Directing groups have been widely used in recent years to achieve control over all aspects of reaction selectivity in a wide range of transformations involving transition-metal catalysis and organometallic reagents. In cases when the existing functional group within a substrate is unsuited to achieve efficient intramolecular delivery of a reagent or catalyst, the specific introduction of an appropriately designed removable reagent-directing group can be a solution to this problem. In this Review we give an overview of the state of the art in this area, including the stoichiometric and catalytic use of directing groups.

Despite its industrial importance metal-catalyzed hydroformylation has not found much application in organic synthesis. This may be primarily due to the difficulty in controlling selectivity issues in the course of this interesting carbon-carbon bond forming reaction. In the last decade a number of excellent solutions to these problems have been devised. Thus, frontiers of chemo-, regio-, diastereo-and enantioselectivity control in the course of the hydroformylation and their application in organic synthesis are the major focus of this review. Mechanistic and conceptual background have been included where appropriate. Additionally, recent progress in the field of domino reactions employing the hydroformylation as a key step is covered.

A new concept for the construction of bidentate ligands for homogeneous metal complex catalysis is described. The concept relies on the self-assembly of monodentate ligands through hydrogen bonding. As a prototype of such systems, 6-diphenylphosphanyl-2-pyridone (6-DPPon) was shown to form a chelate in the coordination sphere of a transition metal center through unusual pyridone/hydroxypyridine hydrogen bonding (X-ray). This hydrogen bonding stays intact in a catalytic reaction as proven upon highly regioselective hydroformylation of terminal alkenes. Regioselectivities and reactivities observed rank the 6-DPPon/rhodium system among the most active and regioselective catalysts for n-selective hydroformylation of terminal alkenes.

Allylic alcohols represent an important and highly versatile class of chiral building blocks for organic synthesis. This Review summarizes the plethora of methods developed for the catalytic asymmetric synthesis of enantioenriched allylic alcohols. These include: dynamic kinetic resolution (DKR/DKAT), nucleophilic 1,2-addition to carbonyl groups, allylic substitution, oxidation of C-H bonds, the addition of O nucleophiles to π systems, reduction of unsaturated carbonyl compounds, and an alternative route from enantioenriched propargylic alcohols. Furthermore, these catalytic asymmetric processes are exemplified by their applications in the syntheses of complex molecules such as natural products and potential therapeutic agents.