29917-69-9Relevant academic research and scientific papers
Photoredox-Catalyzed Dehydrogenative Csp3-Csp2Cross-Coupling of Alkylarenes to Aldehydes in Flow
Griffiths, Oliver M.,Esteves, Henrique A.,Chen, Yiding,Sowa, Karin,May, Oliver S.,Morse, Peter,Blakemore, David C.,Ley, Steven V.
, p. 13559 - 13571 (2021/10/01)
Executing photoredox reactions in flow offers solutions to frequently encountered issues regarding reproducibility, reaction time, and scale-up. Here, we report the transfer of a photoredox-catalyzed benzylic coupling of alkylarenes to aldehydes to a flow chemistry setting leading to improvements in terms of higher concentration, shorter residence times, better yields, ease of catalyst preparation, and enhanced substrate scope. Its applicability has been demonstrated by a multi-gram-scale reaction using high-power light-emitting diodes (LEDs), late-stage functionalization of selected active pharmaceutical ingredients (APIs), and also a photocatalyst recycling method.
Organocatalytic Selective [3 + 2] Cycloadditions: Synthesis of Functionalized 5-Arylthiomethyl-1,2,3-triazoles and 4-Arylthio-1,2,3-triazoles
Reddy, G. Surendra,Reddy, L. Mallikarjuna,Kumar, A. Suresh,Ramachary, Dhevalapally B.
, p. 15488 - 15501 (2020/11/30)
An organocatalytic azide-ketone [3 + 2] cycloaddition (OrgAKC) of a variety of 1-aryl-3-(arylthio)propan-2-ones and 1-alkyl-3-(arylthio)propan-2-ones with different aryl/vinyl/alkyl azides is reported under ambient conditions to furnish the medicinally important 1,4-disubstituted-5-arylthiomethyl-1,2,3-triazoles and 1,5-disubstituted-4-arylthio-1,2,3-triazoles, respectively, in a regioselective manner with high yields/rates. With controlled and online NMR experiments, we proved that the reaction path is following the organocatalytic enolization through selective deprotonation followed by a [1,3]-H shift. Surprisingly, the [3 + 2] cycloaddition of aryl/vinyl/alkyl azides with the in situ-generated equilibrated thermodynamic ? kinetic enolates furnished the highly regioselective functionally rich 1,2,3-triazoles by discriminating their reactivities. This is the first report on the investigation of a selective OrgAKC with the regiomers of enolates generated in situ from the unsymmetrical carbonyl compounds. The reaction sustainability is explained with a few controlled experiments, mechanistic studies, and applications.
Palladium-catalyzed mono-α-arylation of acetone with aryl imidazolylsulfonates
Ackermann, Lutz,Mehta, Vaibhav P.
supporting information; experimental part, p. 10230 - 10233 (2012/09/22)
Set the ace(tone): A palladium catalyst derived from the bidentate XantPhos ligand and Pd(OAc)2 has enabled broadly applicable mono-α-arylations of acetone to be performed with air- and moisture-stable aryl imidazolylsulfonates as most user-friendly electrophiles (see scheme). Copyright
Unsurpassed cage effect for the photolysis of dibenzyl ketones in water-soluble dendrimers
Yuan, Zhao,Chen, Jinping,Zeng, Yi,Li, Ying-Ying,Han, Yongbin,Li, Yi
experimental part, p. 6256 - 6264 (2011/10/09)
Amphiphilic water-soluble poly(alkyl aryl ether) dendrimers Gn (n = 1-3) with charge-neutral tetraethylene glycol monomethyl ethers at their periphery were synthesized as microreactors to control the photochemical reactions of dibenzyl ketone derivatives in aqueous solutions. Photophysical studies demonstrated that Gn can encapsulate organic molecules and provide a hydrophobic microenvironment. The product distribution of photolysis of dibenzyl ketone derivatives can be successfully controlled by encapsulating the substrates within dendrimers, and an unsurpassed cage effect of 1.00 is reached in high generation dendrimers, revealing that a thick and compact "shell" was formed at the periphery of the dendrimers. The cage effect is also significantly influenced by the substituent at the para-position of the guest molecules. The higher generation dendrimers exhibit a better confined microenvironment and the aggregates possess more compact cavities to "lock" the guests than the corresponding unimolecular dendrimers. After photolysis, the separation of products can be easily achieved by extracting from the dendrimer solutions and the dendrimers are simply recovered and reused.
Photolysis of 5,5-dibenzyl-Δ3-1,3,4-oxadiaiolines
Warkentin, John,Woollard, John McK.R.
, p. 289 - 307 (2007/10/03)
Photolysis of dibenzyl-Δ3-1,3,4-oxadiazolines (3) in the presence of dimethyl acetylenedicarboxylate (DMAD) gives only modest yields of the expected symmetrical 3,3-dibenzylcyclopropenes (4), but these are accompanied by more than six by-products, including unsymmetrical cyclopropenes, methylenecyclopropanes, and various pyrazoles. The origin of this array of products can be explained by a series of steps starting with photolysis of 3 to form a diazoalkane that undergoes 1,3-dipolar cycloaddition to DMAD, generating a 3H-pyrazole as initial product. The latter is further photolyzed to a symmetrical cyclopropene in competition with benzyl group migration by thermal 1,5-sigmatropic or ion-pair rearrangement to afford a 4H-pyrazole. The 4H-pyrazole in turn undergoes photolysis to an unsymmetrical cyclopropene, which rearranges to a methylenecyclopropane. The 4H-pyrazole also undergoes autoxidation, in the presence of air, to afford a benzoyl-4H-pyrazole. Additionally, in competition with rearrangement, the various pyrazoles lose a benzyl group or a methoxycarbonyl group to afford pyrazoles with one less substituent.
