Naturalproductman’s Blog

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Archive for the ‘Metathesis’ Category

Penostatin B synthesis

Posted by naturalproductman on December 9, 2011

Kozo Shishido and co-workers at the University of Tokushima have reported in Organic Letters on the synthesis of penostatin B relying on a relay ring closing metathesis.

penostatin

OL paper

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Posted in Asymmetric, Cascade Reactions, Metathesis, Methodology, Named Reactions, Pauson-Khand, Total Synthesis | Leave a Comment »

Africanan-1alpha-ol synthesis

Posted by naturalproductman on November 11, 2011

Douglass Taber and co-workers from the University of Delaware have reported in JOC on the synthesis of trans-africanan-1alpha-ol. The synthesis of the seven membered ring was achieved from a relay-ring closing metathesis reaction.  The synthesized structure does not seem to match the reported structure.

seven

JOC paper

Posted in Asthma, Cascade Reactions, Diseases, Metathesis, Methodology, Ruthenium, Sesquiterpenes, Seven-Membered Rings, Structural Reassignment, Total Synthesis, Transition Metal | Leave a Comment »

Z-selective RCM with tungsten

Posted by naturalproductman on November 4, 2011

Amir Hoveyda and co-workers from Boston College have reported in Nature on a ring closing metathesis approach to access macrocyclic natural products with a Z-olefin using a tungsten alkylidene.

 

Nature paper

Posted in Metathesis, Methodology, Ring forming, Total Synthesis, Transition Metal, Tungsten | Leave a Comment »

Tulearin C synthesis

Posted by naturalproductman on October 11, 2011

Alois Furstner and co-workers have reported in ACIEE on their synthesis of tulearin C.  They exploited an alkyne metathesis followed by a trans reduction to form the macrocycle.

tulearin

ACIEE paper

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

Ophiobolin synthesis

Posted by naturalproductman on September 15, 2011

Masahisa Nakada and co-workers have reported in ACIEE on a synthesis of ophiobolin where the seven membered ring was accessed via a ring closing metathesis.

ophiobolin

ACIEE paper

Posted in Cancer, Cascade Reactions, melanoma, Metathesis, Methodology, Named Reactions, Reformatsky, Ring forming, Ruthenium, Sesquiterpenoids, Seven-Membered Rings, Transition Metal | Leave a Comment »

Ring rearrangement metathesis

Posted by naturalproductman on August 29, 2011

Nicolas Blanchard and co-workers at Universite de Haute-Alsace in France have reported in Chem Comm on  a spiroketalization via a ring rearrangement metathesis – add that to your new lexicon.

metathesis

Chem Comm paper

Posted in Cascade Reactions, Metathesis, Methodology, Ring forming, Ring Opening, Ruthenium, Spirocyclic centers, Spiroketals, Transition Metal | Leave a Comment »

Nakadomarin A synthesis

Posted by naturalproductman on August 8, 2011

Darren Dixon and co-workers at the University of Oxford have reported in Chem Comm on their synthesis of nakadomarin A.  That Z-alkene in the macrocycle has been a problem in the past (cf:  Kerr’s synthesis) but here they have resolved the issue by a syn-reduction of an alkyne, which was obtained from an alkyne ring closing metathesis reaction.

nakadomarin A

Chem Comm paper

Posted in Alkaloids, Asymmetric, Metathesis, Methodology | Leave a Comment »

E alkene from E/Z-mixture

Posted by naturalproductman on July 7, 2011

Ever want to selectively isolate the E-isomer of a E/Z-mixture of alkenes?  Well Hoveyda and Schrock have reported in JACS on the use of a molybdenum catalyst (monoaryloxide-pyrrolide – ie:  MAP – complex with molybdenum) in the presence of ethylene to completely abolish the Z-alkene from the mixture via ethenolysis.

molybdenum

JACS paper

Posted in Carbene, Cascade Reactions, Kinetic resolution, Metathesis, Methodology, Molybdenum, Transition Metal | Leave a Comment »

Radical chemistry approach to epimeloscine

Posted by naturalproductman on June 17, 2011

Dennis Curran and colleague have reported in JACS on their syntheses of epimeloscine and meloscine.

radical
JACS paper

Posted in Alkaloids, Cascade Reactions, Metathesis, Methodology, Radical Chemistry | Leave a Comment »

Z-selective Olefin Metathesis

Posted by naturalproductman on May 13, 2011

The challenge of olefin cross metathesis was always getting selectivity of Z vs. E olefins.  Grubbs and colleague have reported in JACS on a ruthenium catalyst with a chelating ligand to select for Z-alkenes.

chelated

JACS paper

Posted in Carbene, Metathesis, Methodology, Ruthenium, Transition Metal | Leave a Comment »