Regioselective Beckmann rearrangements of furanoside and pyranoside-derived oximes

The Beckmann rearrangement is a useful reaction employed to provide access to amides from oxime substrates. Applied to cyclic structures, the Beckmann rearrangement leads to ring expansion and allows access to cyclic lactams. Our investigations focused upon the synthesis of glycoside-derived lactams from oxime precursors. In probing a range of conditions, we observed that 2,4,6-trichloro[1,3,5]triazine (TCT) was an effective and mild promoter of the rearrangement affording pyrano- and heptanoside lactam products with excellent regioselectivities

Long-term changes in the tree and shrub layers of a British nature reserve and their relevance for woodland conservation management

Changes in the woodland extent over the last 200 years were assessed from old maps for a 100 ha woodland nature reserve in southern Britain. More detailed changes in the composition and structure of the tree and shrub layers were measured using data from 95 permanent vegetation plots (10 × 10 m) distributed across the reserve at the intersections of a 100 m grid. These were recorded in 1973, 1992 and 2009. The woodland area has more than doubled since the 18th century, but whereas the pre-1800 woodland was mainly Fagus sylvatica the more recent woodland was initially predominantly conifer plantation. These plantations have since developed into mainly broadleaved high forest of Fraxinus excelsior and Acer pseudoplatanus. Changes on the site are the combination of active interventions through management and natural processes (differential species growth, death from disease, windthrow, herbivore damage). Further changes are likely in future in particular from ash dieback (Hymenoscyphus fraxineus) and climate change impacts. Many of the changes seen on this reserve are mirrored in woods elsewhere in Britain and Europe. Over periods of a few decades and at the whole-reserve scale the woods can be considered to be relatively stable at the plot level, or over time-scales of centuries they are very dynamic. Whether woods are judged to be resilient must include definition of the temporal and spatial scales

Estimating the range of influence of point defects on Cu(110) surface states

By utilising Reflection Anisotropy Spectroscopy (RAS) and Scanning Tunnelling Microscopy (STM) measurements of the ion bombarded Cu(110) surface at low temperatures, we have developed a simple methodology for estimating the surface area over which a single atomic defect locally influences surface states such that the contribution to the intensity of the 2.1 eV RAS peak involving these states is destroyed. We estimate this area to be approximately equal to that of a circle with a radius of 0.75 nm: an area in the surface plane equivalent to that of around 19 unit cells. By employing STM to accurately determine the coverage and spatial distribution of irradiation-induced defects, we are able to develop a coherent analytical approach to model this system