Synthesis of Novel D-Secoestrone Isoquinuclidines by an Unpredicted Iminium Ion-Induced 1,5-Hydride Shift

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Abstract

Unique 9,13-bridged D-secoestrone alkaloids have been synthesized and structurally characterized. Treatment of 3-methoxy-16,17-secoestra-1,3,5(10)-trien-17-al (6a) with aniline (7) or substituted aniline derivatives 8-28 in the presence of different Lewis and Bronsted acids produces the bridged azaestrone derivatives 51-67 and the alkenes 68-73 in high yields in a domino-type process. The imines 29-50 are proposed as intermediates, undergoing 1,5-hydride shifts via the iminium ion salts 75 to give the cations 77, which, depending on the substitution pattern on the aniline moiety, either afford the bridged compounds through a nucleophihc addition of the formed secondary amine to the benzylic carbocation or give the alkenes through the abstraction of a proton at C-8.

Original languageEnglish
Pages (from-to)90-100
Number of pages11
JournalEuropean Journal of Organic Chemistry
Issue number1
Publication statusPublished - Jan 2004

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Hydrides
Alkenes
Ions
Bridged-Ring Compounds
Trientine
Derivatives
Lewis Acids
Imines
Alkaloids
Amines
Cations
Protons
Substitution reactions
Salts
aniline

Keywords

  • Benzylic carbon
  • Hydrides
  • Iminium salts
  • Lewis acids

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

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abstract = "Unique 9,13-bridged D-secoestrone alkaloids have been synthesized and structurally characterized. Treatment of 3-methoxy-16,17-secoestra-1,3,5(10)-trien-17-al (6a) with aniline (7) or substituted aniline derivatives 8-28 in the presence of different Lewis and Bronsted acids produces the bridged azaestrone derivatives 51-67 and the alkenes 68-73 in high yields in a domino-type process. The imines 29-50 are proposed as intermediates, undergoing 1,5-hydride shifts via the iminium ion salts 75 to give the cations 77, which, depending on the substitution pattern on the aniline moiety, either afford the bridged compounds through a nucleophihc addition of the formed secondary amine to the benzylic carbocation or give the alkenes through the abstraction of a proton at C-8.",
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T1 - Synthesis of Novel D-Secoestrone Isoquinuclidines by an Unpredicted Iminium Ion-Induced 1,5-Hydride Shift

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AU - Frank, E.

AU - Schneider, G.

AU - Tietze, Lutz F.

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N2 - Unique 9,13-bridged D-secoestrone alkaloids have been synthesized and structurally characterized. Treatment of 3-methoxy-16,17-secoestra-1,3,5(10)-trien-17-al (6a) with aniline (7) or substituted aniline derivatives 8-28 in the presence of different Lewis and Bronsted acids produces the bridged azaestrone derivatives 51-67 and the alkenes 68-73 in high yields in a domino-type process. The imines 29-50 are proposed as intermediates, undergoing 1,5-hydride shifts via the iminium ion salts 75 to give the cations 77, which, depending on the substitution pattern on the aniline moiety, either afford the bridged compounds through a nucleophihc addition of the formed secondary amine to the benzylic carbocation or give the alkenes through the abstraction of a proton at C-8.

AB - Unique 9,13-bridged D-secoestrone alkaloids have been synthesized and structurally characterized. Treatment of 3-methoxy-16,17-secoestra-1,3,5(10)-trien-17-al (6a) with aniline (7) or substituted aniline derivatives 8-28 in the presence of different Lewis and Bronsted acids produces the bridged azaestrone derivatives 51-67 and the alkenes 68-73 in high yields in a domino-type process. The imines 29-50 are proposed as intermediates, undergoing 1,5-hydride shifts via the iminium ion salts 75 to give the cations 77, which, depending on the substitution pattern on the aniline moiety, either afford the bridged compounds through a nucleophihc addition of the formed secondary amine to the benzylic carbocation or give the alkenes through the abstraction of a proton at C-8.

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