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Archive for August, 2009

Indole-3-Carbinol

Posted by naturalproductman on August 31, 2009

From the lab of Gary Firestone in UC Berkeley came a paper in PNAS in 2008 on the identification of I3C, indole-3-carbinol, that was shown to have anti-carcinogenic properties towards breast and prostate cancer cells.  What’s interesting about this molecule is that it’s found in many vegetables such as broccoli and brussell sprouts, so eat up on those greens folks.

PNAS paper

Posted in Aromatic | Leave a Comment »

Rh Catalyzed [5+2]

Posted by naturalproductman on August 31, 2009

Tamio Hayashi and co-workers at Kyoto University have recently published in Chemistry a European Journal on a [5+2] cyclization using a rhodium catalyst with a P-N ligand from an allylic cyclopropyl alkyne.

[5+2]

Chemistry a European Journal

Posted in Cascade Reactions, Cycloaddition, Methodology, Ring expansion, Ring forming, Seven-Membered Rings, Transition Metal | Leave a Comment »

Peroxy-Containing Anti-Malarials

Posted by naturalproductman on August 31, 2009

Giuseppe Campiani and co-workers from the University of Siena in Italy have recently  published in Tetrahedron Letters on a strategy for synthesizing cyclic peroxides.  These functional groups are important components found in many anti-malarial drugs.  They basically performed a regioselective hydroperoxysilylation using cobalt, oxygen atmosphere and triethylsilane onto an alkene.  This procedure was discovered originally by Isayama.  After forming the peroxide, they opened an epoxide to form the cyclic peroxide group.

cyclic peroxide

TL paper

Posted in Methodology, Peroxides, Ring forming, Ring Opening, Transition Metal | Leave a Comment »

Mg Catalyzed C-H Activation

Posted by naturalproductman on August 29, 2009

Daniel Seidel and co-workers at Rutgers have recently published in JACS on a C-H activation to form a new C-C bond through a magnesium catalyst.

JACS articleC-H Activation

Posted in Aromatic, C-H activation, Methodology, Ring forming | Leave a Comment »

Ipomoeassin Syntheses

Posted by naturalproductman on August 28, 2009

Furstner and co-workers at the Max Planck Institute in Germany have recently published in Chemistry A European Journal on the syntheses of Ipomoeassins A-F, which have nanomolar IC50s against OVCAR cancer cell lines.

ovcar ipomoeassins

Chemistry a European Journal paper

Posted in Glycosides | Leave a Comment »

Allene Formation

Posted by naturalproductman on August 26, 2009

It’s not a Grob fragmentation but as I was reading this JACS paper recently out by Lawrence Williams’ group from Rutgers, I saw some similarities.  He was able to access a cyclic allene compound using a enol triflate in conjugation with a TMS enol ether in the presence of TBAF.
allene

JACS paper

Posted in Allenes, C-C Bond Breaking, Cascade Reactions, Methodology, Ring expansion | Leave a Comment »

Phosphine Catalyzed [3+2]

Posted by naturalproductman on August 25, 2009

Zhengjie He and co-workers at Nankai University in China have recently published in Chemistry a European Journal on a phosphine catalyzed [3+2] using allenoates and aryl aldehydes to yield substituted tetrahydrofurans.  However, Ohyun Kwon’s group at UCLA has used similar substrates to form pyrones.

3+2

Chemistry a European Journal paper

Kwon’s OL paper

Posted in Allenes, Cascade Reactions, Cycloaddition, Methodology | Leave a Comment »

Enantioselective 2,3-Wittig Rearrangement

Posted by naturalproductman on August 25, 2009

Naoyoshi Maezaki and co-workers at Osaka Ohtani University in Japane have recently published in Chemistry a European Journal on an asymmetric 2,3-Wittig rearrangement using a bisoxazoline ligand and t-BuLi as the deprotonating base. There was no transition state proposed in this paper.

asymmetric wittig

Chemistry a European Journal paper

Posted in Asymmetric, Methodology, Sigmatropic Rearrangements | Leave a Comment »

Labeling Cancer Cells Using Chemistry

Posted by naturalproductman on August 21, 2009

Ralph Weissleder and co-workers at the Massachusetts General Hospital have recently published in ACIEE on a fascinating to visualize cancer cells.  Cetuximab antibodies containing cyclooctene moieties were used to bind the the EGFR (epidermal growth factor receptor) of A549 lung cancer cells.  These alkenes were then subjected to a Diels Alder reaction with a tetrazine unit that had a fluorophore attached.

label cancer cells

ACIEE paper

Posted in Cycloaddition, Methodology | Leave a Comment »

Au-Catalyzed [4+2]

Posted by naturalproductman on August 21, 2009

Jose Mascarenas et al at the Universidade de Santiago de Compostela in Madrid Spain have recently published a full paper in JACS on a Au-catalyzed intramolecular [4+2] cycloaddition of an allenyl diene.  It’s an interesting looking ligand.

JACS paper4+2

Posted in Cycloaddition, Methodology, Transition Metal | Leave a Comment »

 
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