue6
dc.citation.spage2121
dc.citation.epage2135
dc.identifier.doi10.1002/hlca.200390169
dc.identifier.scopus2-s2.0-0041804056
dc.type.versionpublishedVersion


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