Nitrone-Ketene Coupling

Andrew Smith and co-workers at the University of St. Andrews in the UK have recently published in Organic Letters where they have reported on a reaction cascade that involves a nucleophilic addition of the nitrone onto the ketene followed by a 3,3-sigmatropic rearrangement to eventually form an oxindole.  The reaction takes place in a dry ice bath temperature and the ketene is formed in-situ from an acid chloride with triethylamine.

OL paper

Neodymium Chemistry

Min Shi and co-worker from the Shanghai Institute of Organic Chemistry have recently published in the European Journal of Organic Chemistry on an intermolecular coupling reaction between an allenyl cyclopropane and an enynol using a Nd catalyst.  It results in the formation of a 5,7,6-fused tricycle that shares the carbon cyclic backbone with a famous antibiotic, guanacastapene.

European Journal of Organic Chemistry

The Novelty of an Olefin Metathesis Reaction

Subrata Ghosh and co-workers at the Indian Association for the Cultivation of Science have recently published their progress toward a natural product, Caribenol A in Tetrahedron Letters.  It’s a very interesting entry to making 5,7-bicyclic rings.  I know that olefin metathesis is becoming very common and not as exciting and novel but the olefin metathesis they did in this case involved the opening of the norbornene derivative that gave rise to the five membered ring.

TL paper

Platensimycin Studies

Sheo Singh and co-workers at Merck have recently published in Tetrahedron Letters on the interaction of platensimycin with the enzyme FabF, an enzyme found in the fatty acid biosynthetic pathway.  Inhibition of these classes of enzymes leads to the compound’s antibiotic activity.  They even have a co-crystal structure reported in the paper between the molecule and the enzyme.

Nature paper

TL paper

Four Component Reaction

Shu-Jiang Tu (Xuzhou Normal University and Suzhou University) and coworkers in collaboration with Guigen Lee (Texas Tech) and co-workers have recently published in JACS on a four component reaction that involves the combining of an aldehyde, ketone and two cyanoamides to form tricyclic 5,6,6-rings that look like alkaloid type molecules. It’s a simple protocol that requires microwave heating at 120 degrees celsius for 12 min in the presence of 1 equivalent of potassium carbonate.

JACS article

A Five Component Reaction

Carlos Marcos et al at the Universidad de Extremadura have recently published on a five component coupling reaction in JOC.  Well, basically it’s an Ugi followed by condensation with an amine to form a spiropyrrolidinochromanone.  Ugi reactions normally consist of an aldehyde or ketone, isocyanide, amine and carboxylic acid.  The special type of Ugi reaction we see here has an aldehyde with extra functionality – a chromone moiety.

JOC paper

Uncialamycin Progress

Nicolau has already synthesized uncialamycin.  However, just because one person has completed the synthesis, it doesn’t mean there will be more elegant ways to access the same target molecule.  This enediyne natural product was isolated from a streptomycete isolated from the surface of a lichen, Cladonia uncialis.  It has interesting anti-tumor activities.  The highlight of the synthesis from Pierre van de Weghe from the Universite de Rennes in France is the intramolecular imino-alkyne diels alder to form a subsituted quinoline.  You can check out the synthesis in JOC.

JOC paper

Ugi Reaction to Make Dihydrophenanthridines

Last year, Jieping Zhu et al at CNRS published in nthe Beilstein Journal of Organic Chemistry on a four component Ugi reaction followed by an intramolecular C-H functionalization to form a diaryl C-C bond between an aryl halide and an aryl group.  Overall this is a useful method to make dihydrophenanthridines.

BJOC paper

Ni Catalyzed Hydroacylation

Michinori Suginome, Toshimichi Ohmura and co-workers from Kyoto University have recently published in JACS on a hydroacylation reaction catalyzed by Ni(c0d)2 (5 mol%) to potentially yield quaternary centers.  The substrate they reacted the aldehyde with was a vinyl cyclopropane which opened on the saturated end.

JACS paper

Cascade Heck Reaction

Yimin Hu et al at Anhui Normal University in China have recently published in Chemical Communications on a Heck-cascade reaction that leads to five contiguous stereocenters.  It’s not only an intermolecular coupling between an aryl halide and an alpha-beta-unsaturated amide, but also a cyclization that leads to the formation of two new rings – it almost looks like a Diels-Alder reaction except that there is an extra functional group introduced.

Chem Comm paper