113 research outputs found
Covid-19 and tracing methodologies: A lesson for the future society
As the new coronavirus (SARS-CoV-2) surged across the globe, new technical solutions have supported policy makers and health authorities to plan and modulate containment measures. The introduction of these solutions provoked a large debate which has focused on risks for privacy and data protection. In this paper we offer an analysis of the available technical approaches and provide new arguments to move beyond the ongoing discussions. In particular, we argue that the past debate missed the opportunity to highlight the societal aspects of privacy and to stimulate a broader reflection on the actions needed to serve the good of society. With this paper, as well as providing an accessible review of the technical and legal aspects of the proposed solutions, we aim to offer new stimuli to reconsider contact tracing and its role in helping countries navigate the current pandemic
A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters
We report herein the use of a dual catalytic system comprising of a Lewis base catalyst such as quinuclidin-3-ol or 4- dimethylaminopyridine combined with a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react via radical addition with electron-deficient olefins to efficiently form C–C coupled products in a redox neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either boronic esters or the trimeric form of the boronic acids (boroxines) in solution.We are grateful to Novartis Pharma AG (F.L.), the Erasmus Scholarship Scheme (L.G. and S.J.), and the EPSRC (S.V.L., Grants EP/K009494/1, EP/K039520/1, and EP/M004120/1) for financial support. U.K.S. and D.S. are thankful to the University of Leuven for postdoctoral funding and the FWO for a visiting postdoctoral scholarship (U.K.S.) at the University of Cambridge. E.V.V.d.E. would like to thank the Ministry of Education and Science of the Russian Federation for financial support (agreement number 02.a03.0008). We thank Dr. Berthold Schenkel and Dr. Gottfried Sedelmeier for insightful discussions. We thank Merck Rahway USA for the generous gift of the PC(1) photoredox catalyst
A classification prognostic score to predict OS in stage IV well-differentiated neuroendocrine tumors
No validated prognostic tool is available for predicting overall survival (OS) of patients with well-differentiated neuroendocrine tumors (WDNETs). This study, conducted in three independent cohorts of patients from five different European countries, aimed to develop and validate a classification prognostic score for OS in patients with stage IV WDNETs. We retrospectively collected data on 1387 patients: (i) patients treated at the Istituto Nazionale Tumori (Milan, Italy; n = 515); (ii) European cohort of rare NET patients included in the European RARECAREnet database (n = 457); (iii) Italian multicentric cohort of pancreatic NET (pNETs) patients treated at 24 Italian institutions (n = 415). The score was developed using data from patients included in cohort (i) (training set); external validation was performed by applying the score to the data of the two independent cohorts (ii) and (iii) evaluating both calibration and discriminative ability (Harrell C statistic). We used data on age, primary tumor site, metastasis (synchronous vs metachronous), Ki-67, functional status and primary surgery to build the score, which was developed for classifying patients into three groups with differential 10-year OS: (I) favorable risk group: 10-year OS >= 70%; (II) intermediate risk group: 30% <= 10-year OS < 70%; (III) poor risk group: 10-year OS < 30%. The Harrell C statistic was 0.661 in the training set, and 0.626 and 0.601 in the RARECAREnet and Italian multicentric validation sets, respectively. In conclusion, based on the analysis of three 'field-practice' cohorts collected in different settings, we defined and validated a prognostic score to classify patients into three groups with different long-term prognoses
Chemoselective Peptide Backbone Diversification and Bioorthogonal Ligation by Ruthenium-Catalyzed C−H Activation/Annulation
The field of peptide derivatization by metal-catalyzed C−H activation has been mostly directed to modify the side chains, but poor attention has been given to the peptide backbone. Here we report a ruthenium-catalyzed C−H activation/annulation process that can chemoselectively modify the peptide backbone producing functionalized isoquinolone scaffolds with high regioselectivity in a rapid and step-economical manner. This strategy is characterized by racemization-free conditions and the production of fluorescent peptides, and peptide conjugates to drugs, natural products and other peptide fragments, providing a chemical approach for the construction of novel peptide-pharmacophore conjugates. Mechanistic studies suggest that amide bonds of peptide backbone act as the bidentate directing group to promote the C−H activation/annulation process. This report provides an unprecedented example of peptide backbone diversification and bioorthogonal ligation exploiting the power of ruthenium-catalyzed C−H activation. (Figure presented.). © 2021 Wiley-VCH Gmb
Metal-mediated post-Ugi transformations for the construction of diverse heterocyclic scaffolds
The Ugi-4CR is by far one of the most successful multicomponent reactions leading to high structural diversity and molecular complexity. However, the reaction mostly affords a linear peptide backbone, enabling post-Ugi transformations as the only solution to rigidify the Ugi-adduct into more drug like species. Not surprisingly, the development of these transformations, leading to new structural frameworks, has expanded rapidly over the last few years. As expected, palladium-catalyzed reactions have received the foremost attention, yet other metals, particularly gold complexes, are fast catching up. This tutorial review outlines the developments achieved in the past decade, highlighting the modifications that are performed in a sequential or domino fashion with emphasis on major concepts, synthetic applications of the derived products as well as mechanistic aspects.status: publishe
Fully selective intramolecular ortho photocycloaddition of 4-(4-methoxyphenoxy)-3-(N3-benzoylthymin-1-yl)but-1-ene: An unprecedented benzene-thymine photocycloaddition
On irradiation of 4-(4-methoxyphenoxy)-3-(N-3-benzozylthymin-1-yl)but-1-ene 1 at 254 nm in THF a single photoadduct 2 is formed as a result of chemo-, regio- and stereo-selective intramolecular ortho photocycloaddition of the thymine double bond to the 1,2-positions of the phenyl ring.status: publishe
Ruthenium-catalysed one-pot regio- and diastereoselective synthesis of pyrrolo[1,2-a]indoles via cascade C-H functionalization/annulation
A cascade approach has been developed towards dual C-C bond formation via consecutive C-H functionalization/cyclization giving access to pyrrolo[1,2-a]indoles in a highly regio- and diastereoselective manner using catalytic [Ru(p-cymene)Cl2]2. The methodology was further expanded to attain pentacyclic structures involving manifold C-C bond creation.status: publishe
Pd/Cu-Catalyzed C–H Arylation of 1,3,4-Thiadiazoles with (Hetero)aryl Iodides, Bromides, and Triflates
The direct C–H arylation of 1,3,4-thiadiazoles
with a wide range of (hetero)Âaryl iodides, bromides, and triflates
is described using a Pd/Cu-catalyzed protocol. The methodology is
compatible with substrates possessing electron-donating or electron-withdrawing
substituents and also tolerates sterically hindered aryl halides.
The utility of the developed protocol is demonstrated by a one-pot
C–H arylation-Suzuki coupling sequence
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