scholarly journals Total Synthesis of LFA-1 Antagonist BIRT-377 via Organocatalytic Asymmetric Construction of a Quaternary Stereocenter.

ChemInform ◽  
2005 ◽  
Vol 36 (29) ◽  
Author(s):  
Naidu S. Chowdari ◽  
Carlos F. III Barbas
Keyword(s):  
Total Synthesis ◽  
Quaternary Stereocenter

A Concise Total Synthesis of (±)-Mesembrine

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1203-1206 ◽  
Author(s):  
Hyoungsu Kim ◽  
Hosam Choi ◽  
Kiyoun Lee
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Allylic Oxidation ◽  
Quaternary Stereocenter

A concise total synthesis of (±)-mesembrine has been successfully accomplished in seven steps and 24% overall yield from commercially available 3-ethoxy-2-cyclohexen-1-one. Central to the assembly of the skeleton of mesembrine are a Johnson–Claisen rearrangement for the formation of the benzylic quaternary stereocenter and direct allylic oxidation to generate the substrate for the amidation/transannular aza-conjugate addition reaction.

scholarly journals A Concise Total Synthesis of (±)-Vibralactone

2018 ◽  
Author(s):  
Sepand Nistanaki ◽  
Luke A. Boralsky ◽  
Roy D. Pan ◽  
Hosea Nelson
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Early Stage ◽  
Ring Expansion ◽  
Biologically Active ◽  
Valence Isomerization ◽  
Reduction Strategy ◽  
Quaternary Stereocenter

Disclosed is a four-step synthesis of (<i>±</i>)-vibralactone, a biologically active terpenoid natural product. A key photochemical valence isomerization of 3-prenyl-pyran-2-one forges both the all-carbon quaternary stereocenter and the β-lactone at an early stage. Cyclopropanation of the resulting bicyclic β-lactone furnishes a strained housane structure that is converted to the natural product through a sequential ring expansion and reduction strategy. Our concise and modular route to the natural product provides the shortest total synthesis of (<i>±</i>)-vibralactone reported to date. <br>

scholarly journals Asymmetric Total Synthesis of (+)-21-epi-Eburnamonine Via a Photocatalytic Radical Cascade Reaction

2020 ◽  
Author(s):  
Yuan Huang ◽  
Fanglin Xue ◽  
Hengmao Liu ◽  
Fei Xue ◽  
Xiao-Yu Liu ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Visible Light ◽  
Claisen Rearrangement ◽  
Cascade Reaction ◽  
Ring System ◽  
Asymmetric Total Synthesis ◽  
Radical Cascade ◽  
Key Features ◽  
Quaternary Stereocenter ◽  
Visible Light Photocatalytic

Abstract An asymmetric total synthesis of (+)-21-epi-eburnamonine has been achieved. Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system, and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter. Graphic Abstract

scholarly journals Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

2011 ◽  
Vol 7 ◽  
pp. 421-425 ◽  
Author(s):  
Silke Dubberke ◽  
Muhammad Abbas ◽  
Bernhard Westermann
Keyword(s):  
Total Synthesis ◽  
Building Block ◽  
Building Blocks ◽  
Allylic Rearrangement ◽  
Reaction Sequence ◽  
Enantiomerically Pure ◽  
Quaternary Stereocenter

Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the key step.

Total Synthesis and Structural Revision of a Harziane Diterpenoid

2019 ◽  
Author(s):  
Moritz Honig ◽  
Erick Carreira
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Spectral Characteristics ◽  
Tertiary Alcohol ◽  
Carbon Skeleton ◽  
Structural Revision ◽  
Stereochemical Analysis ◽  
Quaternary Stereocenter

The first total synthesis of nominal harziane diterpenoid is disclosed, whose spectral characteristics did not match those of the reported natural product. Stereochemical analysis and subsequent synthesis of the epimeric tertiary alcohol led to reassignment of configuration of the natural product. At the heart of the synthesis is an enyne cycloisomerization that sets a key quaternary stereocenter within a cyclobutane with high diastereocontrol. The route features strategies for the synthesis of the highly congested 6–5–7–4 carbon skeleton characteristic of the caged harziane diterpenoids.

scholarly journals Total Synthesis and Structural Revision of a Harziane Diterpenoid

2019 ◽  
Author(s):  
Moritz Honig ◽  
Erick Carreira
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Spectral Characteristics ◽  
Tertiary Alcohol ◽  
Carbon Skeleton ◽  
Structural Revision ◽  
Stereochemical Analysis ◽  
Quaternary Stereocenter

The first total synthesis of nominal harziane diterpenoid is disclosed, whose spectral characteristics did not match those of the reported natural product. Stereochemical analysis and subsequent synthesis of the epimeric tertiary alcohol led to reassignment of configuration of the natural product. At the heart of the synthesis is an enyne cycloisomerization that sets a key quaternary stereocenter within a cyclobutane with high diastereocontrol. The route features strategies for the synthesis of the highly congested 6–5–7–4 carbon skeleton characteristic of the caged harziane diterpenoids.

scholarly journals A Concise Total Synthesis of (±)-Vibralactone

2018 ◽  
Author(s):  
Sepand Nistanaki ◽  
Luke A. Boralsky ◽  
Roy D. Pan ◽  
Hosea Nelson
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Early Stage ◽  
Ring Expansion ◽  
Biologically Active ◽  
Valence Isomerization ◽  
Reduction Strategy ◽  
Quaternary Stereocenter

Disclosed is a four-step synthesis of (<i>±</i>)-vibralactone, a biologically active terpenoid natural product. A key photochemical valence isomerization of 3-prenyl-pyran-2-one forges both the all-carbon quaternary stereocenter and the β-lactone at an early stage. Cyclopropanation of the resulting bicyclic β-lactone furnishes a strained housane structure that is converted to the natural product through a sequential ring expansion and reduction strategy. Our concise and modular route to the natural product provides the shortest total synthesis of (<i>±</i>)-vibralactone reported to date. <br>

scholarly journals A Concise Total Synthesis of (±)-Vibralactone

2018 ◽  
Author(s):  
Sepand Nistanaki ◽  
Luke A. Boralsky ◽  
Roy D. Pan ◽  
Hosea Nelson
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Early Stage ◽  
Ring Expansion ◽  
Biologically Active ◽  
Valence Isomerization ◽  
Reduction Strategy ◽  
Quaternary Stereocenter

Disclosed is a four-step synthesis of (<i>±</i>)-vibralactone, a biologically active terpenoid natural product. A key photochemical valence isomerization of 3-prenyl-pyran-2-one forges both the all-carbon quaternary stereocenter and the β-lactone at an early stage. Cyclopropanation of the resulting bicyclic β-lactone furnishes a strained housane structure that is converted to the natural product through a sequential ring expansion and reduction strategy. Our concise and modular route to the natural product provides the shortest total synthesis of (<i>±</i>)-vibralactone reported to date. <br>

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