Abstract:The direct conversion of 3-tri-organosilyl-or 3-organogermyl-prop-2-yn-1-ols into the corresponding imines using a solvent-free MW-assisted approach is reported. This highly effective methodology demonstrates the exploitation of α-silicon-or germanium-containing propynals generated in situ in a one-pot synthesis of ynimines. The efficient solvent-free MWmediated synthesis of the corresponding silyl-or germyl-prop-2-yn-1-als has been carried out by oxidation of the starting alcohols with manganese dioxide.
“…This procedure was developed further by Medvedeva et al, who prepared a range of imines derived from 3-silyl- and 3-germyl-prop-2-yn-1-ols using the MnO 2 methodology (Scheme ) 42 43 44 …”
Section: Top Sequences Using Nitrogen-based
Nucleophilesmentioning
confidence: 99%
“…55 Practically, this is a very straightforward process; after the completion of the reaction, the mixture is simply filtered through Celite and the solvent is removed in vacuo, giving the imines, which are usually pure by 1 and 3-germyl-prop-2-yn-1-ols using the MnO 2 methodology (Scheme 39). 57 O-Alkyl oxime ethers have also been prepared via a TOP sequence (Scheme 40). 56 This methodology was successful with a range of activated alcohols when using O-methyl and O-benzyl hydroxylamines, but little product was obtained when hydroxylamine was used as in situ trapping agent.…”
Section: Top Sequences Using Nitrogen-based Nucleophilesmentioning
"One-pot" processes in which alcohol oxidations are combined with further elaboration of the carbonyl intermediate are reviewed. Sequential processes are briefly discussed, but most attention is centered on tandem processes; that is, oxidations carried out in the presence of a nucleophilic trapping agent, rather than those in which the trapping agent is added after the oxidation is complete. As part of this Account, a comprehensive review of the discovery of tandem oxidation processes (TOP) will be given together with applications in alkene-forming reactions, cyclopropanations, and imine, oxime, amine, and heterocycle formation.
“…This procedure was developed further by Medvedeva et al, who prepared a range of imines derived from 3-silyl- and 3-germyl-prop-2-yn-1-ols using the MnO 2 methodology (Scheme ) 42 43 44 …”
Section: Top Sequences Using Nitrogen-based
Nucleophilesmentioning
confidence: 99%
“…55 Practically, this is a very straightforward process; after the completion of the reaction, the mixture is simply filtered through Celite and the solvent is removed in vacuo, giving the imines, which are usually pure by 1 and 3-germyl-prop-2-yn-1-ols using the MnO 2 methodology (Scheme 39). 57 O-Alkyl oxime ethers have also been prepared via a TOP sequence (Scheme 40). 56 This methodology was successful with a range of activated alcohols when using O-methyl and O-benzyl hydroxylamines, but little product was obtained when hydroxylamine was used as in situ trapping agent.…”
Section: Top Sequences Using Nitrogen-based Nucleophilesmentioning
"One-pot" processes in which alcohol oxidations are combined with further elaboration of the carbonyl intermediate are reviewed. Sequential processes are briefly discussed, but most attention is centered on tandem processes; that is, oxidations carried out in the presence of a nucleophilic trapping agent, rather than those in which the trapping agent is added after the oxidation is complete. As part of this Account, a comprehensive review of the discovery of tandem oxidation processes (TOP) will be given together with applications in alkene-forming reactions, cyclopropanations, and imine, oxime, amine, and heterocycle formation.
A general, green, and scalable synthesis of the useful imines and a,b-unsaturated imines is successfully achieved by a low-loading and powerful, mild and efficient copper-catalyzed aerobic oxidative reaction of alcohols and amines in the open air at room temperature under base-and dehydrating reagent-free conditions. This practical reaction can use air as the economic and green oxidant, tolerates a wide range of substrates, can afford high yields of the target imines on a large scale, and produces water as the only by-product, and thus being the best imination method as yet using alcohols and amines directly.
In line with a recent study of the pharmacological potential of bioinspired synthetic acetylenic lipids, after identification of the terminal dialkynylcarbinol (DAC) and butadiynyl alkynylcarbinol (BAC) moieties as functional antitumor pharmacophoric units, this work specifically addresses the issue of carbon backbone length. A systematic variation of the aliphatic chain length was thus carried out in both the DAC and BAC series. The critical impact of the length of the lipidic skeleton was first confirmed in the racemic series, with the highest cytotoxic activity observed for C to C backbones. Enantiomerically enriched samples were prepared by asymmetric synthesis of the optimal C DAC and C BAC derivatives. Samples with upgraded enantiomeric purity were alternatively produced by enzymatic kinetic resolution. Eutomers possessing the S configuration displayed cytotoxicity IC values as low as 15 nm against HCT116 cancer cells, the highest level of activity reached to date in this series.
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