Naturalproductman’s Blog

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Archive for June, 2010

New Way to Make Amide Bonds

Posted by naturalproductman on June 30, 2010

Jeffrey Johnston and co-workers at Vanderbilt University have published in Nature on a new way to make amide bonds by reacting a bromo-nitro compound and an amine group in the presence of NIS.

NIS

Nature paper

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

Intramolecular C-H Activation with Palladium

Posted by naturalproductman on June 30, 2010

Jing-Hua Li and co-workers at Zhejiang University of Technology have published in Synthesis on a palladium/copper coupled intramolecular C-H activation to synthesize an indole ring.  The way they made the C-H activation precursor (enamine) was by grinding cyclohexan-1,3-dione and aniline together – something you don’t usually see in a typical procedure…

C-H


Synthesis

Posted in C-H activation, Cascade Reactions, Methodology, Palladium, Transition Metal | Leave a Comment »

Asymmetric Oxidative Coupling with Cu(OTf)2

Posted by naturalproductman on June 30, 2010

Liu-Zhu Gong and co-workers at the University of Science and Technology in China have published in ACIEE on a copper triflate catalyzed C-H activation reaction that uses DDQ as the stoichiometric oxidant.  The reaction couples a benzyl position and a malonate group to enantioselectively build a new carbon center.

C-H activation

ACIEE paper

Posted in Asymmetric, C-H activation, Copper, Methodology, Transition Metal | Leave a Comment »

Claisen Rearrangement to Access Chiral Quaternary Carbons

Posted by naturalproductman on June 30, 2010

Derrick Clive and co-worker at the University of Alberta have published in JOC on Claisen rearrangement approach to access a chiral quaternary carbon center.  The stereoselectivity comes from substrate control where the chiral center originates from serine.  The dihydropyran Claisen rearrangement precursor is synthesized from an intramolecular Michael addition of an amine to an alkynone.  The presumed vinyl ether is not isolated as they react an alcohol with butyl vinyl ether in the presence of Hg(OAc)2 to spontaneously undergo the Claisen rearrangement.

claisen

JOC paper

Posted in Cascade Reactions, Claisen rearrangement, Diastereoselective, Methodology, Named Reactions, Pericyclic reactions, Sigmatropic Rearrangements | Leave a Comment »

Anthopogochromane

Posted by naturalproductman on June 30, 2010

Anthopogochromane A, a tetracyclic compound isolated from the Chinese medicinal plant Rhododendron anthopogonoides, was found to have anti-inflammatory activities.  The tetracyclic compound, anthopogochromane A,  had an IC50 of 114 micromolar while the bicyclic compound, anthopogochromane B, had an IC50 value of 63 micromolar.  The anti-inflammatory activity was calculated by measuring the histamine released upon addition of histamine releasers (compound 48/80).

anthopogochromane


JNP paper

Posted in Aromatic, Polyketides | Leave a Comment »

Indanone Synthesis by Kicking out Thiophene

Posted by naturalproductman on June 30, 2010

Nicolai Cramer and co-workers at ETH Zurich have published in Synlett on a rhodium catalyzed indanone synthesis that involves breaking open a cyclobutanol and kicking off a thiophene group to give rise to a highly enantioselective reaction.

cyclobutanol

Synlett paper

Posted in C-C Bond Breaking, C-H activation, Cascade Reactions, Methodology, Rhodium, Ring Opening, Transition Metal | Leave a Comment »

Carbonyl Ylide Approach to Seven Membered Rings

Posted by naturalproductman on June 29, 2010

Martin Maier and co-workers at the Universitat Tubingen have published in Organic Letters on a carbonyl ylide cycloaddition with allyl propiolate to synthesize a guaianolide 5,7-bicyclic ring system.

Carbonyl Ylide

OL paper

Posted in Cascade Reactions, Cycloaddition, Methodology, Pericyclic reactions, Rhodium, Transition Metal, Ylides | Leave a Comment »

Cope Rearrangement to Seven Membered Rings

Posted by naturalproductman on June 29, 2010

Seven membered rings are hard to make but Vladimir Birman and co-workers at Washington University have published in Organic Letters on a [3,3] Cope rearrangement approach to access seven membered rings.

seven

OL paper

Posted in Cascade Reactions, Cope rearrangement, Methodology, Named Reactions, Pericyclic reactions, Ring forming, Sigmatropic Rearrangements | Leave a Comment »

Ruthenium Catalyzed Isotopic Labeling

Posted by naturalproductman on June 29, 2010

Hironao Sajiki and co-workers at Gifu Pharmaceutical University have published in Chem Comm on a ruthenium on carbon method to exchange protons with deuterium on a sugar in the presence of hydrogen gas and D2O.  You probably can’t have any alkenes in your molecule since they might get hydrogenated.
deuteration

Chem Comm paper

Posted in C-H activation, Methodology, Ruthenium, Transition Metal | Leave a Comment »

Iridacycles

Posted by naturalproductman on June 28, 2010

Yasushi Tsuji and co-workers at Kyoto University have published in JACS on the synthesis of 2-quinolones from alkynes and N-arylcarbamoyl chlorides using an iridium catalyst.

iridacycle

JACS paper

Posted in Cascade Reactions, Iridium, Methodology, Ring forming, Transition Metal | Leave a Comment »

 
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