Geological structure, recharge processes and underground drainage of a glacierised karst aquifer system, Tsanfleuron-Sanetsch, Swiss Alps

The relationships between stratigraphic and tectonic setting, recharge processes and underground drainage of the glacierised karst aquifer system ‘Tsanfleuron-Sanetsch' in the Swiss Alps have been studied by means of various methods, particularly tracer tests (19 injections). The area belongs to the Helvetic nappes and consists of Jurassic to Palaeogene sedimentary rocks. Strata are folded and form a regional anticlinorium. Cretaceous Urgonian limestone constitutes the main karst aquifer, overlain by a retreating glacier in its upper part. Polished limestone surfaces are exposed between the glacier front and the end moraine of 1855/1860 (Little Ice Age); typical alpine karrenfields can be observed further below. Results show that (1) large parts of the area are drained by the Glarey spring, which is used as a drinking water source, while marginal parts belong to the catchments of other springs; (2) groundwater flow towards the Glarey spring occurs in the main aquifer, parallel to stratification, while flow towards another spring crosses the entire stratigraphic sequence, consisting of about 800m of marl and limestone, along deep faults that were probably enlarged by mass movements; (3) the variability of glacial meltwater production influences the shape of the tracer breakthrough curves and, consequently, flow and transport in the aquife

Enantioselective copper-catalyzed conjugate addition to sensitive Michael acceptors and application to natural product synthesis use in perfumes and flavours chemistry

Enantioselective Cu-catalyzed conjugate addition of organometallic reagents to Michael acceptors is one of the most trailblazing and powerful method in organic chemistry to acquire enantioenriched β-substituted natural or unnatural adducts through C-C bond formation. Although numerous research results have been published with α,β-unsaturated compounds such as carbonyl derivatives, sulfones, nitroalkenes, and nitroenynes to date, a wide range of discoveries in this field is still to be made. However, in order to synthesize new families of compounds and complex synthons at the same time, new asymmetric organic reactions or methodologies with more sensitive substrates must be investigated. The interest in the development of new synthetic methodologies with more challenging substrates is related to the preparation of natural and unnatural adducts through a direct access of a large variety of important chiral compounds from the same starting material. To achieve this purpose, we investigated a new copper-catalyzed asymmetric conjugate addition with various organometallic reagents to functionalized α,β-unsaturated aldehydes and β,γ-unsatured-α-ketoester

Blue LED Mediated C-H and N-H Insertion of Indoles into Aryldiazoesters and Iodonium Ylides: FH-HES Universities of Applied Sciences

Herein we have discussed projects related to blue LED mediated C-H and N-H insertion reaction in indoles and related heterocycles with aryl diazoesters and iodonium ylides as sources of carbenes. Blue LED effectively facilitates these conversions and was optimized from the option of numerous other LED lights. No metal catalysts were required. The reactions provide formation of differently alkylated indoles, pyrroles and furans. Control experiments and DFT calculation were used to understand the mechanism of reactions. As an application compounds bearing azepino[4, 5-b]indole and spiropiperidino indole building blocks were synthesized from the alkylated products

Enantioselective Copper-Catalyzed Conjugate Addition of Trimethylaluminium to β,γ-Unsaturated α-Ketoesters

Not a cop out: The copper-catalyzed asymmetric conjugate addition of organometallic reagents to Michael acceptors is an important methodology for forming a CC bond in an enantioselective manner. Such an addition of Me3Al to β,γ-unsaturated α-ketoesters is described to proceed in high yield and selectivity. CuTC=copper(I) thiophene-2-carboxylate

Construction of Bicyclo[3.2.1]octanes with Four Stereogenic Centers by Organocatalytic Domino Michael/Aldol Reaction

An enantio- and diastereoselective organocatalytic domino Michael/Aldol reaction for the direct preparation of synthetically and medicinally relevant bicyclo[3.2.1]octane derivatives with four stereogenic centers, including two quaternary carbons, has been described. The reaction tolerates a large variety of substituents on β,γ-unsaturated 1,2-ketoesters and cyclic 1,3-ketoesters. It allows for the formation of various bicyclo[3.2.1]octanes in good yields (53–98%), diastereoselectivities (1:1 to 5:1 dr), and enantioselectivities (up to 95:5 ee)

Enantioselective Copper-Catalyzed Conjugate Addition of Trimethylaluminum to β,γ-Unsaturated α-Ketoamides: Efficient Access to γ-Methyl-Substituted Carbonyl Compounds

Picture perfect: By using the reagent trimethylaluminium and β,γ-unsaturated α-ketoamides, 1,4-adducts were obtained with perfect 1,4-regioselectivity and good to excellent yields and ee values. The potential synthetic utility of the methodology was highlighted by preparation of γ-methyl-substituted carbonyls, key synthons to many natural products. binap=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl, TC=thiophene carboxylate

Copper-catalyzed Asymmetric Conjugate Addition to Challenging Michael Acceptors and Synthesis of Relevant Target Molecules

We report herein the enantioselective Cu-catalyzed conjugate addition of organometallic reagents to sensitive Michael acceptors and their application to the synthesis of relevant target molecules. This is one of the most important methodologies to form a C-C bond in an enantioselective manner. A wide range of α,β-unsaturated aldehydes and β,γ-unsaturated-α-ketoesters has been successfully used. Reactivity, regio- and enantioselectivities were strongly dependent on the reaction conditions, therefore moderate to very good results were obtained. Furthermore, γ-substituted-α-ketoesters were used as chiral building blocks for further derivatization with complete retention of the chiral information to obtain key compounds

Copper-catalysed kinetic resolution of cyclic alkenyl cyclopropane malonates with organoaluminium and Grignard reagents

We report herein the first copper-catalysed kinetic resolution of alkenyl cyclopropane malonates with organoaluminium and Grignard reagents. The conjugate products were exclusively obtained on five- and six-membered-ring substrates. After optimization of the reaction conditions, we observed good conversions and enantiomeric excesses using ferrocene-based ligands on five-membered-ring substrates, and phosphoramidite ligands on six-membered rings

Blue LED mediated intramolecular C–H functionalization and cyclopropanation of tryptamines ::synthesis of azepino[4, 5-b]indoles and natural product inspired polycyclic indoles

We report a novel blue LED mediated intramolecular C–H functionalization of tryptamine derivatives to generate azepino[4, 5-b]indoles (4) in moderate to good yields. By altering the substitution at the tryptamine nitrogen, intramolecular cyclopropanation is achieved in high yields under the same reactions condition to provide natural product inspired polycyclic indoles (6), which are further transformed to spiropiperidino (5 and 8) indoles in decent yields. The mechanism of formation of the compounds was investigated through DFT studies