Gráinne C. Hargaden

Recent applications of oxazoline-containing ligands in asymmetric catalysis.

Compounds containing a chiral oxazoline ring have become one of the most successful, versatile, and commonly used classes of ligands for asymmetric catalysis due to their ready accessibility, modular nature, and applicability in a wide range of metal-catalyzed transformations. The large majority of these ligands are derived from readily available chiral amino alcohols in short, high yielding synthetic sequences. As a consequence, the enantiocontrolling stereocenter resides on the carbon atom neighboring the coordinating nitrogen of the oxazoline ring and, therefore, in close proximity to the metal active site, thus having a direct influence on the stereochemical outcome of the reaction. Since the first report in 1986 of the use of chiral oxazolinebased ligands in asymmetric catalysis, a diverse range of ligands with one, two, or more oxazoline rings incorporating various heteroatoms, additional chiral elements, and specific structural features have been used with great success in a wide range of asymmetric reactions. This review reports on the use of such ligands in homogeneous metal-catalyzed asymmetric synthesis since 2004, when the area was last reviewed.1 We cover, to the best of our knowledge, all applications of oxazolinecontaining ligands reported in the literature until the end of 2007. This review will be structured in the same manner as our 2004 review, as we classify ligands not by the reaction to which their metal complexes have been applied but by the nature of the denticity, chirality, and donor atoms involved. In this manner, the continued development of ligand architectural design can be more easily monitored.

Recent mechanistic developments and next generation catalysts for the Sonogashira coupling reaction

The Pd-catalyzed Sonogashira reaction is a powerful method for the formation of Csp2–Csp bonds and has found application in a wide variety of areas including medicinal chemistry, agrochemistry, materials and electronics. Development of competent catalysts for the Sonogashira reaction is a particular scientific challenge since it is traditionally a di-metallic-mediated homogeneous catalytic process including some major drawbacks. This review provides a concise overview of the mechanistic aspects of the Cu co-catalyzed, Cu-free and Au-catalyzed Sonogashira coupling processes. More recent developments and next generation catalysts for the Sonogashira reaction are also presented. These include non transition-metal catalysts, metal free couplings and photo-induced protocols. Finally, the application of metal nanoparticles in Sonogashira reactions is presented. These include Pd nanoparticles, Pd bi- and tri-metallic nanoparticles, magnetically separable Pd/Fe3O4 nanoparticles, Ru nanoparticles and Au nanoparticles.

The application of bis(oxazoline) ligands in the catalytic enantioselective methallylation of aldehydes

A series of symmetric and non-symmetric bis(oxazoline) ligands were applied in the Nozaki-Hiyama-Kishi methallylation of a range of aromatic and aliphatic aldehydes. A non-symmetrical ligand with tert-butyl/benzyl-substituted oxazolines provided the highest enantioselectivity of 99.5% for the methallylation of benzaldehyde.

Synthesis and modification of octafluoro[2.2]paracyclophane (parylene AF4)

Parylenes are a class of organic compounds which have gained significant attention due to their application as coatings in areas such as medical devices and electronics. This review highlights the development of synthetic pathways to Octafluoro[2.2]Paracyclophane, commonly referred to as parylene AF4. Methods which have been used to functionalise AF4 are also presented.