The mechanism and the origins of the stereocontrol observed in the reaction between differently substituted alkenes and stable (phosphino)(silyl)carbenes giving cyclopropanes have been studied computationally. These cyclopropanation reactions proceed via asynchronous concerted mechanisms involving early transition structures with a significant charge transfer from the carbene to the alkene moiety. The geometric features of these transition structures preclude a significant overlap between the orbitals required for secondary orbital interactions between the reactants. The stereoselectivity observed experimentally stems from favorable electrostatic and steric interactions between the reactants leading to the stereoisomers in which the phosphanyl and carbonyl or aryl groups are cis to each other.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jo061662v | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Computational Study on the Dynamics of a Bis(benzoxazole)-Based Overcrowded Alkene.
J Phys Chem A
January 2025
Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, Uppsala 751 20, Sweden.
Understanding and controlling molecular motions is of pivotal importance for designing molecular machinery and functional molecular systems, capable of performing complex tasks. Herein, we report a comprehensive theoretical study to elucidate the dynamic behavior of a bis(benzoxazole)-based overcrowded alkene displaying several coupled and uncoupled molecular motions. The benzoxazole moieties give rise to 4 different stable conformers that interconvert through single-bond rotations.
View Article and Find Full Text PDFRecyclable and air-stable colloidal manganese nanoparticles catalyzed hydrosilylation of alkenes with tertiary silane.
RSC Adv
January 2025
Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials, and Bioengineering, Kansai University Suita Osaka 564-8680 Japan
We synthesized ,-dimethylformamide (DMF)-stabilized manganese nanoparticles (Mn NPs) in a one-step process under air using manganese(ii) chloride as the precursor. The Mn NPs were characterized in terms of particle size, oxidation state, and local structure using annular dark-field scanning transmission electron microscopy (ADF-STEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). The results indicate that Mn NPs are divalent nanosized particles with Mn-O bonds.
View Article and Find Full Text PDFStudy protocol: multi-centre, randomised controlled clinical trial exploring stromal targeting in locally advanced pancreatic cancer; STARPAC2.
BMC Cancer
January 2025
Barts Cancer Institute and Wolfson Institute of Public Health, Mary University of London, John Vane Science Centre, Charterhouse Square, London, Queen, EC1M 6BQ, UK.
Background: Pancreatic cancer (PDAC: pancreatic ductal adenocarcinoma, the commonest form), a lethal disease, is best treated with surgical excision but is feasible in less than a fifth of patients. Around a third of patients presentlocally advanced, inoperable, non-metastatic (laPDAC), whose stadrd of care is palliative chemotherapy; a small minority are down-sized sufficiently to enable surgical excision. We propose a phase II clinical trial to test whether a combination of standard chemotherapy (gemcitabine & nab-Paclitaxel: GEM-NABP) and repurposing All Trans Retinoic Acid (ATRA) to target the stroma may extend progression-free survival and enable successful surgical resection for patients with laPDAC, since data from phase IB clinical trial demonstrate safety of GEM-NABP-ATRA combination to patients with advanced PDAC with potential therapeutic benefit.
View Article and Find Full Text PDFPhotoredox-Enabled Direct and Three-Component Difluoroalkylative Modification of -Aryl Glycinates.
Org Lett
January 2025
Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, China.
A Cu(I) photoredox-enabled reaction that selectively incorporates a difluoroalkyl group into -aryl glycine derivatives has been established. Using a bench-stable [PhPCFH]Br salt, the -CFH group could be installed either directly on the α-carbon of the glycine backbone or in a three-component fashion using an alkene as a bridge. A series of glycine derivatives have been evaluated, providing access to diverse unnatural amino esters and dipeptides with a -CHF unit.
View Article and Find Full Text PDFEasily Accessible and Solution-Stable Ni(0) Precatalysts for High-Throughput Experimentation.
Chemistry
January 2025
University of Victoria, Chemistry, 3800 Finnerty Rd, V8P 5C2, Victoria, CANADA.
We report the synthesis, characterization, and catalytic applications of N,N'-diaryl diazabutadiene (DAB) Ni(0) complexes stabilized by alkene ligands. These complexes are soluble and stable in several organic solvents, making them ideal candidates for in situ catalyst formation during high-throughput experimentation (HTE). We used HTE to evaluate these Ni(0) precatalysts in a variety of Suzuki and C-N coupling reactions, and they were found to have equal or better performance than the still-standard Ni(0) source, Ni(COD)2.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!