Stereoselective synthesis of artificial C-nucleosides

Reported herein is a conceptually new synthetic route to 1’-aryl C-ribofuranosides and their 2’,3’-didehydro 2’,3’-dideoxy (D4) analogues. We have successfully implemented a divergent synthetic route capable to reach two important, biologically significant groups of compounds. The first two strategic transformations are common for both families of target compounds (asymmetric allylic substitution, and ring-closing metathesis). D4 C nucleoside analogues are synthesised in a three step procedure, and 1’-aryl ribofuranoses are constructed in a four step procedure. The target compounds were prepared in an excellent enantio and diastereopurity, in good overall yields. The yield in the synthesis of 1’-aryl-2’,3’-didehydro-1’,2’,3’-trideoxyribofunanoses is up to 46% over all the reaction steps. The overall yield of the 1’-arylribofuranoses is up to 42%. All the strategic transformations rely on catalytic oranometallic reactions employing group 8a transition metals. All the reactions have been optimized with a view of maximal atom efficiency and environmental impact. In summary, our new methodology is perfectly suitable for the synthesis of 1’ arylribofuranoses, and their D4 analogues, bearing non-ortho-substituted aromatics and hereroaromatics, lacking coordinating (nitrogen) substituents or heteroatoms. In this point of view the most promising target application is the synthesis of lipophilic isosters of ribonucleosides for the RNA studies

Preparation of Boc-protected cinnamyl-type alcohols: A comparison of the Suzuki-Miyaura coupling, cross-metathesis, and Horner-Wadsworth-Emmons approaches and their merit in parallel synthesis

Three synthetic strategies for the construction of tert-butyl (E)-3-arylprop-2-en-1-ol carbonates are described. Complementary approaches employing Suzuki-Miyaura coupling and cross-metathesis reaction gave moderate yields of the title compounds in one-step, both methods are suitable for high-throughput and parallel chemistry. A detailed investigation into the Suzuki-Miyaura coupling reaction is provided along with the studies on the synthesis of pinacolyl 1-(tert-butyloxycarbonyl) propenol-3-ylboronate, the key building block. Conventional synthesis of the title compounds via the Horner-Wadsworth-Emmons reaction as a key step in a three-step-one-purification protocol was optimized and the results are compared with those of the latter reactions

Added value of manure (co-)digestion in light of GHG emission abatement: moving beyond COP21

In the EU alone already approximately 1,27 billion tons of manure are produced annually. Not surprisingly, this type of agro side stream has been recognized for its considerable potential for producing renewable energy, with anaerobic digestion often as the preferred pathway. Nevertheless, fossil energy replacement is not the only added value that can be associated to energetic conversion of manure. When manure is frequently and freshly digested rather than stored for prolonged times, the avoided emissions of methane from storage also significantly contribute to reducing GHG as methane itself is 21 times more harmful than CO2 itself towards global warming. Better to recover and turn into energy than allow slow release in the air, as is usually the case in current practices in animal husbandry. In addition, digestion will effectively mineralize organic nitrogen and phosphorus rendering them more available for plant uptake. Novel pathways for processing digestate can therefore result in effective substitution of mineral fertilizers derived from fossil resources, again resulting in reduced primary energy use. Finally, the recalcitrant (humus) fractions of organic matter present in digested manure tend to remain stable in soil for considerable periods of time. Current proposals to the COP21 carbon accounting include carbon sequestration of such recalcitrant organic matter as a carbon sink. Simultaneously soil fertility and soil quality themselves are improved by improving soil structure, soil cation exchange capacity (CEC) and adhesion surface for soil microbial life. The sum of all before mentioned qualities make manure (co-)digestion an prime strategy when aiming towards GHG emission abatement beyond the scope of mere substitution of fossil energy by renewable energy. Because of this, the CO2 eq. reduction per MWh of energy produced in systems making use of anaerobic digestion of manure exceeds that of any other type of renewable energy. Regional/national implementation plans beyond COP21 agreements should take this into account when developing sustainable policy roadmaps. This study focuses on the qualitative description of the merits associated to manure digestion as well their quantification