Topic
Methyl vinyl ketone
About: Methyl vinyl ketone is a research topic. Over the lifetime, 1510 publications have been published within this topic receiving 26839 citations. The topic is also known as: 3-buten-2-one & gamma-oxo-alpha-butylene.
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TL;DR: It has been found that the chiral amines catalyze the formation of optically active substituted 5-keto aldehydes in good yields and enantioselectivities, using aldeHydes and, e.g., methyl vinyl ketone as starting compounds.
Abstract: Chiral amines such as (S)-2-[bis(3,5-dimethylphenyl)methyl]pyrrolidine and the C2-symmetric (2S,5S)-2,5-diphenylpyrrolidine can catalyze the direct enantioselective Michael addition of simple aldehydes to vinyl ketones. The conditions for this organocatalytic reaction have been optimized and it has been found that the chiral amines catalyze the formation of optically active substituted 5-keto aldehydes in good yields and enantioselectivities, using aldehydes and, e.g., methyl vinyl ketone as starting compounds. Taking into account that the chiral amine can activate the aldehyde and/or the enone, the mechanism for the reaction has been investigated. On the basis of intermediate synthesis, nonlinear effect, and theoretical investigations, the mechanism for the catalytic direct enantioselective Michael addition of aldehydes to vinyl ketones is discussed.
145 citations
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TL;DR: First strong indications for the crucial role of halogen bonding in this kind of catalyses are presented, including the solvolysis of benzhydryl chloride and the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone.
Abstract: Hypervalent iodine(III) derivatives are known as versatile reagents in organic synthesis, but there is only one previous report on their use as Lewis acidic organocatalysts. Herein, we present first strong indications for the crucial role of halogen bonding in this kind of catalyses. To this end, the solvolysis of benzhydryl chloride and the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone served as benchmark reactions for halide abstraction and the activation of neutral compounds. Iodolium compounds (cyclic diaryl iodonium species) were used as activators or catalysts, and we were able to markedly reduce or completely switch off their activity by sterically blocking one or two of their electrophilic axes. Compared with previously established bidentate cationic halogen bond donors, the monodentate organoiodine derivatives used herein are at least similarly active (in the Diels-Alder reaction) or even decidedly more active (in benzhydryl chloride solvolysis).
141 citations
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TL;DR: In this article, the authors used a fast Proton Transfer Reaction Mass Spectrometry (PTR-MS) instrument for analysis of the Mediterranean holm oak (Quercus ilex L).
Abstract: Volatile organic compound (VOC) emissions of the Mediterranean holm oak (Quercus ilex L.) were investigated using a fast Proton Transfer Reaction Mass Spectrometry (PTR-MS) instrument for analysis. This technique is able to measure compounds with a proton affinity higher than water with a high time resolution of 1 s per compound. Hence nearly all VOCs can be detected on-line. We could clearly identify the emission of methanol, acetaldehyde, ethanol, acetone, acetic acid, isoprene, monoterpenes, toluene, and C10-benzenes. Some other species could be tentatively denominated. Among these are the masses 67 (cyclo pentadiene), mass 71 (tentatively attributed to methyl vinyl ketone (MVK) and metacrolein (MACR)), 73 (attributed to methyl ethyl ketone (MEK)), 85 (C6H12 or hexanol), and 95 (vinylfuran or phenol). The emissions of all these compounds (identified as well as nonidentified) together represent 99% of all masses detected and account for a carbon loss of 0.7–2.9% of the net photosynthesis. Of special interest was a change in the emission behavior under changing environmental conditions such as flooding or fast light/dark changes. Flooding of the root system caused an increase of several VOCs between 60 and 2000%, dominated by the emission of ethanol and acetaldehyde, which can be explained by the well described production of ethanol under anoxic conditions of the root system and the recently described subsequent transport and partial oxidation to acetaldehyde within the green leaves. However, ethanol emissions were dominant. Additionally, bursts of acetaldehyde with lower ethanol emission were also found under fast light/dark changes. These bursts are not understood.
141 citations
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TL;DR: In this paper, the optimal interaction energies were found to be 1.5-2.0 kcal/mol more favorable for hydrogen bonding to the oxygen or nitrogen in the transition states than for the dienophiles.
Abstract: Ab initio molecular orbital calculations reveal enhanced hydrogen bonding of a water molecule to the transition states for the Diels-Alder reactions of cyclopentadiene with methyl vinyl ketone (MVK) and acrylonitrile. The optimal interaction energies are found to be 1.5-2.0 kcal/mol more favorable for hydrogen bonding to the oxygen or nitrogen in the transition states than for the dienophiles. This support the assertion from a prior simulation study that the observed rate accelerations for Diels-Alder reactions in aqueous solution arise from this hydrogen-bonding effect in addition to a relatively constant hydrophobic term
139 citations
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TL;DR: In this paper, the reaction of α,β-unsaturated ketones with electron-rich arenes catalyzed by gold(III) chloride both, a Friedel-Crafts-type mechanism and an initial metallation, are evaluated.
Abstract: For the reaction of α,β-unsaturated ketones with electron-rich arenes catalyzed by gold(III) chloride both, a Friedel–Crafts-type mechanism and an initial metallation, are evaluated. Gold(III) chloride has proven to be an efficient catalyst under very moderate reaction conditions, however, in the case of sterically demanding products HBF4 turned out to be the superior catalyst.
139 citations