- Synthesis of pyrazolylvinyl ketones from furan derivatives
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A new protocol for the synthesis of pyrazol-5-ylvinyl ketones, e.g. pyrazole-chalcones, employing furfuryl ketones as a triketone equivalent, has been developed. The reaction occurs under mild conditions and does not require the use of expensive materials
- Sawengngen, Nattawut,Chalikidi, Petrakis N.,Araby, Sara,Hampel, Frank,Gmeiner, Peter,Serdyuk, Olga V.
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supporting information
p. 4850 - 4855
(2019/05/24)
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- Efficient Synthesis of N-Benzyloxycarbonyl-2-aminoalkanesulfonyl Chlorides with Functionalized Side Chains
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N-Benzyloxycarbonyl (Cbz)-protected 2-aminoalkanesulfonyl chlorides are useful building blocks for the synthesis of sulfonopeptides, which are receptor ligands and enzyme inhibitors, and are prepared by the coupling reaction of N-protected aminoalkanesulfonyl chlorides with amino acid or peptide esters. Various N-Cbz-protected 2-aminoalkanesulfonyl chlorides with functionalized side chains were synthesized through the radical addition of different xanthates to benzyl N-allylcarbamate and subsequent oxidative chlorination with tert-butyl hypochlorite under neutral conditions. A mechanism for the oxidative chlorination is proposed. This is a useful and convenient strategy for the synthesis of N-Cbz-protected 2-aminoalkanesulfonyl chlorides with diverse functionalized side-chains.
- Abdellaoui, Hassane,Chen, Xingpeng,Xu, Jiaxi
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p. 2250 - 2256
(2017/05/05)
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- Copper(I)-catalyzed oxidation of alkenes using molecular oxygen and hydroxylamines: Synthesis and reactivity of α-oxygenated ketones
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The copper(I)-catalyzed oxidation of alkenes with molecular oxygen and N-hydroxyphthalimide (NHPI) or N-hydroxybenzotriazole (HOBt) provided α-oxygenated ketones. The reaction proceeded under a balloon of O2 at room temperature to furnish the dioxygenated products in 50-90% yield. These compounds, particularly the HOBt derivatives, can be further functionalized with phosphorus, nitrogen, and sulfur nucleophiles to give synthetically useful products.
- Andia, Alexander A.,Miner, Matthew R.,Woerpel
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supporting information
p. 2704 - 2707
(2015/06/16)
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- A Convergent Radical Based Route to Trifluoromethyl Ketones and to α,β-Unsaturated Trifluoromethyl Ketones
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A convergent synthesis of trifluoromethyl ketones and α,β-unsaturated trifluoromethyl ketones is described, starting with aliphatic iodides and dithiocarbonates (xanthates) and exploiting both the α- and β-fragmentations of a sulfonyl radical. The transfo
- Anthore, Lucile,Zard, Samir Z.
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supporting information
p. 3058 - 3061
(2015/06/30)
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- Photochemistry of S -phenacyl xanthates
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Various synthetically readily accessible S-phenacyl xanthates are shown to undergo photoinitiated homolytic scission of the C-S bond in the primary step. The resultant fragments, phenacyl and xanthic acid radicals, recombine to form symmetrical 1,4-diketones and xanthogen disulfides, respectively, in high to moderate chemical yields in chemically inert solvents. They can also be efficiently trapped by a hydrogen-atom-donating solvent to give acetophenone and xanthic acid derivatives. The latter compound is in situ thermally converted to the corresponding alcohol in high chemical yields. S-Phenacyl xanthates could thus be utilized as synthetic precursors to the above-mentioned compounds or as photoremovable protecting groups for alcohols in which the xanthate moiety represents a photolabile linker. The photochemically released phenacyl radical fragments efficiently but reversibly add to the thiocarbonyl group of the parent xanthate molecule. The kinetics of this degenerative reversible addition-fragmentation transfer (RAFT)/macromolecular design via the interchange of xanthates (MADIX) mechanism was studied using laser flash photolysis (LFP) and density functional theory (DFT) calculations. The rate constants of the RAFT addition step, kadd ~ 7 × 108 M-1 s-1, and phenacyl radical addition to a double bond of 1,1-diphenylethylene, kadd ~ 108 M-1 s -1, in acetonitrile were experimentally determined by LFP. In addition, photoinitiation of the methyl methacrylate polymerization by S-phenacyl xanthate is demonstrated. The polydispersity index of the resulting poly(methyl methacrylate) was found to be ~1.4. We conclude that S-phenacyl xanthates can serve simultaneously as photoinitiators as well as RAFT/MADIX agents in polymerization reactions.
- Tazhe Veetil, Aneesh,Solomek, Tomas,Ngoy, Bokolombe Pitchou,Pavlikova, Nela,Heger, Dominik,Klan, Petr
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experimental part
p. 8232 - 8242
(2012/01/03)
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