Naturalproductman’s Blog

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Archive for November, 2009

CH-Pi Interactions

Posted by naturalproductman on November 30, 2009

I’ve heard of cation-pi interactions, which were popularized by people like Dennis Dougherty, but recently in JACS there’s a new theme: CH-Pi interactions. Karla Ramirez-Gualito and co-workers from the Universidad Autonoma Nacional de Mexico have recently published in JACS on this idea using nOes to identify which regions of a sugar molecule contaning acetyl and oxygen heteroatoms interact with the solvent of benzene.

CH-pi interactions
JACS paper

Posted in Methodology | Leave a Comment »

Palau’amide Synthesis

Posted by naturalproductman on November 29, 2009

Kiyotake Suenaga and co-workers from Keio University have recently published in Tetrahedron Letters on the synthesis of palau’amide, a cytotoxic depsipeptide that has an IC50 towards KB cells at 13 nM.

palau'amide

Tetrahedron Letters paper

Posted in Macrolides, Peptides | Leave a Comment »

Mycolactones toxic to Fish

Posted by naturalproductman on November 27, 2009

Kishi and co-workers at Harvard have recently reported in Chem Comm on the structure of a mycolactone from Mycobacterium marinum, which infects freshwater fish.

mycolactone

Chem Comm paper

Posted in Macrolides | Leave a Comment »

Asymmetric Heter-Diels-Alder Reaction

Posted by naturalproductman on November 27, 2009

Shunichi Hashimoto and co-workers from Hokkaido University have recently published in Chem Comm on an classic reaction – the Diels-Alder using Rawal’s diene and an aldehyde as the dienophile.  The reaction is also enantioselective.  They used a chiral rhodium dimer catalyst:  Rh2(S-BPTPI)4 (dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-piperidinonate]).

heterodielsalder

Chem Comm paper

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

Aldol that Didn’t Disturb the Diazo Group

Posted by naturalproductman on November 27, 2009

Xiaoming Feng and co-workers from Sichuan University have recently published in Chemical Communications on a Sc-catalyzed asymmetric Aldol reaction using a pyrrolidine-N-oxide or piperidine-N-oxide ligand.  Probably what stands out the most from the paper is that they used a alpha-diazoester as the nuclephile – something I would have expected to be reactive in the transformation.

alphadiazo aldol

 

Chem Comm paper

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

An Exciting Approach to Synthesize 5,5-Bicycles

Posted by naturalproductman on November 27, 2009

Gregory Fu and co-workers at MIT have recently published in ACIEE on the synthesis of diquinanes starting from an ynone-enoate substrate using a tri-n-butyl-phosphine catalyst. Looks like he based the reaction from Tomita’s work which was published in Organic Letters back in 2003 where Tomita had the same catalyst but instead used an alkyne-dione system.

phosphine
 

ACIEE paper

Tomita’s OL paper

**There’s a typo in the paper mis-spelling Tomita’s name in the first sentence.

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

Radical Cascade

Posted by naturalproductman on November 25, 2009

David Procter and co-workers at the University of Manchester have recently published in Tetrahedron on a radical cascade cyclization that involves a dialdehyde enoate substrate that forms four contiguous centers.

radical cascade

 

Tetrahedron paper

Posted in Cascade Reactions, Methodology, Radical Chemistry, Ring forming | Leave a Comment »

Transannular [4+3]

Posted by naturalproductman on November 24, 2009

Benjamin Gung and co-workers at the University of Miami in Ohio have recently published in the European Journal of Organic Chemistry on the synthesis of 6,7,6-tricyclic ring structures from a macrocycle using a gold catalyst.

transannular cycloaddition

 

European Journal of Organic Chemistry paper

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

Dihydropyran Cascade

Posted by naturalproductman on November 24, 2009

Cheng Ma and co-workers at Zhejiang University have recently reported in ACIEE on a cascade reaction that involves the use of a beta-bromo-alpha,beta-unsaturated enal and a beta,gamma-unsaturated alpha keto ester to form a spirocyclic center and an acetal.

cascade


ACIEE paper

Posted in Cascade Reactions, Conjugate Additions, Methodology, Organocatalytic, Ring forming | Leave a Comment »

Synthesis of Vinyl Fluorines

Posted by naturalproductman on November 24, 2009

Fluorine containing organic compounds are always interesting in terms of their biological activity.  Jinbo Hu and co-workers at the Shanghai Institute of Organic Chemistry have recently published in ACIEE where they used a nitrone and a sulfoximine to stereoselectively form the Z-olefin.  It’s similar to a Julia olefination but it’s more selective (100:0, Z:E selectivity was reported).

Vinyl Fluorines

ACIEE paper

Posted in Cascade Reactions, Methodology | Leave a Comment »

 
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