Browse
Submit Data
Databases
API
Help

Dataset Information

17 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Et3B-mediated two- and three-component coupling reactions via radical decarbonylation of α-alkoxyacyl tellurides: single-step construction of densely oxygenated carboskeletons.

ABSTRACT: The single-step construction of various densely oxygenated carboskeletons was achieved by radical-based two- and three-component coupling reactions of sugar derivatives, without the need for light or heat. Et3B/O2-mediated decarbonylation readily converted α-alkoxyacyl tellurides to α-alkoxy carbon radicals, which intermolecularly added to glyoxylic oxime ether or enones to provide the two-component adducts. Furthermore, the three-component adducts were produced by an intermolecular aldol reaction between the aldehyde and the boron enolates generated by capture of the two-component radical intermediates by Et3B. This powerful coupling method serves as a novel strategy for the convergent synthesis of polyol natural products.

SUBMITTER: Nagatomo M

PROVIDER: S-EPMC5763990 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Three-component coupling reactions of silylglyoxylates, alkynes, and aldehydes: a chemoselective one-step glycolate aldol construction.

Project description:A single-pot three-component coupling reaction of silylglyoxylates (1), terminal alkynes, and aldehydes in the presence of ZnI2 and Et3N is presented. The products of the reaction, densely functionalized silyl-protected glycolate aldols (2), can be converted to the corresponding acetonides (3) in a one-pot deprotection/ketalization sequence. A variety of terminal alkynes and aldehydes can be successfully employed to give a range of highly functionalized, fully protected 1,2-diols in good yields and moderate diastereoselectivities. Mechanistic experiments suggest that the zinc acetylide reacts with the silylgyloxylate (1) in a chemoselective manner. Using an unoptimized (+)-N-methylephedrine and Zn(OTf)2 system, silyl-deprotected adduct 2 was formed in 64% ee and 89:11 dr.

| S-EPMC2827871 | biostudies-literature

Pyridylphosphonium salts as alternatives to cyanopyridines in radical-radical coupling reactions.

Project description:Radical couplings of cyanopyridine radical anions represent a valuable technology for functionalizing pyridines, which are prevalent throughout pharmaceuticals, agrochemicals, and materials. Installing the cyano group, which facilitates the necessary radical anion formation and stabilization, is challenging and limits the use of this chemistry to simple cyanopyridines. We discovered that pyridylphosphonium salts, installed directly and regioselectively from C-H precursors, are useful alternatives to cyanopyridines in radical-radical coupling reactions, expanding the scope of this reaction manifold to complex pyridines. Methods for both alkylation and amination of pyridines mediated by photoredox catalysis are described. Additionally, we demonstrate late-stage functionalization of pharmaceuticals, highlighting an advantage of pyridylphosphonium salts over cyanopyridines.

| S-EPMC8356814 | biostudies-literature

Radical/Polar Annulation Reactions (RPARs) Enable the Modular Construction of Cyclopropanes.

Project description:An annulation process for the construction of 1,1-disubstituted cyclopropanes via a radical/polar crossover process is described. The cyclopropanation proceeds by the addition of a photocatalytically generated radical to a homoallylic tosylate. Reduction of the intermediate radical alkylation adduct (via single electron transfer) furnishes an anion that undergoes an intramolecular substitution. The process displays excellent functional group tolerance, characteristic of proceeding through odd-electron intermediates, and occurs under mild conditions with visible light irradiation.

| S-EPMC6218941 | biostudies-literature

Enantiospecific Trifluoromethyl-Radical-Induced Three-Component Coupling of Boronic Esters with Furans.

Project description:In the presence of trifluoromethylsulfonium reagents, boronate complexes derived from 2-lithio furan and non-racemic secondary and tertiary alkyl or aryl boronic esters undergo deborylative three-component coupling to give the corresponding 2,5-disubstituted furans with excellent levels of enantiospecificity. The process proceeds via the reaction of boronate complexes with a trifluoromethyl radical, which triggers 1,2-metallate rearrangement upon single-electron oxidation. Alternative electrophiles can also be used in place of trifluoromethylsulfonium reagents to effect similar three-component coupling reactions.

| S-EPMC5499725 | biostudies-literature

Diels-Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton.

Project description:Regioselective construction of 4,8,9-trioxygenated 2,3-dihydrobenz[f]indenones, key intermediates for the synthesis of kinamycin antibiotics, was achieved via Diels-Alder reactions (DAR) using 4,7-dioxygenated indanone-type compounds as dienophiles. Reaction of indanetrione with 1-methoxybutadiene gave a 1 : 1 mixture of undesired 4,5,9-trioxygenated 2,3-dihydrobenz[f]indenone and [4.4.3]propellane. The addition of Lewis acid did not affect the product ratio, whereas the use of the 6-bromoindanetrione exclusively afforded the latter propellane. On the other hand, DAR of benzyne derived from bromoindan and furan gave 5,8-epoxy-2,3-dihydrobenz[f]indene, which was subjected to acid-induced ring opening to give 2,3-dihydrobenz[f]indenone with undesired 4,5,9-trioxy functions.

| S-EPMC2486486 | biostudies-literature

Modular, Catalytic Enantioselective Construction of Quaternary Carbon Stereocenters by Sequential Cross-Coupling Reactions.

Project description:The catalytic Suzuki-Miyaura cross-coupling with chiral γ,γ-disubstituted allylboronates in the presence of RuPhos ligand occurs with high regioselectivity and enantiospecificity, furnishing nonracemic compounds with quaternary centers. Mechanistic experiments suggest that the reaction occurs by transmetalation with allyl migration, followed by rapid reductive elimination.

| S-EPMC5510877 | biostudies-literature

Construction of sterically congested oxindole derivatives <i>via</i> visible-light-induced radical-coupling.

Project description:The oxindole scaffold represents an important structural feature in many natural products and pharmaceutically relevant molecules. Herein, we report a visible-light-induced modular methodology for the synthesis of complex 3,3'-disubstituted oxindole derivatives. A library of valuable fluoroalkyl-containing highly sterically congested oxindole derivatives can be synthesized by a catalytic three-component radical coupling reaction under mild conditions (metal & photocatalyst free, >80 examples). This strategy shows high functional group tolerance and broad substrate compatibility (including a wide variety of terminal or non-terminal alkenes, conjugated dienes and enynes, and a broad array of polyfluoroalkyl iodide and oxindoles), which enables modular modification of complex drug-like compounds in one chemical step. The success of solar-driven transformation, large-scale synthesis, and the late-stage functionalization of bioactive molecules, as well as promising tumor-suppressing biological activities, highlights the potential for practical applications of this strategy. Mechanistic investigations, including a series of control experiments, UV-vis spectroscopy and DFT calculations, suggest that the reaction underwent a sequential two-step radical-coupling process and the photosensitive perfluoroalkyl benzyl iodides are key intermediates in the transformation.

| S-EPMC8635216 | biostudies-literature

Construction of cyclopentanol derivatives via three-component coupling of silyl glyoxylates, acetylides, and nitroalkenes.

Project description:The three-component coupling of Mg acetylides, silyl glyoxylates, and nitroalkenes results in a highly diastereoselective Kuwajima-Reich/vinylogous Michael cascade that provides tetrasubstituted silyloxyallene products. The regio- and diastereoselectivity were studied using DFT calculations. These silyloxyallenes were converted to cyclopentenols and cyclopentitols via a unique Lewis acid assisted Henry cyclization. The alkene functionality present in the cyclopentanol products can be elaborated using diastereoselective ketohydroxylation reactions.

| S-EPMC3265386 | biostudies-literature

Adiabatic elimination-based coupling control in densely packed subwavelength waveguides.

Project description:The ability to control light propagation in photonic integrated circuits is at the foundation of modern light-based communication. However, the inherent crosstalk in densely packed waveguides and the lack of robust control of the coupling are a major roadblock toward ultra-high density photonic integrated circuits. As a result, the diffraction limit is often considered as the lower bound for ultra-dense silicon photonics circuits. Here we experimentally demonstrate an active control of the coupling between two closely packed waveguides via the interaction with a decoupled waveguide. This control scheme is analogous to the adiabatic elimination, a well-known procedure in atomic physics. This approach offers an attractive solution for ultra-dense integrated nanophotonics for light-based communications and integrated quantum computing.

| S-EPMC4491806 | biostudies-literature

New reactions of 2-methylenetetrahydropyrans. A three component coupling protocol for the synthesis of tetrahydropyranyl ketides.

Project description:Three component coupling of a 2-methylenetetrahydropyran, an activated aldehyde or ketone and a secondary nucleophile provides an efficient preparation of tetrahydropyranyl ketides, a unit common to many complex natural products.

| S-EPMC4335680 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data