Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Enantioselective, Visible Light Mediated Aza Paterno-Buchi Reactions of Quinoxalinones.

ABSTRACT: 3-Substituted quinoxalin-2(1H)-ones and various aryl-substituted or tethered olefins underwent an enantioselective, inter- or intramolecular aza Paternò-Büchi reaction upon irradiation at ?=420?nm in the presence of a chiral sensitizer (10?mol?%). For the intermolecular reaction with 1-arylethenes as olefin components, the scope of the reaction was studied (14 examples, 50-99?% yield, 86-98?% ee). The absolute and relative configuration of the products were elucidated by single-crystal X-ray crystallography. The reaction is suggested to occur by triplet energy transfer in a hydrogen-bonded 1:1 complex between the imine substrate and the catalyst. The intramolecular cycloaddition, consecutive reactions of the product azetidines, and an alternative reaction mode of quinoxalinones were investigated in preliminary experiments.

SUBMITTER: Li X

PROVIDER: S-EPMC7898282 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Enantioselective, Visible Light Mediated Aza Paternò-Büchi Reactions of Quinoxalinones.

Li Xinyao X Großkopf Johannes J Jandl Christian C Bach Thorsten T

Angewandte Chemie (International ed. in English) 20201201 5

3-Substituted quinoxalin-2(1H)-ones and various aryl-substituted or tethered olefins underwent an enantioselective, inter- or intramolecular aza Paternò-Büchi reaction upon irradiation at λ=420 nm in the presence of a chiral sensitizer (10 mol %). For the intermolecular reaction with 1-arylethenes as olefin components, the scope of the reaction was studied (14 examples, 50-99 % yield, 86-98 % ee). The absolute and relative configuration of the products were elucidated by single-crystal X-ray cry ...[more]

PMID: 33084097

Similar Datasets

Functionalized azetidines via visible light-enabled aza Paterno-Buchi reactions.

Project description:Azetidines are four-membered nitrogen-containing heterocycles that hold great promise in current medicinal chemistry due to their desirable pharmacokinetic effects. However, a lack of efficient synthetic methods to access functionalized azetidines has hampered their incorporation into pharmaceutical lead structures. As a [2+2] cycloaddition reaction between imines and alkenes, the aza Paternò-Büchi reaction arguably represents the most direct approach to functionalized azetidines. Hampered by competing reaction paths accessible upon photochemical excitation of the substrates, the current synthetic utility of these transformations is greatly restricted. We herein report the development of a visible light-enabled aza Paternò-Büchi reaction that surmounts existing limitations and represents a mild solution for the direct formation of functionalized azetidines from imine and alkene containing precursors.

| S-EPMC6841681 | biostudies-literature

Accessing ladder-shape azetidine-fused indoline pentacycles through intermolecular regiodivergent aza-Paterno-Buchi reactions.

Project description:Small molecules with conformationally rigid, three-dimensional geometry are highly desirable in drug development, toward which a direct, simple-to-complexity synthetic logic is still of considerable challenges. Here, we report intermolecular aza-[2 + 2] photocycloaddition (the aza-Paternò-Büchi reaction) of indole that facilely assembles planar building blocks into ladder-shape azetidine-fused indoline pentacycles with contiguous quaternary carbons, divergent head-to-head/head-to-tail regioselectivity, and absolute exo stereoselectivity. These products exhibit marked three-dimensionality, many of which possess 3D score values distributed in the highest 0.5% region with reference to structures from DrugBank database. Mechanistic studies elucidated the origin of the observed regio- and stereoselectivities, which arise from distortion-controlled C-N coupling scenarios. This study expands the synthetic repertoire of energy transfer catalysis for accessing structurally intriguing architectures with high molecular complexity and underexplored topological chemical space.

| S-EPMC10873392 | biostudies-literature

A visible-light Paterno-Buchi dearomatisation process towards the construction of oxeto-indolinic polycycles.

Project description:A variety of highly functionalised N-containing polycycles (35 examples) are synthesised from simple indoles and aromatic ketones through a mild visible-light Paternò-Büchi process. Tetrahydrooxeto[2,3-b]indole scaffolds, with up to three contiguous all-substituted stereocenters, are generated in high yield (up to >98%) and excellent site- regio- and diastereocontrol (>20 : 1). The use of visible light (405 or 465 nm) ensures enhanced performances by switching off undesired photodimerisation side reactions. The reaction can be easily implemented using a microfluidic photoreactor with improved productivity (up to 0.176 mmol h-1) and generality. Mechanistic investigations revealed that two alternative reaction mechanisms can account for the excellent regio- and diastereocontrol observed.

| S-EPMC8159410 | biostudies-literature

Novel Aza-Paterno-Buchi Reaction Allows Pinpointing Carbon-Carbon Double Bonds in Unsaturated Lipids by Higher Collisional Dissociation.

Project description:The evaluation of double bond positions in fatty acyl chains has always been of great concern given their significance in the chemical and biochemical role of lipids. Despite being the foremost technique for lipidomics, it is difficult in practice to obtain identification beyond the fatty acyl level by the sole high-resolution mass spectrometry. Paternò-Büchi reactions of fatty acids (FAs) with ketones have been successfully proposed for pinpointing double bonds in FAs in combination with the collision-induced fragmentation technique. In the present paper, an aza-Paternò-Büchi (aPB) reaction of lipids with 6-azauracil (6-AU) was proposed for the first time for the determination of carbon-carbon double bonds in fatty acyl chains using higher collisional dissociation in the negative ion mode. The method was optimized using free FA and phospholipid analytical standards and compared to the standard Paternò-Büchi reaction with acetone. The introduction of the 6-AU moiety allowed enhancing the ionization efficiency of the FA precursor and diagnostic product ions, thanks to the presence of ionizable sites on the derivatizing agent. Moreover, the aPB derivatization allowed the obtention of deprotonated ions of phosphatidylcholines, thanks to an intramolecular methyl transfer from the phosphocholine polar heads during ionization. The workflow was finally applied for pinpointing carbon-carbon double bonds in 77 polar lipids from an yeast (Saccharomyces cerevisiae) extract.

| S-EPMC9523615 | biostudies-literature

Formation of macrocyclic lactones in the Paterno-Buchi dimerization reaction.

Project description:Furan-2-ylmethyl 2-oxoacetates 1a,b, in which the furan ring and the carbonyl moiety were embedded intramolecularly, were synthesized from commercially available furan-2-ylmethanol and their photochemical reaction (h? > 290 nm) was investigated. Twelve-membered macrocyclic lactones 2a,b with C(i) symmetry including two oxetane-rings, which are the Paternò-Büchi dimerization products, were isolated in ca. 20% yield. The intramolecular cyclization products, such as 3-alkoxyoxetane and 2,7-dioxabicyclo[2.2.1]hept-5-ene derivatives, were not detected in the photolysate.

| S-EPMC3063007 | biostudies-other

Enantioselective Intermolecular [2 + 2] Photocycloaddition Reactions of 2(1H)-Quinolones Induced by Visible Light Irradiation.

Project description:In the presence of a chiral thioxanthone catalyst (10 mol %) the title compounds underwent a clean intermolecular [2 + 2] photocycloaddition with electron-deficient olefins at ? = 419 nm. The reactions not only proceeded with excellent regio- and diastereoselectivity but also delivered the respective cyclobutane products with significant enantiomeric excess (up to 95% ee). Key to the success of the reactions is a two-point hydrogen bonding between quinolone and catalyst enabling efficient energy transfer and high enantioface differentiation. Preliminary work indicated that solar irradiation can be used for this process and that the substrate scope can be further expanded to isoquinolones.

| S-EPMC4929526 | biostudies-literature

Visible Light-Mediated Photochemical Reactions of 2-(2'-Alkenyloxy)cycloalk-2-enones.

Project description:The title compounds were prepared, and their reactivity was studied upon sensitized irradiation at λ = 420 nm. Thioxanthen-9-one was employed as the sensitizer at a loading of 10 mol % in small-scale reactions and of 2.5 mol % on a larger scale. Cyclohex-2-enones substituted by a 2'-propenyloxy, 2'-butenyloxy, 2'-pentenyloxy, or 2'-methyl-2'-propenyloxy group in the 2-position gave the products of an intramolecular [2 + 2] photocycloadditon. The reaction proceeded with high regioselectivity (crossed product) and perfect diastereoselectivity (nine examples, 34-99% yield). If the olefin in the tether was trisubstituted (3'-methyl-2'-butenyloxy), no cycloaddition was observed. Rather, a cyclization with subsequent hydrogen abstraction occurred (three examples, 65-86% yield). The results are consistent with a reaction course via a triplet enone intermediate and the formation of a 1,4-diradical by an initial cyclization. The analogous cyclopent-2-enones were less prone to an intramolecular reaction. Instead, decomposition or intermolecular [2 + 2] photocycloaddition reactions prevailed. In the latter event, two main products were identified (three examples, 30-43% yield), resulting either from a head-to-head [2 + 2]-photodimerization or from a twofold [2 + 2] photocycloaddition of the enone to the olefin. The latter reaction sequence generated pentacyclic products with a central [1,5]dioxocane ring. The structure assignment of the two product types was corroborated by a single-crystal X-ray analysis.

| S-EPMC7476038 | biostudies-literature

Enantioselective (formal) aza-Diels-Alder reactions with non-Danishefsky-type dienes.

Project description:Enantioselective (formal) aza-Diels-Alder reactions between acylhydrazones and non-Danishefsky-type dienes have been developed. The reactions are promoted by a simple and economical chiral silicon Lewis acid and are typically conducted at ambient temperature. Both glyoxylate- and aliphatic aldehyde-derived hydrazones may be employed, as may variously substituted dienes, leading to the synthesis of a diverse array of tetrahydropyridines with good to excellent levels of enantioselectivity.

| S-EPMC2918383 | biostudies-literature

Efficient Access to Chiral Trisubstituted Aziridines via Catalytic Enantioselective Aza-Darzens Reactions.

Project description:Herein, we report a Zn-ProPhenol catalyzed aza-Darzens reaction using chlorinated aromatic ketones as nucleophilic partners for the efficient and enantioselective construction of complex trisubstituted aziridines. The ?-chloro-?-aminoketone intermediates featuring a chlorinated tetrasubstituted stereocenter can be isolated in high yields and selectivities for further derivatization. Alternatively, they can be directly transformed to the corresponding aziridines in a one-pot fashion. Of note, the reaction can be run on gram-scale with low catalyst loading without impacting its efficiency. Moreover, this methodology was extended to ?-bromoketones which are scarcely used in enantioselective catalysis because of their sensitivity and lack of accessibility.

| S-EPMC5530870 | biostudies-literature

Visible-Light-Mediated Generation of Nitrogen-Centered Radicals: Metal-Free Hydroimination and Iminohydroxylation Cyclization Reactions.

Project description:The formation and use of iminyl radicals in novel and divergent hydroimination and iminohydroxylation cyclization reactions has been accomplished through the design of a new class of reactive O-aryl oximes. Owing to their low reduction potentials, the inexpensive organic dye eosin Y could be used as the photocatalyst of the organocatalytic hydroimination reaction. Furthermore, reaction conditions for a unique iminohydroxylation were identified; visible-light-mediated electron transfer from novel electron donor-acceptor complexes of the oximes and Et3N was proposed as a key step of this process.

| S-EPMC4648045 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

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