The direct functionalization of Si-H bonds by the nitrene insertion methodology is described. A copper(I) complex bearing a trispyrazolylborate ligand catalyzes the transfer of a nitrene group from PhI═NTs to the Si-H bond of silanes, disilanes, and siloxanes, leading to the exclusive formation of Si-NH moieties in the first example of this transformation. The process tolerates other functionalities in the substrate such as several C-H bonds and alkyne and alkene moieties directly bonded to the silicon center. Density functional theory (DFT) calculations provide a mechanistic interpretation consisting of a Si-H homolytic cleavage and subsequent rebound to the Si-centered radical.
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http://dx.doi.org/10.1021/jacs.2c03739 | DOI Listing |
Chem Asian J
December 2024
National Institute of Pharmaceutical Education and Research, Medicinal Chemistry, Sector 67, 160062, S. A. S. Nagar, INDIA.
Ru(II)-Catalyzed "On Water" direct aryl C(sp2)-H amidation of 2-arylbenzo[d]-thiazole/oxazole with acyl azide is reported under silver-free condition. Deuterium scrambling experiments suggested reversible C-H activation catalyzed by active cationic ruthenium species. The organic solvents such as DCE, DMF, DMSO, MeCN, dioxane, and PhMe were not conducive for the C-H amidation except for PhCl in which case, however, inferior yield (31%) was obtained.
View Article and Find Full Text PDFOrg Lett
December 2024
College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang, China.
In this work, the annulation of acyl nitrene with alkynes is reported under photoredox/iron dual-catalysis for the synthesis of a series of isoquninalin-2-ones. The reaction is featured with a high reaction regioselectivity and good reaction generality. In particular, the resulting isoquinalin-2-ones could be structurally elaborated into several biologically interesting scaffolds.
View Article and Find Full Text PDFChem Rec
December 2024
Department of Pharmaceutical Technology (Process Chemistry), National Institute of Pharmaceutical Education and Research, Sector-67, S. A. S., 160062, Nagar, Punjab, India.
Metal-nitrenes are valuable reactive intermediates for synthesis and are widely used to construct biologically relevant scaffolds, complexes and functionalized molecules. The ring expansion of cyclic molecules via single-nitrogen-atom insertion via nitrene or metal-nitrenoid intermediates has emerged as a promising modern strategy for driving advantageous nitrogen-rich compound synthesis. In recent years, the catalytic insertion of a single nitrogen atom into carbocycles, leading to N-heterocycles, has become an important focus of modern synthetic approaches with applications in medicinal chemistry, materials science, and industry.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
α-Amino esters are precursors to noncanonical amino acids used in developing small-molecule therapeutics, biologics, and tools in chemical biology. α-C-H amination of abundant and inexpensive carboxylic acid esters through nitrene transfer presents a direct approach to α-amino esters. Methods for nitrene-mediated amination of the protic α-C-H bonds in carboxylic acid esters, however, are underdeveloped.
View Article and Find Full Text PDFOrg Lett
October 2024
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany.
A straightforward and general strategy for the catalytic asymmetric synthesis of β-tryptophans by carboxylic-acid-directed intermolecular C-H amination has been developed. The iron-catalyzed C-H amination of 3-indolepropionic acids with BocNHOMs (Boc, -butyloxycarbonyl; OMs, methylsulfonate) in the presence of the base piperidine provides N-Boc-protected β-tryptophans in a single step with high enantiomeric excess (ee) of up to >99%. Mechanistic experiments and density functional theory calculations support a mechanism through carboxylate-directed iron-mediated C(sp)-H nitrene insertion.
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