Hirsutellone Synthesis

Nicolaou’s group has recently published in ACIEE on a cascade epoxide opening-Diels-Alder reaction to form the tricyclic ring system of hirsutellone B.

 

ACIEE paper

6-Pi Electrocyclization

Neil Branda and co-workers at Simon Fraser University reported on a 6-pi electrocyclization to activate a molecule that paralyzes a C. elegans worm.

 

JACS paper

Alkoxypalladation Cascade

Matthew Sigman and co-workers at the University of Utah have published on an alkoxypalladation followed by quinone methide formation and subsequent conjugate addition to form two contiguous centers enantioselectively.

 

JACS paper

Pleuromutilin Progress

Check out the radical cyclization cascade that led to the formation of two rings on pleuromutilin.

ACIEE paper

17-alpha-Estradiol

Recently Alan Pinkerton and co-workers at the University of Toledo did a study on the electronic properties of 17-alpha-estradiol, the unnatural form of estradiol where the 17-hydroxy group is pointing down.

 

JACS paper

Renieramycin M

Jieping Zhu and co-worker at CNRS have recently published in Organic Letters on the synthesis of Renieramycin M – a tetrahydroisoquinoline alkaloid with potent bioactivity.  They used aziridine subunits to introduce the nitrogen atoms in this molecule.

 

OL paper

Benzyne + Epoxide = ?

Kentaro Okuma and co-workers at Fukuoka University in Japan have recently published in Chemistry Letters on the reaction between a substituted expoxide, in-situ generated benzyne and chloroform to afford a regioisomeric mixture of products.  One of the fascinating parts of the proposed mechanism involves the nucleophilic attack of the epoxide oxygen onto the benzyne to form an oxonium intermediate that activates the epoxide as an electrophile.

Chemistry Letters paper

1,2-Amino Alcohol

Dingqiao Yang at South China Normal University has recently published in the Beilstein Journal of Organic Chemistry on an asymmetric Ir-catalyzed ring opening of an oxxabicyclic alkene using a tol-BINAP ligand.   The ee I must say was modest (50-81%) but it’s a promising start.

Beilstein Journal of Organic Chemistry link

Dehydrocoelenterazine

Green fluorescent proteins are 238-amino acid proteins that react three amino acids:  glycine, tyrosine and serine residues to make a fluorescent chromophore – in detail, the nitrogen of the amide between glycine and tyrosine attacks the carbonyl of the amide between tyrosine and serine to form a five membered ring.  Dehydration of the resultant hydroxy occurs followed by oxidation of the dihydroimidazolinone via oxygen to yield the chromophore, which has a conjugated pi system that extends all the way to the tyrosine side chain.  This protein is different from the protein found in bivalve molluscs that also emit light but in a different fashion.   Pholasin is the glycoprotein responsible for emitting light in the bivalve mollusc Pholas dactylus.  Masaki Kuse and co-workers at Nagoya University have identified the small molecule, a prosthetic group, that is responsible for helping the protein emit light.  The molecule, dehydrocoelenterazine (DCL), reacts with a thio group that in turn becomes oxidized and emits light.  If you compare the structure of DCL with the structure of the five membered ring in green fluorescent proteins, then you can see that the two structures are similar with an imidazolinone conjugated to a phenol ring.

ChemiBIOChem paper

GFP Science paper

Chivosazoles

Macrolides always seem to have highly potent bioactivities.  Florenz Sasse and co-workers from Abteilung Chemische Biologie, Helmholtz-Zentrum fur Infektionsforschung in Germany have recently revealed chivosazole’s nM IC50 antiproliferative activities.

ChemBioChem Paper