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Archive for November, 2010

Heptemerone G Synthesis

Posted by naturalproductman on November 29, 2010

Jerzy Wicha and co-workers at the Polish Academy of Sciences have published on a synthesis of hepemerone G by using Grubbs catalyst to form the seven membered ring.

guanacastepene

 

JOC paper

Posted in Cascade Reactions, Metathesis, Methodology, Ruthenium, Total Synthesis, Transition Metal | Leave a Comment »

Reveromycin A Synthesis

Posted by naturalproductman on November 28, 2010

Mark Rizzacasa and co-workers at the University of Melbourne have published in Synthesis on a total synthesis of reveromycin A via a hetero-Diels-Alder approach to access the spirocycle.

synthesis

Synthesis paper

Posted in Cascade Reactions, Cycloaddition, Diels-Alder, Methodology, Named Reactions, Pericyclic reactions, Polyketides, Total Synthesis | Leave a Comment »

Exocyclic Methylenes

Posted by naturalproductman on November 28, 2010

Tomasz Janecki and co-workers have published in Synlett on a nice way to make subsituted 3-methylidene-chroman-2-ones (ie:  exocyclic methylenes) via 1,4-Grignard addition folowed by Wittig.

exocyclic methylene

Synlett paper

Posted in Conjugate Additions, Horner-Wadsworth-Emmons, Methodology, Named Reagents | Leave a Comment »

Carbon Dioxide Activation

Posted by naturalproductman on November 27, 2010

Takashi Sakai and co-workers at Okayama University in Japan have published in Organic Letters on an organocatalytic reaction that embeds CO2 into epoxides.

CO2

 

OL paper

Posted in Cascade Reactions, Methodology, Organocatalytic | Leave a Comment »

Neojaponicone A

Posted by naturalproductman on November 26, 2010

Wei-Dong Zhang and co-workers from Shanghai Jiao Tong University have published in Chem Comm on the isolation of neojaponicone A, which had an IC50 value of 4.5 micrograms/mL activity against LPS-induced NO production in RAW264.7 macrophages.

neojaponicone A

Chem Comm paper

Posted in Sesquiterpenes, Seven-Membered Rings | Leave a Comment »

Friedel Crafts with Alkane as the Electrophile

Posted by naturalproductman on November 26, 2010

Yang Wang and co-workers from Fudan University have published on a very unusual Friedel-Crafts reaction where they used a regular alkane as the electrophilic unit.  You’re probably wondering how they did it…well all they did was put the alkyl substituted aromatic group in the presence of an alkene.  The alkene would generate a carbocation in the presence of either a Lewis acid (ie:  AlCl3) or Bronstead acid (triflic acid) and that carbocation would in turn strip off a hydride from the Friedel-Crafts substrate (from the alkyl substituent of the aromatic ring).

FC reaction

Europea JOC paper

Posted in Cascade Reactions, Friedel-Crafts, Methodology, Named Reactions | Leave a Comment »

Torrubiellone A

Posted by naturalproductman on November 24, 2010

Masahiko Isaka and co-workers from BIOTEC in Thailand have published in the Journal of Natural Products on the isolation of torrubiellone A, which had anti-malarial activity with an IC50 of 8.1 micromolar.

torrubiellone

 

JNP paper

Posted in Alkaloids, Diseases, Malaria | Leave a Comment »

Homo-Nazarov using Indium

Posted by naturalproductman on November 24, 2010

Stefan France and co-workers at Georgia Institute of Technology have published in Organic Letters on an indium catalyzed homo-Nazarov reaction using a cyclopropyl-vinyl-ketone as the substrate. As a result a six membered ring is formed.

cyclopropyl

 

OL paper

Posted in Electrocyclization, Methodology, Named Reactions, Nazarov cyclization, Pericyclic reactions | Leave a Comment »

Duboscic acid

Posted by naturalproductman on November 22, 2010

Pascal Wafo and co-workers from France have published in Organic Letters on the isolation of duboscic acid.  It had alpha-glucosidase inhibition activity with with an IC50 value of 100 ± 8.1 μM.  So you might wonder why alpha-glucosidase inhibition is important – alpha-glucosidase is an enzyme that hydrolyzes disaccharides into monosaccharides so the inhibition of this enzyme should slow down the absorption of glucose in people, which is especially important in diabetic patients.

triterpenoid

 

OL paper

Posted in Diabetes Type 2, Diseases, Seven-Membered Rings, Triterpenoids | Leave a Comment »

Sn2 Prime Followed by SE2 Prime

Posted by naturalproductman on November 19, 2010

Tamotsu Takahashi and co-workers at Hokkaido University have published in Organic Letters on a palladium catalyzed Sn2 prime reaction followed by a desilylative SE2 prime reaction.

sn2 prime

 

OL paper

Posted in Asymmetric, Cascade Reactions, Methodology, Palladium, Sn2 prime, Transition Metal | Leave a Comment »

 
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