Naturalproductman’s Blog

Hey, is that a natural product?!

O-H Insertion

Posted by naturalproductman on December 8, 2009

Huw Davies and co-worker at Emory have recently reported in JACS on the use of an alpha,alpha-diazo-benzyl methyl ester to a chiral tertiary alcohol using a secondary alcohol and a asymmetric rhodium dimer catalyst.  The reaction involves an O-H insertion step followed by a [2,3]-sigmatropic rearrangement.  This chemistry reminds us how Michael Doyle’s methodology is very important in the field.

Cascade

JACS paper

Posted in Asymmetric, Cascade Reactions, Methodology, Transition Metal, X-H insertion | Leave a Comment »

Tandem Heterocyclization

Posted by naturalproductman on December 7, 2009

Junliang Zhang and co-workers from East China Normal University have recently published in Chemistry – A European Journal on a novel transformation that involves the coupling between an an alpha,beta-unsaturated imine and an enynone substrate.

tandem cyclization

Chemistry A European Journal Paper

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

C-C Cleavage Via Mesylate Displacement

Posted by naturalproductman on December 7, 2009

Johann Mulzer and co-workers at the University of Vienna have recently published in Chemistry – A European Journal on the lactone opening-decaboxylation via mesylate displacement to form homoallylic alcohols.

C-C cleavage

Chemistry – A European Journal paper

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

Cephalostatin Synthesis

Posted by naturalproductman on December 7, 2009

Matthew Shair and co-workers at Harvard have recently published in JACS on the synthesis of cephalostatin, which consists of two steroids in its backbone. The coupling of the two steroid fragments involved a pyrazine ring formation.

cephalostatin


JACS paper

Posted in Alkaloids, Steroids | Leave a Comment »

[6+4] for CP structures

Posted by naturalproductman on December 4, 2009

James Gleason and co-workers from McGill University in Canada have recently reported in Tetrahedron on a novel approach for the synthesis of CP molecules.  They used a cycloheptatrienone for a [6+4] reaction to form the bridged bicyclic component of the molecule.

6+4

Tetrahedron paper

Posted in Cycloaddition, Methodology | Leave a Comment »

Coprinastatin 1

Posted by naturalproductman on December 4, 2009

George Pettit and co-workers at Arizona State University have recently published in the Journal of Natural Products on the isolation of coprinastatin 1 that was found from a cap fungus, Coprinus cinereus, which was growing on a small plant found in Shasta-Trinity National Forest, CA. It had an ED50 value of 5.3 micrograms/mL towards P388 lymphocytic leukemia cells.

coprinastatin


JNP paper

Posted in Sesquiterpenes | Leave a Comment »

Gold-Catalyzed C-H/C-C Activation

Posted by naturalproductman on December 3, 2009

Yuxue Li and co-workers from the Shanghai Institute of Organic Chemistry have recently published in Org Lett on a cationic Au-catalyzed tandem C-H and C-C activation to convert vinyl cyclopropanes with saturated 6-membered rings to benzene rings.

C-H/C-C activation

OL paper

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

Reductive Coupling with Cobalt

Posted by naturalproductman on December 3, 2009

Chien-Hong Cheng and co-workers at the National Tsinghua University in Taiwan have recently published in JACS on this interesting reaction.  At quick first glance I was thinking that this reaction had released cyanide and was wondering how the person who ran this reaction would survive on a large scale. Then I took a closer look and realized that it’s not cyanide the product is missing it’s just a single nitrogen from the nitrile starting material that becomes dissociated.  What’s interesting is that when they used acetonitrile they would obtain the cyclized product but when they used benzonitrile, the product would be acyclic.

reductive coupling

JACS paper

Posted in C-X Bond Breaking, Cascade Reactions, Mechanistic, Methodology, Ring forming, Transition Metal | Leave a Comment »

Ru-Catalyzed C-H activation

Posted by naturalproductman on December 3, 2009

Sylvain Darses and co-workers at CNRS have recently published in JOC on the C-H activation of the beta-position of enone substrates by coupling with a vinyl silane.

C-H activation

JOC paper

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

Peloruside B

Posted by naturalproductman on December 3, 2009

Arun Ghosh and co-workers at Purdue University have recently reported in JOC on the biological activity and total synthesis of peloruside B in JOC.  They used a Yamaguchi macrolactonization to couple a carboxylic acid and a secondary alcohol to form the final macrolide structure.  Flow cytometry experiments were run to see the difference in the activities between the naturally isolated compound and the synthetically made one. The compound arrests cells in the G2M phase of the cell cycle.

peloruside B

JOC paper

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