Nickel-mediated decarbonylative cross-coupling of phthalimides with in situ generated diorganozinc reagents
The nickel-mediated cross-coupling of phthalimides with diorganozinc reagents proceeds via a decarbonylative process to produce ortho-substituted benzamides in high yields. In addition to tolerating diverse phthalimide functionality, including alkyl, aryl
Havlik, Sarah E.,Simmons, Jessica M.,Winton, Valerie J.,Johnson, Jeffrey B.
We describe a one-pot, simultaneous Suzuki- Miyaura cross-coupling of two different aryl boronic acids with symmetrical dibromo aryl and heterocyclic substrates to give as major products the unsymmetrical disubstituted tri(hetero)aryl derivatives. Yields
Beaumard, Floriane,Dauban, Philippe,Dodd, Robert H.
supporting information; experimental part
p. 1801 - 1804
(2009/08/15)
Thieme journal awardees - Where are they now? on cobalt-catalyzed biaryl coupling reactions
An operationally simple biaryl coupling reaction has been developed. The underlying domino process involves in situ Grignard formation from aryl bromides and subsequent homocoupling with catalytic CoCl2 and 1 bar synthetic air as terminal oxidant. Georg Thieme Verlag Stuttgart.
Mayer, Matthias,Czaplik, Waldemar Maximilian,Jacobi Von Wangelin, Axel
experimental part
p. 2919 - 2923
(2010/01/21)
Mechanistic study of a Pd/C-catalyzed reduction of aryl sulfonates using the Mg-MeOH-NH4OAc system
A method for the deoxygenation of phenolic hydroxy groups via aryl triflates or mesylates has been established by using a combination of Pd/ C-Mg-MeOH. The addition of NH4OAc to the system markedly accelerated the reaction rate and expanded the scope of the reaction. Mechanistic studies suggested that a single-electron transfer process from the Pd0 center to the benzene ring is involved in the reduction of aryl sulfonates and that NH4OAc works as a solubilization re agent of the Mg salt and as an accelerator of the electron transfer, thus enhancing the reaction process. Our method was also applicable to the regioselective deuteration of benzene derivatives with CH3OD as the solvent and deuterium source: the original hydroxy group could be efficiently replaced with a deuterium atom.
Pd/C-catalyzed deoxygenation of phenol derivatives using mg metal and MeOH in the presence of NH4OAc
A Pd/C-catalyzed deoxygenation method of phenolic hydroxyl groups via aryl triflates or mesylates using Mg metal in MeOH at room temperature was developed. The addition of NH4OAc dramatically affects the reactivity and reaction rate. This method is particularly attractive to provide an environmentally benign and widely applicable removal method of phenolic alcohols under quite mild reaction conditions.
On the optical activity of the 3-aryl-4-hydroxycoumarin isolated from Millettia griffoniana: Molecular modelling and total synthesis
Semi-empirical calculations on 4-hydroxy-3-(3′,4′-methylenedioxyphenyl)-5,6, 7-trimethoxycoumarin, a natural product recently isolated from Millettia griffoniana, show low rotational barriers for the C(3)-C(1′) bond (19.9 kJ mol-1) and for the
Combes,Finet,Siri
p. 38 - 44
(2007/10/03)
Novel syntheses of cis and trans isomers of combretastatin A-4
A high-yielding, two-step stereoselective synthesis of the anticancer drug (Z)-combretastatin A-4 (1) has been devised. The method uses the Perkin condensation of 3,4,5-trimethoxyphenylacetic acid and 3-hydroxy-4-methoxybenzaldehyde followed by decarboxylation of the cinnamic acid intermediate using copper and quinoline. The iodine-catalyzed isomerization of the Z isomer 1 results in complete conversion to the E isomer. The Suzuki cross-coupling of an aryl boronic acid and vinyl bromide has also been successfully employed to produce both Z and E isomers of combretastatin A-4 stereoselectively. Both methods are far superior to the current five-step Wittig synthesis in which both isomers are produced nonstereoselectively.
Gaukroger, Keira,Hadfield, John A.,Hepworth, Lucy A.,Lawrence, Nicholas J.,McGown, Alan T.
p. 8135 - 8138
(2007/10/03)
Constituents of Eupomatia Species. VII. Dienone-Phenol and Dienol-Benzene Rearrangements in the Eupodienone-1 Series
Rearrangement of eupodienone-1 and derivatives, including certain dienols, under a variety of acidic conditions produced dibenzocyclooctene derivatives.Spectroscopic evidence and chemical degradation showed that in the rearrangements alkyl rather than aryl group migration had occured.The stereochemistry of the products is discussed.
Bowden, Bruce F.,Read, Roger W.,Taylor, Walter C.
p. 799 - 817
(2007/10/02)
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