meta-Selective C−H Borylation of Benzylamine-, Phenethylamine-, and Phenylpropylamine-Derived Amides Enabled by a Single Anionic Ligand

Selective functionalization at the meta position of arenes remains a significant challenge. In this work, we demonstrate that a single anionic bipyridine ligand bearing a remote sulfonate group enables selective iridium-catalyzed borylation of a range of common amine-containing aromatic molecules at the arene meta position. We propose that this selectivity is the result of a key hydrogen bonding interaction between the substrate and catalyst. The scope of this meta-selective borylation is demonstrated on amides derived from benzylamines, phenethylamines and phenylpropylamines; amine-containing building blocks of great utility in many applications.We are grateful to the EPSRC and Pfizer for a CASE studentship (H.J.D.), the EPSRC (EP/N005422/1, G.R.G.) and the Royal Society for a University Research Fellowship (R.J.P.)

Ion Pair-Directed C-H Activation on Flexible Ammonium Salts: Meta-Selective Borylation of Quaternized Phenethylamines and Phenylpropylamines

Ion pairing has unexplored potential as a key catalyst-substrate interaction for controlling regioselectivity and site-selectivity in transition metal catalysis, particularly in the area of C-H activation. However, there is a significant perceived challenge that has meant that few have investigated this approach to date – that of the low directionality, which could present an insurmountable challenge if seeking positional selectivity on flexible substrates. Herein, we demonstrate that even flexible substrates with several freely rotatable bonds undergo ion pair-directed CH borylation with good to excellent levels of regiocontrol for the arene meta position. Furthermore, we demonstrate that in specially designed competition substrates, ion pair direction prevails over competing hydrogen bond direction. We anticipate that these findings will inspire the greater incorporation of ion-pairing into site-selective catalytic strategies

Access to the Meta Position of Arenes through Transition Metal Catalysed C-H Bond Functionalisation: A Focus on Metals Other Than Palladium

The elaboration of simple arenes in order to access more complex substitution patterns is a crucial endeavor for synthetic chemists, given the central role that aromatic rings play in all manner of important molecules. Classical methods are now routinely used alongside stoichiometric organometallic approaches and, most recently, transition metal catalysis in the range of methodologies that are available to elaborate arene C-H bonds. Regioselectivity is an important consideration when selecting a method and, of all those available, it is arguably those that target the meta postion that are fewest in number. The rapid development of transition metal-catalysed C-H bond functionalisation over the last few decades has opened new possibilities for meta-selective C-H functionalisation through the diverse reactivity of transition metals and their compatibility with a wide range of directing groups. The pace of discovery of such processes has grown rapidly in the last five years in particularly and it is the purpose of this review to examine these but in doing so to place the focus on metals other than palladium, the specific contributions of which have been very recently reviewed elsewhere. It is hoped this will serve to highlight to the reader the breadth of current strategies and mechanisms that have been used to tackle this challenge, which may inspire further progress in the field.We are grateful to the Royal Society for a University Research Fellowship (R.J.P.), AstraZeneca for a PhD studentship (M.T.M.) through the AZ-Cambridge PhD Program and the EPSRC (G.R.G, EP/N005422/1)

Patterns of crop damage by wild boar (Sus scrofa)in Luxembourg over a 10-year period

In many European countries, the wild boar (Sus scrofa) is often associated with crop damage. In this study, we analyse data relating to 13,276 cases of wild boar damage to agricultural crops over a 10-year period in Luxembourg (an area of 2,586 km2 in Western Europe). Results show that (1) damage is more severe in this area than in others; (2) damage to permanent grassland is far more frequent and more severe than damage to annual crops; (3) trichomatous crops such as barley are avoided; (4) damage is seasonally distributed according to type of crop; (5) damage is distributed spatially in a non-uniform manner; (6) damage intensity is significantly correlated with wild boar hunting bags, both over time and space. We suggest that wild boar management strategy should always take into account the issue of damage to agricultural crops. Our results imply that measures for preventing or reducing damage should be more targeted in time and space and that adjustments to cropping patterns should contribute towards a reduction of wild boar damage. © 2008 Springer-Verlag