Naturalproductman’s Blog

Hey, is that a natural product?!

Archive for March, 2014

Power of enzymes

Posted by naturalproductman on March 30, 2014

Kenji Watanabe and co-workers at Shizuoka University have reported in Chembiochem on the formation of dimeric diketopiperazine alkaloids from a cytochrome P450.

 

Chembiochem paper

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

Posted by naturalproductman on March 28, 2014

Hideko Koshima and co-workers from Ehime University have reported in JOC on an asymmetric photocyclization of crystals to form chiral cyclobutenols using a chiral counterion.

photocyclization

JOC paper

Posted in Asymmetric, Crystal Structure, Methodology | Leave a Comment »

Cardamom peroxide synthesis

Posted by naturalproductman on March 27, 2014

Thomas Maimone and co-worker from UC Berkeley have reported in JACS on a 4-step synthesis of cardamom peroxide from myrtenal.

 

 

JACS paper

Posted in Diseases, Malaria, Peroxides, Total Synthesis | Leave a Comment »

(−)-Taxuyunnanine D synthesis

Posted by naturalproductman on March 19, 2014

Phil Baran and co-workers have published in JACS on the synthesis of taxayunnanine D.

taxadiene

JACS paper

Posted in Total Synthesis | Leave a Comment »

Halichondrin A synthesis

Posted by naturalproductman on March 19, 2014

Yoshito Kishi and co-workers published in JACS on the synthesis of halichondrin A.

halichondrin A

JACS paper

Posted in Total Synthesis | Leave a Comment »

Fumigatoside A

Posted by naturalproductman on March 17, 2014

Someone has brought to my attention the isolation of a recent alkaloid containing a strange alkynol attached to a nitrogen.

The main supporting evidence for this structure is the 3-bond HMBC correlation of the OH proton to the alkyne carbon taken in DMSO (the alcohol is at ~9.8 ppm).  The fishy thing here is that there is no 2-bond HMBC correlation (I assume it would be two bond from O-H and C-O) from the OH to the nearest alkyne carbon.

An interesting question would be how this alkynol would be introduced in the biological system. Alkynes are usually precursors to alkynols in P450 reactions and give rise to a rearrangement to form ketenes, which inactivate the enzymes.

Synthetically, I first saw alkynol structures from Sergey Kozmin’s work back in 2006. I should say that even here they are not alkynols – they are siloxy alkynes.

Perhaps anybody else has an opinion on this interesting structure?
alkynol

OL paper

Posted in Alkaloids, Biosynthesis | 2 Comments »

Kendomycin synthesis

Posted by naturalproductman on March 14, 2014

Hirokazu Arimoto and co-workers from Tohoku University have reported in ACIE on the synthesis of kendomycin.

kendomycin

ACIE paper

Posted in Methodology, Named Reactions, Palladium, Total Synthesis, Transition Metal, Tsuji-Trost | Leave a Comment »

Omaezallene

Posted by naturalproductman on March 14, 2014

Tatsufumi Okino and co-workers from Hokkaido University have reported in ACIE on the synthesis of omaezallene.

omaezallene

ACIE paper

Posted in Allenes, Asymmetric, Methodology, Total Synthesis | Leave a Comment »

Rubromycin synthesis

Posted by naturalproductman on March 14, 2014

Hans-Ulrich Leissig and co-workers at Freie Universitat Berlin have reported in ACIE on the synthesis of rubromycin.

rubromycin

ACIE paper

Posted in Methodology, Polyketides, Total Synthesis | Leave a Comment »

Mandelalide A synthesis

Posted by naturalproductman on March 14, 2014

Furstner and co-workers published in ACIE on the synthesis of mandelalide A, a macrolide found in South Africa. I wonder if this compound was named after Nelson Mandela.

mandelalide

ACIE paper

Posted in Macrolides, Methodology, Total Synthesis | 2 Comments »