Designer Surfactant For Micellar Catalysis
A novel amphiphilic molecule provides a promising
platform for carrying out greener ring-closing metathesis
reactions in water
Stephen K. Ritter
A newly designed molecule that functions as a solvent and homogeneous catalyst rolled
into one is a promising platform for carrying out greener ring-closing metathesis reactions
in water, according to Bruce H. Lipshutz and Subir Ghorai of the University of California,
Santa Barbara, who created the amphiphile (Org. Lett. 2009, 11, 705). Polyoxyethanyl
ubiquinyl sebacate, or PQS, is made up of a hydroquinone ring that has lipophilic
polyprenoid and hydrophilic polyethylene glycol side chains. The ring also has a hydroxyl
group that provides a spot for covalently linking a transition-metal catalyst. Given the
lipophilic-hydrophilic combination, PQS forms nanoscale micelles in water, which are
ideal nanoreactors for ring-closing metathesis reactions, the researchers note. Lipshutz and
Ghorai attached a ruthenium carbene catalyst to PQS and tested the micellar system by
carrying out a set of reactions using water-insoluble dienes as substrates. They achieved
better than 92% yields running the reactions in air at room temperature, even after
recycling the system 10 times. PQS provides a "conceptually new, green platform for
carrying out micellar catalysis," Lipshutz says.