- A Ball-Milling-Enabled Reformatsky Reaction
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An operationally simple one-jar one-step mechanochemical Reformatsky reaction using in situ generated organozinc intermediates under neat grinding conditions has been developed. Notable features of this reaction protocol are that it requires no solvent, no inert gases, and no pre-activation of the bulk zinc source. The developed process is demonstrated to have good substrate scope (39–82 % yield) and is effective irrespective of the initial morphology of the zinc source.
- Cao, Qun,Stark, Roderick T.,Fallis, Ian A.,Browne, Duncan L.
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p. 2554 - 2557
(2019/06/17)
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- Allylation of carbonyl compounds mediated by nanometer-sized bismuth in water
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It is found that nanometer-sized bismuth mediates the allylation of carbonyl compounds in water to afford the corresponding homoallylic alcohol in high yields. Nanometer-sized bismuth is much more effective than regular bismuth powder in this reaction.
- Xu, Xiaolan,Zha, Zhenggen,Miao, Qian,Wang, Zhiyong
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p. 1171 - 1174
(2007/10/03)
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- Indium trichloride-promoted tin-mediated carbonyl allylation in water: High simple diastereo- and diastereofacial selectivity
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Tin-mediated additions of allylic bromides to aldehydes and aldoses leads to adduct with high diastereo- and diastereofacial selectivity in the presence of indium trichloride in water.
- Li, Xu-Ran,Loh, Teck-Peng
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p. 1535 - 1538
(2007/10/03)
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- One-pot Preparation of β-Hydroxy Esters Catalysed by a Bis(cyclopentadienyl)titanium(IV) Dichloride-Zinc System
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The reaction of α-haloesters with carbonyl compounds catalysed by Cp2TiCl2(cat.)-Zn gives β-hydroxy esters.
- Ding, Yu,Zhao, Gang
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p. 941 - 942
(2007/10/02)
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- Anion-Catalyzed Reactions of Silyl Ester Polyenolates with Electrophiles
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The stereochemical assignments for the trimethylsilyl ester polyenolates 1, 2, and 3 have been made.Unlike simple silyl ketene acetals, 1, 2, and 3 are obtained predominantly as the thermodynamic Z isomers.Bifluoride-catalyzed equilibration studies showed the equilibrium compositions of 1, 2, and 3 to be 89percent Z, 67percent Z, and 95percent 1-Z,3-E, respectively.The regiochemistry of the bifluoride-catalyzed Reformatsky-type reaction of benzaldehyde with 1, 2, and 4 was determined.Regiochemical control of the condensation of 1 with benzaldehyde by reaction temperature was demonstrated, with 95percent α reaction at -95 deg C and 99percent γ-reaction at +34 deg C.Mechanism studies are consistent with a dissociative process in which a dienolate reacts with benzaldehyde at the α position to give the kinetic-controlled product, and as the reaction temperature increases, increasing amounts of the thermodynamic γ product are formed.A nondissociative cyclic process leading to α product may occur at low temperatures.The naked ester dienolate prepared by reaction of 1 with TASF and removal of the resulting fluorotrimethylsilane was alkylated by benzyl bromide exclusively at the α position at -100 deg C.The bifluoride-catalyzed reverse reaction of 1 with benzaldehyde is much slower than the processes that determine the regiochemistry in the forward reaction.
- Hertler, Walter R.,Reddy, Gade S.,Sogah, Dotsevi Y.
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p. 3532 - 3539
(2007/10/02)
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- THE REACTION OF α-STANNYLMETHYLLITHIUM WITH ESTERS
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Ketonic compounds were prepared from esters using α-stannylmethyllithium as the reagent.
- Sato, Tadashi,Matsuoka, Hiroharu,Igarashi, Tsutomu,Murayama, Eigoro
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p. 4339 - 4342
(2007/10/02)
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- Regioselectivity in the Reformatsky Reaction of 4-Bromocrotonate. Role of the Catalyst and the Solvent in the Normal vs. Abnormal Modes of Addition to Carbonyl Substrates
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The regioselectivity of addition of the organozinc reagent derived from ethyl 4-bromocrotonate to 10 carbonyl substrates was found to be dependent on the polarity of solvents and the hardness of metal catalysts.
- Rice, Leonard E.,Boston, M.Craig,Finklea, Harry O.,Suder, Billy Jo,Frazier, James O.,Hudlicky, Tomas
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p. 1845 - 1848
(2007/10/02)
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