- Double hydroacylation reactions of acyclic and cyclic α,β- unsaturated aldehydes
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Double or quits? double hydroacylation reactions of acyclic and cyclic α,β-unsaturated aldehydes with olefins afford ketone and diketone products, respectively. Enantiomers are formed whose absolute configurations are controlled by the order of alkene addition.
- Cha, Kyung-Mi,Lee, Hyejeong,Park, Jung-Woo,Lee, Yura,Jo, Eun-Ae,Jun, Chul-Ho
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supporting information; experimental part
p. 1926 - 1930
(2011/10/17)
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- Reactions at interfaces: Oxygenation of n-butyl ligands anchored on silica surfaces with methyl(trifluoromethyl)dioxirane
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The oxygenation of n-butyl and n-butoxy chains bonded to silica with methyl(trifluoromethyl)dioxirane (1) revealed the ability of the silica matrix to release electron density toward the reacting C2-H σ-bond through the Si-C1 and Si-O1 σ-bonds connecting the alkyl chain to the surface (silicon β-effect). The silica surface impedes neither the alkyl chain adopting the conformation required for the silicon β-effect nor dioxirane 1 approaching the reactive C2 methylene group. Reaction regioselectivity is insensitive to changes in the solvation of the reacting system, the location of organic ligands on the silica surface, and the H-bonding character of the silica surface. Reaction rates are faster for those organic ligands either within the silica pores or bonded to hydrophilic silica surfaces, which evidence the enhanced molecular dynamics of confined dioxirane 1 and the impact of surface phenomena on the reaction kinetics. The oxygenation of n-butyl and n-butoxy chains carrying trimethylsilyl, trimethoxysilyl, and tert-butyl groups with dioxirane 1 under homogeneous conditions confirms the electronic effects of the silyl substituents and the consequences of steric hindrance on the reaction rate and regioselectivity. Orthosilicic acid esters react preferentially at the methylene group adjacent to the oxygen atom in clear contrast with the reactivity of the carboxylic or sulfonic acid alkyl esters, which efficiently protect this position toward oxidation with 1 (Figure presented).
- Mello, Rossella,Martinez-Ferrer, Jaime,Alcalde-Aragones, Ana,Varea, Teresa,Acerete, Rafael,Gonzalez-Nunez, Maria Elena,Asensio, Gregorio
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experimental part
p. 10129 - 10139
(2012/02/14)
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- Tandem catalytic triple-bond cleavage of alkyne in association with aldehyde, alkene, and water
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In this tandem reaction the carbon-carbon triple bond of an alkyne is catalytically cleaved in association with aldehyde, al-kene, and H2O under catalyst mixtures of Rh(I), 2-amino-3-picoline, primary amine, and acid. The reaction starts with chelation-assisted hydroacylation of the alkyne with an aldehyde. The retro-Mannich-type fragmentation of the resulting ,α,β-unsaturated ketimine by an amine and acid affords a ketimine and an aldimine, which is trapped by an alkene and give ketones after hydrolysis. Georg Thieme Verlag Stuttgart.
- Cha, Kyung-Mi,Jo, Eun-Ae,Jun, Chul-Ho
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scheme or table
p. 2939 - 2942
(2010/01/21)
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- Trialkylborane as an Initiator and Terminator of Free Radical Reactions. Facile Routes to Boron Enolates via α-Carbonyl Radicals and Aldol Reaction of Boron Enolates
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A variety of trialkylborane-induced reactions were examined for the preparation of the α-carbonyl radicals: (1) addition of alkyl radical to methyl vinyl ketone, (2) reduction of α-halo ketone, and (3) intramolecular radical addition to α,β-unsaturated carbonyl moiety.Trialkylborane reacted with α-carbonyl radicals to give boron enolates.The resulting boron enolates were efficiently trapped by carbonyl compounds to give β-hydroxy ketones in good yields.
- Nozaki, Kyoko,Oshima, Koichiro,Utimoto, Kiitiro
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p. 403 - 409
(2007/10/02)
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- FACILE ROUTES TO BORON ENOLATES. Et3B-MEDIATED REFORMATSKY TYPE REACTION AND THREE COMPONENTS COUPLING REACTION OF ALKYL IODIDES, METHYL VINYL KETONE, AND CARBONYL COMPOUNDS
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Reaction of α-bromoketones with Ph3SnH in the presence of Et3B provides boron enolates which react with carbonyl compounds to give β-hydroxyketones in good yields.Et3B-induced Reformatsky type reaction of α-iodoketones with an aldehyde or ketone proceeds without Ph3SnH.
- Nozaki, Kyoko,Oshima, Koichiro,Utimoto, Kiitiro
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p. 1041 - 1044
(2007/10/02)
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- A STABLE 1:1 LITHIUM ACYLCYANOCUPRATE. DEPENDENCE OF THE STABILITY OF ACYLCYANOCUPRATES ON THE NATURE OF THE ALKYL SUBSTITUENT.
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Acylcuprates obtained by carbonylation of R(CN)CuLi cuprates (R=t-Bu, sec-Bu) at low temperature are effective in the direct nucleophilic 1,4-acylation of α,β-unsaturated ketones and aldehydes.The R=t-Bu reagent is sufficiently stable so that it can be us
- Seyfert, Dietmar,Hui, Richard C.
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p. 1473 - 1476
(2007/10/02)
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- PHOTO-OXIDATION OF ALKANES BY METAL OXIDE SEMICONDUCTORS
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The partial conversion of alkanes to the corresponding ketones has been achieved by irradiation of a suspension of semiconductor powder in oxygen-saturated alkanes.The reactivity of thermally and chemicallydoped semiconductor and the effect of chemisorbed water have also been studied.
- Giannotti, C.,Greneur, S. Le,Watts, O.
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p. 5071 - 5072
(2007/10/02)
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