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Archive for the ‘Umpolung’ Category

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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 »

Making Enones

Posted by naturalproductman on April 12, 2010

The benzoin condensation takes advantage of umpolung chemistry where the aldehyde, which is normally an electrophile, is used as a nucleophile.  Frank Glorius and co-workers from Organisch-Chemisches Institut der Westfalischen Wilhelms-Universitat Munster have made use of this umpolung reactivity and used an alkyne as the reactant with the aldehyde.

aldehyde
JACS paper

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

Umpolung Reaction

Posted by naturalproductman on June 15, 2009

Talk about some new umpulong chemistry – John Verkade at Iowa State University has recently published in Tetrahedron Letters on a reaction that coupled a 1,3-dithiane moiety to an electrophile, which was in this case, an aldehyde.  The 1,3-dithiane was equipped with a TMS group in the 2 position and the catalyst that was used was a phosphino-amino-catalyst or a proazaphosphatrane catalyst. It’s a good complement to the N-heterocyclic carbene reactions that people such as Bode and Rovis like to use.

umpolung

TL paper

There is a recent JOC paper from the same authors that changed the starting material to an alpha-TMS-nitrile and can add to the scope of this reaction:

JOC link

Posted in Methodology, Organocatalytic, Umpolung | Leave a Comment »

Cascade Metathesis

Posted by naturalproductman on May 28, 2009

Paul Hanson at the University of Kansas came out with a nice paper on cascade metathesis reactions.

cascade metathesis

Tetrahedron paper

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

Salinosporamide A

Posted by naturalproductman on May 28, 2009

Jeff Bode’s group at UPenn has come up with a new way to make salinosporamide using his carbene reaction. The intramolecular NHC reaction is a nice way to make the lactam framework of the molecule. You can check the paper out in Tetrahedron.

NHC reaction

Tetrahedron paper

Posted in Alkaloids, Carbene, Methodology, Ring forming, Umpolung | Leave a Comment »

Carbene Catalysis

Posted by naturalproductman on May 26, 2009

Jeffrey Bode at University of Pennsylvania has come up with a JACS paper that is based on his carbene methodology to make new carbon carbon bonds.

carbene

JACS link

Posted in Methodology, Organocatalytic, Ring forming, Umpolung | Leave a Comment »

 
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