The epoxide deoxygenation reaction is formally the reverse of theepoxidation reaction. Compared to epoxidation, which has reached its fullmaturity, epoxide deoxygenation has not been as intensively developed.Among the few deoxygenation reagents, a handful are catalytic in a metalcomplex, show high stereospecificity and operate under mild conditions. Acommon feature of all...
In situ, reduction of Cp*ReO₃ by PPh₃ to form (Cp*ReO)₂(μ-O)₂ allows catalytic deoxygenation of epoxides, however, conproportionation between Reⱽ and Reⱽᴵᴵ species to form clusters of ((Cp*Re)₃(μ-O)₆}²⁺(ReO₄⁻)2 and new compound {(Cp*Re)₃(μ²-O)₃(μ³-O⁾³ReO₃}⁺(ReO₄⁻) leads to removal of rhenium from the catalytic cycle and loss of activity, The epoxide deoxygenation mediated by (Cp*ReO)₂(μ-O)₂...
In situ reduction of hydrido-tris-(3,5-dimethylpyrazolyl)borato(trioxo) rhenium(V) with triphenylphosphine or triethylphosphite leads to a reactive rhenium(V) species that catalytically deoxygenates epoxides at 75-105°C. The reaction is stereospecific, except for trans- and cis-butene oxide which formed minor amounts of the opposite isomer. A variety of different functional groups were tolerated and even...
A series of compounds, 7-8 and 20-25, were tested as competitive inhibitors of 2,5-dihydroxyacetanilide epoxidase I (DHAE I) and DHAE II. A Hammett plot was constructed for each enzyme to determine the effect of electron density on inhibition. DHAE I gave a linear, highly correlated plot (r²=0.91) that signifies the...
The rhenium (V) complex Tp'ReO₂ (Tp' = hydrido-tris-(3,5-
dimethylpyrazolyl)borate), generated in situ from PPh₃ reduction of
Tp'Re0₃, reacts with small ring heterocycles such as epoxides and
episulf ides. The strained trans-cyclooctene ring provides an unusual
thermodynamic bias against direct atom transfer, but trans-cyclooctene
oxide still produces substantial amounts of trans-cyclooctene....
The gut microbiome has been previously implemented in a number of diseases. Of note is its substantial role in metabolic syndrome, which encapsulates a group of conditions that increase the risk of cardiovascular disease, type 2 diabetes, and stroke. Understanding the causal relationships between the gut microbiome and host processes...
Timber harvesting practices can increase fine sediment inputs to streams due to increased hillslope soil erosion and mass wasting of roads, hillslopes, and stream channels. Excessive fine sediment depositions have been shown to impact aquatic ecosystems, fish habitat, and downstream community water supply. Despite these deleterious impacts, the influence of...
The rhenium dithiodiolate, Hydrido-tris-(3 ,5-dimethyl- 1 -pyrazol yl) borato(ethane- 1 ,2-dithiodiolato)(oxo)rheni um(V), and Hydrido-tris-(3 ,5-dimethyl- 1 -pyrazolyl)borato(phenylethanedithiodiolato)(oxo)rhenium(V), were synthesized by reductive cyclocondensation of alkane-1,2-dithiols with Tp'Re0₃ in a one pot fashion. The rhemium monothiodiolate, Hydrido-tris-(3 ,5-dimethyl- 1 -pyrazolyl) borato(ethane- 1 ,2-monothiodiolato)(oxo)rhenium(V), and Hydrido-tris-(3 ,5- dimethyl- 1 -pyrazolyl)borato(propanemonothiodiolato)(oxo)rhenium(V), were also synthesized...
Airborne discrete-return lidar is an active remote sensing technology capable of obtaining accurate, fine-resolution three-dimensional measurements over large areas. Discrete-return lidar data produce three-dimensional object characterizations in the form of point clouds defined by precise x, y and z coordinates. The data also provide intensity values for each point that...
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Kevin D. Boston
Airborne discrete-return lidar is an active remote sensing technology