We analyze cost developments for technologies required to produce renewable fuels by applying learning curves.

[Structure: see text] A novel P,N-type ligand family (ClickPhine) is disclosed that is easily accessible using the Cu(I)-catalyzed azide-alkyne "click" cycloaddition. A diverse set of ligands was made in just three steps from readily available starting materials to give several homogeneous and a heterogeneous catalyst. Preliminary experiments show the efficacy of these ligands in the Pd-catalyzed allylic alkylation reaction.

A proper copper catalyst with a chiral pyridine‐2,6‐bisoxazoline (pybox) ligand was used to convert a variety of propargylic acetates with aromatic side chains (R=Ar) into their amine counterparts in high yield and with good selectivity (up to 88 % ee). The resulting chiral propargylic amines can be elaborated further into P,N ligands (see scheme; DIPEA=diisopropylethylamine).

Lowering the overpotential required for water oxidation is of paramount importance for the efficient production of carbon-neutral fuels. This article highlights the intrinsic influence of the water oxidation mechanism used by molecular catalysts on the theoretically achievable minimal overpotential, based on scaling relationships typically used for heterogeneous catalysts. Due to such scaling relationships, catalysts that operate through the water nucleophilic attack mechanism have a fundamental minimal overpotential of about 0.3 V, whereas those that follow the dinuclear radical oxo coupling mechanism should in principle be able to operate with a lower overpotential. Therefore, it is recommended to design catalysts operating through the latter mechanism to achieve very efficient water oxidation systems.

Besides being a versatile entity for further chemical transformations, the propargylic subunit is also part of various natural products, fine chemicals, and synthetic pharmaceuticals. Propargylic substitution reactions, however, are rather unexplored. An overview of this emerging field is presented. We especially focus on experimental results that deal with catalyzed substitutions of propargylic alcohols and their derivatives. Finally, some enantioselective propargylic substitution methods are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A copper catalyst with a chiral pyridine-2,6-bisoxazoline (pybox) ligand was used to convert a variety of propargylic esters with different side chains (R=Ar, Bn, alkyl) into their amine counterparts in very high yields and with good enantioselectivities (up to 90% enantiomeric excess (ee)). Different amine nucleophiles were applied in the reactions and the highest enantioselectivities were obtained for aniline and its analogues. Interestingly, some carbon nucleophiles could also be used and with indoles excellent ee values were obtained (up to 98% ee). The versatility of the propargylic amines obtained was demonstrated by their further elaboration to formal total syntheses of the antibiotic (+)-anisomycin and the cytokine modulator (-)-cytoxazone.

In this study, we report a series of DIMPhos ligands L1-L3, bidentate phosphorus ligands equipped with an integral anion binding site (the DIM pocket). Coordination studies show that these ligands bind to a rhodium center in a bidentate fashion. Experiments under hydroformylation conditions confirm the formation of the mononuclear hydridobiscarbonyl rhodium complexes that are generally assumed to be active in hydroformylation. The metal complexes formed still strongly bind the anionic species in the binding site of the ligand, without affecting the metal coordination sphere. These bifunctional properties of DIMPhos are further demonstrated by the crystal structure of the rhodium complex with acetate anion bound in the binding site of the ligand. The catalytic studies demonstrate that substrate preorganization by binding in the DIM pocket of the ligand results in unprecedented selectivities in hydroformylation of terminal and internal alkenes functionalized with an anionic group. Remarkably, the selectivity controlling anionic group can be even 10 bonds away from the reactive double bond, demonstrating the potential of this supramolecular approach. Control experiments confirm the crucial role of the anion binding for the selectivity. DFT studies on the decisive intermediates reveal that the anion binding in the DIM pocket restricts the rotational freedom of the reactive double bound. As a consequence, the pathway to the undesired product is strongly hindered, whereas that for the desired product is lowered in energy. Detailed kinetic studies, together with the in situ spectroscopic measurements and isotope-labeling studies, support this mode of operation and reveal that these supramolecular systems follow enzymatic-type Michaelis-Menten kinetics, with competitive product inhibition.

A series of iridium-based complexes have been evaluated in Ce(IV)-driven water oxidation catalysis. Detailed kinetic data have been obtained from UV−vis stopped-flow experiments, and these data have been analyzed using reaction progress kinetic analysis. The graphical plots show that there are three clear phases in the reaction: catalyst activation, water oxidation catalysis, and cerium concentration controlled catalysis at the end of the reaction. The ligand attached to the IrCp* complex has a clear influence on both the activation as well as the catalysis. Some bidentate ligands result in relatively slow catalysis, and the first-order in iridium supports the presence of mononuclear active species; however, other bidentates form the more active dinuclear species. Monodentate ligands allow the formation of bis-μ-oxo bridged dimeric species, supported by kinetics displaying 1.6-order in [Ir], leading to high reaction rates.