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Archive for February, 2009

Palau’amine

Posted by naturalproductman on February 27, 2009

Palau’amine, isolated by the group of the late Paul Scheuer in the University of Hawaii at Manoa in 1993, is still a desirable target for synthetic chemists around the world.  Many people are working on it and it has yet to be synthesized by anybody.  The stereochemistry of the cyclopentane core is controversial.  It is an oroidin dimer natural product just like massadine, however, massadine has been synthesized by the Baran group at Scripps last year.

JACS isolation

Posted in Alkaloids, Trophy Targets | Leave a Comment »

TTN Ring Contraction

Posted by naturalproductman on February 27, 2009

The ring contraction reaction is a pretty neat trick using a thallium reagent published by University of Basel in Switzerland and University of Sao Paulo in Brazil by Andreas Pfaltz and Luiz Silva and co-workers in JOC.

ttn-reaction


JOC paper

A review on ring contractions by Silva can be found in TL:
TL Review
ring contraction

Posted in New Types, Sesquiterpenes | Leave a Comment »

Cribrostatin 6 Synthesis

Posted by naturalproductman on February 26, 2009

Stephen Martin (no not the actor) at the University of Texas at Austin published a paper in ACIEE on the synthesis of cribrostatin 6. The way he made the substituted aromatic ring is really cool.

cribrostatin

ACIEE paper

Posted in Alkaloids | Leave a Comment »

A New Tetrahydrofuranyl Synthesis

Posted by naturalproductman on February 26, 2009

Tristan Lambert at Columbia University has come up with yet another clever methodology. Using Bismuth as the catalyst, he starts with an enal and reacts with a nucleophile. The nucleophile attacks the aldehyde and a hydroalkoxylation follows. It’s a very neat and simple looking protocol.

Lambert's hydroalkoxylation reaction

Org. Lett.

Posted in Methodology | Leave a Comment »

Synthesis of (+)-Serratezamine A

Posted by naturalproductman on February 24, 2009

Jeffrey Johnston’s group at Vanderbilt University has come up with a synthesis of serratezamine, an alkaloid with an interesting polycyclic backbone.

serratezamine


JACS paper

Posted in Alkaloids | Leave a Comment »

Synthesis of Norfluorocurarine

Posted by naturalproductman on February 24, 2009

Chris Vanderwal from UC Irvine has published in JACS a synthesis of norfluorocurarine, an alkaloid with a very interesting polycyclic skeleton.

norfluorocurarine

JACS paper

Posted in Alkaloids | Leave a Comment »

A New Way to Make Benzopyrans

Posted by naturalproductman on February 24, 2009

Dean Toste at the University of California at Berkeley has recently published in JACS – you guessed it:  more gold chemistry.  This reaction takes advantage of allylic oxonium intermediates to form the new ring.  It’s certainly a puzzle to figure out this mechanism.

gold reaction

The JACS paper

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

Protonation of Vinyl Ethers for Aldol Reactions

Posted by naturalproductman on February 23, 2009

Here’s a novel idea – using a chiral bronstead acid catalyst to promote a direct aldol reaction. Masahiro Terada at Tohoku University has recently published in JACS on this new reaction.

bronstead acid aldol


JACS paper

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

New Manzamine Alkaloids from Sponge Amphimedon sp.

Posted by naturalproductman on February 21, 2009

Tetrahedron has some nice papers and Jun’ichi Kobayashi from Hokkaido University is one of the fine contributors to this journal.  He and his group has just recently published an isolation of some novel alkaloid structures that makes you think of nakadomarin and the like.  Zamamidine C, 3,4-dihydro-6-hydroxy-10,11-epoxymanzamine A,  and 3,4-dihydromanzamine J N-oxide are three new structures isolated from a sponge. Zamamidine had microgram/mL activity against Trypanosoma brucei, the protist that is the cause of African sleeping sickness (transmitted by the tse tse fly).

zamamidine C

 

The TL paper

Posted in Alkaloids | Leave a Comment »

[2+2+2] Cycloaddition Strategy Catalyzed by Rh to Synthesize an Indolizidine Alkaloid

Posted by naturalproductman on February 20, 2009

Tomislav Rovis from Colorado State has a really neat reaction out in ACIEE.  Figuring out the mechanism would be a cool thing to do – it’s not straight forward.

[2+2+2]

ACIEE paper

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

 
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