Search results for "addition"
showing 10 items of 933 documents
Total Synthesis of (-)-Oxycodone via Anodic Aryl-Aryl Coupling.
2019
A fully regio- and diastereoselective electrochemical 4a–2′-coupling of a 3′,4′,5′-trioxygenated laudanosine derivative enables the synthesis of the corresponding morphinandienone. This key intermediate is further transformed into (−)-oxycodone through conjugate nucleophilic substitution for E-ring closure and [4 + 2] cycloaddition with photogenerated singlet oxygen to accomplish diastereoselective hydroxylation at C-14. The anodic transformation provides high yields and can be performed under constant current conditions both in a simple undivided cell or in continuous flow.
Thiourea-Catalyzed Domino Michael–Mannich [3+2] Cycloadditions: A Strategy for the Asymmetric Synthesis of 3,3′-Pyrrolidinyl-dispirooxindoles
2017
The asymmetric synthesis of trifluoromethylated 3,3′-pyrrolidinyl-dispirooxindole derivatives with four contiguous stereogenic centers, including two vicinal spiro-stereocenters, is described. Employing a bifunctional thiourea catalyst, a domino Michael–Mannich [3+2] cycloaddition occurs readily between isatin ketimines and isatin-derived enoates with good yields and very high stereoselectivities, providing a direct entry to the title compounds of potential medical value.
Fifteen operationally important decisions in the planning of biodiversity offsets
2018
Many development projects, whether they are about construction of factories, mines, roads, railways, new suburbs, shopping malls, or even individual houses, have negative environmental consequences. Biodiversity offsetting is about compensating that damage, typically via habitat restoration, land management, or by establishment of new protected areas. Offsets are the fourth step of the so-called mitigation hierarchy, in which ecological damage is first avoided, minimized second, and third restored locally. Whatever residual damage remains is then offset. Offsetting has been increasingly adopted all around the world, but simultaneously serious concerns are expressed about the validity of the…
Periphyton support for littoral secondary production in a highly humic boreal lake
2016
Steep stratification and poor light penetration in highly humic lakes typically restrict oxygenated littoral areas to narrow lake margins. However, in some instances, surrounding floating vegetation mats can sustain highly productive periphyton and more diverse invertebrate communities than pelagic areas. Little is known about how these littoral food webs function or the extent to which the pelagic and littoral food webs are coupled. We added 15N-labeled ammonium nitrate to the floating moss mat surrounding the littoral zone of Mekkojärvi, a small highly humic and fishless lake in southern Finland. Our goal was to increase the δ15N values of periphyton to investigate the diets of littoral i…
Transient Multivalent Nanobody Targeting to CD206-Expressing Cells via PH-Degradable Nanogels
2020
To target nanomedicines to specific cells, especially of the immune system, nanobodies can be considered as an attractive tool, as they lack the Fc part as compared to traditional antibodies and, thus, prevent unfavorable Fc-receptor mediated mistargeting. For that purpose, we have site-specifically conjugated CD206/MMR-targeting nanobodies to three types of dye-labeled nanogel derivatives: non-degradable nanogels, acid-degradable nanogels (with ketal crosslinks), and single polymer chains (also obtained after nanogel degradation). All of them can be obtained from the same reactive ester precursor block copolymer. After incubation with naï
Addition of thiols to the double bond of dipeptide C-terminal dehydroalanine as a source of new inhibitors of cathepsin C.
2017
Addition of thiols to double bond of glycyl-dehydroalanine and phenyl-dehydroalanine esters provided micromolar inhibitors of cathepsin C. The structure-activity studies indicated that dipeptides containing N-terminal phenylalanine exhibit higher affinity towards the enzyme. A series of C-terminal S-substituted cysteines are responsible for varying interaction with S1 binding pocket of cathepsin C. Depending on diastereomer these compounds most likely act as slowly reacting substrates or competitive inhibitors. This was proved by TLC analysis of the medium in which interaction of methyl (S)-phenylalanyl-(R,S)-(S-adamantyl)cysteinate (7i) with the enzyme was studied. Molecular modeling enabl…
Evolution of yeast populations during different biodynamic winemaking processes
2016
This work was performed to evaluate the evolution of indigenous yeasts during wine productions carried out following the principles of biodynamic agriculture. Five trials were designed with different technological interventions consisting of the addition of nitrogen (in the form of ammonium salt), thiamine salt, oxygen, and pied de cuvee at varying concentrations. Yeasts were estimated by haemocytometer chamber and plate counts and identified by sequencing of the D1/D2 domain of the 26S rRNA gene. The isolates identified as Saccharomyces cerevisiae were found to dominate must fermentations and were genetically differentiated by interdelta sequence analysis (ISA). Several non-Saccharomyces s…
Clinical whole-exome sequencing for the diagnosis of rare disorders with congenital anomalies and/or intellectual disability: substantial interest of…
2017
International audience; PurposeCongenital anomalies and intellectual disability (CA/ID) are a major diagnostic challenge in medical genetics—50% of patients still have no molecular diagnosis after a long and stressful diagnostic “odyssey.” Solo clinical whole-exome sequencing (WES) was applied in our genetics center to improve diagnosis in patients with CA/ID.MethodsThis retrospective study examined 416 consecutive tests performed over 3 years to demonstrate the effectiveness of periodically reanalyzing WES data. The raw data from each nonpositive test was reanalyzed at 12 months with the most recent pipeline and in the light of new data in the literature. The results of the reanalysis for …
The Wine: typicality or mere diversity? The effect of spontaneous fermentations and biotic factors on the characteristics of wine
2016
Abstract Wine is probably one of the main fermented beverages for which the recognition of the “territoriality” is fundamental for its appreciation. The sensory profile of wine is significantly affected by microbial activities, and indigenous microorganisms may significantly contribute to the expression of wine typicality. The microbial ecology of wines is complex and includes several species and strains of yeasts, bacteria and molds. Several works showed the positive effects of spontaneous fermentations on the quality of wine as a consequence of the growth of different species and/or strains together at high levels. Furthermore, a new style of “natural” winemaking is gaining importance, si…
Suggestions for revised scoring of the Tower of Hanoi test
2000
Detailed time and error analyses of the Tower of Hanoi (TOH) test was performed using four repeated assessments of eight children (ages 9-12 years), who had perceptual and problem solving deficits. The time before each move was measured. In addition to the traditionally counted time scores, new, relative time scores were computed in order to separate the planning time from the general reaction speed. New error scores were defined and sum scores of serious errors (perserative moves, illegal moves, and wrong results) and mild errors (self-corrected moves, almost performed moves, and interrupted trials) were computed. The relative planning time correlated positively with the achieved score, a…