- Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
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The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
- Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
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supporting information
p. 7868 - 7875
(2021/05/27)
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- Ketone Synthesis by a Nickel-Catalyzed Dehydrogenative Cross-Coupling of Primary Alcohols
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An intermolecular coupling of primary alcohols and organotriflates has been developed to provide ketones by the action of a Ni(0) catalyst. This oxidative transformation is proposed to occur by the union of three distinct catalytic cycles. Two competitive oxidation processes generate aldehyde in situ via hydrogen transfer oxidation or (pseudo)dehalogenation pathways. As aldehyde forms, a Ni-catalyzed carbonyl-Heck process enables formation of the key carbon-carbon bond. The utility of this rare alcohol to ketone transformation is demonstrated through the synthesis of diverse complex and bioactive molecules.
- Verheyen, Thomas,Van Turnhout, Lars,Vandavasi, Jaya Kishore,Isbrandt, Eric S.,De Borggraeve, Wim M.,Newman, Stephen G.
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supporting information
(2019/05/08)
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- Ketone Synthesis by a Nickel-Catalyzed Dehydrogenative Cross-Coupling of Primary Alcohols
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An intermolecular coupling of primary alcohols and organotriflates has been developed to provide ketones by the action of a Ni(0) catalyst. This oxidative transformation is proposed to occur by the union of three distinct catalytic cycles. Two competitive oxidation processes generate aldehyde in situ via hydrogen transfer oxidation or (pseudo)dehalogenation pathways. As aldehyde forms, a Ni-catalyzed carbonyl-Heck process enables formation of the key carbon-carbon bond. The utility of this rare alcohol to ketone transformation is demonstrated through the synthesis of diverse complex and bioactive molecules.
- Verheyen, Thomas,Van Turnhout, Lars,Vandavasi, Jaya Kishore,Isbrandt, Eric S.,De Borggraeve, Wim M.,Newman, Stephen G.
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supporting information
p. 6869 - 6874
(2019/05/10)
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- Green and Efficient: Iron-Catalyzed Selective Oxidation of Olefins to Carbonyls with O2
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A mild and operationally simple iron-catalyzed protocol for the selective aerobic oxidation of aromatic olefins to carbonyl compounds is described. Catalyzed by a Fe(III) species bearing a pyridine bisimidazoline ligand at 1 atm of O2, α- and β-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance, including those containing radical-sensitive groups. With α-halo-substituted styrenes, the oxidation took place with concomitant halide migration to afford α-halo acetophenones. Various observations have been made, pointing to a mechanism in which both molecular oxygen and the olefinic substrate coordinate to the iron center, leading to the formation of a dioxetane intermediate, which collapses to give the carbonyl product. (Chemical Equation).
- Gonzalez-De-Castro, Angela,Xiao, Jianliang
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supporting information
p. 8206 - 8218
(2015/07/15)
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- Structural effects on the β-scission reaction of tertiary arylcarbinyloxyl radicals. The role of α-cyclopropyl and α-cyclobutyl groups
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A product and time-resolved kinetic study on the reactivity of tertiary arylcarbinyloxyl radicals bearing α-cyclopropyl and α-cyclobutyl groups has been carried out. Both the 1-cyclopropyl-1-phenylethoxyl (1 .) and α,α-dicyclopropylphenylmethoxyl (2.) radicals undergo β-scission to give cyclopropyl phenyl ketone as the major or exclusive product with rate constants higher than that measured for the cumyloxyl radical. It is proposed that in the transition state for β-scission of 1. and 2., formation of the C=O double bond is assisted by overlap with the C-C bonding orbitals of the cyclopropane ring. With tertiary arylcarbinyloxyl radicals bearing α-cyclobutyl groups such as the 1-cyclobutyl-1-phenylethoxyl (4.) and 1-cyclobutyl-1-phenylpropoxyl (5.) radicals, the fragmentation regioselectivity is essentially governed by the stability of the radical formed by β-scission. Accordingly, 4. undergoes exclusive C-cyclobutyl bond cleavage to give acetophenone, whereas with 5., competition between C-cyclobutyl and C-ethyl bond cleavage, leading to propiophenone and cyclobutylphenyl ketone in a 2:1 ratio, is observed.
- Bietti, Massimo,Gente, Giacomo,Salamone, Michela
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p. 6820 - 6826
(2007/10/03)
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- Investigations into the regioselective C-deuteration of acyclic and exocyclic enolates
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Results are reported on the regioselective C-deuteration of a series of related acyclic and exocyclic enolates derived from substituted aryl ketones. We comment on factors, such as the presence of additives and the structural nature of the enolate, that influence the observed C-deuteration and discuss the role of the deuterium donor. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Eames, Jason,Coumbarides, Gregory S.,Suggate, Michael J.,Weerasooriya, Neluka
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p. 634 - 641
(2007/10/03)
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- Direct formation of secondary and tertiary alkylzinc bromides and subsequent Cu(I)-mediated couplings
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Secondary and tertiary alkylzinc bromides can be generated from the direct oxidative addition of Rieke zinc to secondary and tertiary alkyl bromides in high yield. These organozinc reagents have been found to undergo copper-catalyzed conjugate addition, cross-coupling with acid chlorides, and carbocupration to activated alkynes.
- Rieke, Reuben D.,Hanson, Mark V.,Brown, Jeffrey D.,Niu, Q. Jason
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p. 2726 - 2730
(2007/10/03)
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- 1-Aryl-1-hydroxy-1-substituted-3-(4-substituted-1-piperazinyl)-2-propanones and their use in treatment of neurogenic bladder disorders
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Compounds are disclosed having the formula (I): in which R1is a C1 to C12 alkyl, said alkyl being straight or branched chain, saturated or unsaturated, monosubstituted or unsubstituted, said substituents being selected from piperidine, pyrrolidine, morpholine, thiomorpholine or cycloalkyl of 3 to 7 carbons, a cycloalkyl of 3 to 9 carbons, a lower alkylcycloalkyl of 4 to 9 carbons, or a polycycloalkyl of 2 to 3 rings containing 7 to 12 carbons; R2is hydrogen, phenyl, phenyl singly or multiply substituted with halogen, hydroxy, lower alkoxy, methylene dioxy, nitro, lower alkyl or trifluoromethyl, lower alkyl, said alkyl being branched chain or straight, saturated, unsaturated, or cyclic and substituted or unsubstituted, said substituents being selected from thienyl, pyrrolyl, pyridyl, furanyl, hydroxy, lower alkoxy, or acetoxyalkyl wherein the alkyl group has 1 to 3 carbons, phenyl, phenyl substituted with halogen, hydroxy, lower alkoxy, lower alkyl, nitro, methylene dioxy or trifluoromethyl, Phis phenyl or phenyl para-substituted by halogen, lower alkyl, lower alkoxy or trifluoromethyl; and the pharmaceutically acceptable nontoxic salts thereof. The preparation of the compounds, pharmaceutical compositions containing them and their use in the treatment of neurogenic bladder disorder are also enclosed.
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- 1-aryl-1-hydroxy-1-substituted-3-(4-substituted-1-piperazinyl)-2-propanones and their use in treatment of neurogenic bladder disorders
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Compounds are disclosed having the formula: STR1 in which R1 is a C1 l to C12 alkyl, said alkyl being straight or branched chain, saturated or unsaturated, monosubstituted or unsubstituted, said substituents being selected from piperidine, pyrrolidine, morpholine, thiomorpholine or cycloalkyl of 3 to 7 carbons, a cycloalkyl of 3 to 9 carbons, a lower alkylcycloalkyl of 4 to 9 carbons, or a polycycloalkyl of 2 to 3 rings containing 7 to 12 carbons; R2 is hydrogen, phenyl, phenyl singly or multiply substituted with halogen, hydroxy, lower alkoxy, methylene dioxy, nitro, lower alkyl or trifluoromethyl, lower alkyl, said alkyl being branched chain or straight, saturated, unsaturated, or cyclic and substituted or unsubstituted, said substituents being selected from thienyl, pyrrolyl, pyridyl, furanyl, hydroxy, lower alkoxy, or acetoxyalkyl wherein the alkyl group has 1 to 3 carbons, phenyl, phenyl substituted with halogen, hydroxy, lower alkoxy, lower alkyl, nitro, methylene dioxy or trifluoromethyl, Ph is phenyl or phenyl para-substituted by halogen, lower alkyl, lower alkoxy or trifluoromethyl; and the pharmaceutically acceptable nontoxic salts thereof. Pharmaceutical compositions containing the compounds and methods for the treatment of neurogenic bladder disorders are also disclosed. In the preferred compound Ph is phenyl, R1 is cyclobutyl and R2 is benzyl.
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- Bicyclopentanone. Synthesis, Thermal Chemistry, and Photochemistry
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Bicyclopentanone (1) has been prepared in two steps, the key reaction being the ozonolysis of 2-phenylbicyclopentan-2-ol (6).On heating, 1 undergoes cycloreversion to allylketene (13).The activation parameters and solvent effects for this process suggest that the reaction is concerted and that the transition state is relatively nonpolar.The predominant photochemical pathway for 1 is decarbonylation to bicyclobutane (16).Cycloreversion to 13 is a minor reaction mode.Both the thermal and photochemical results are rationalized by considering the high strain energy and novel geometrical features of 1, and, in the latter case, the unusually high energy of its 1(n?excit.) state.
- Sponsler, Michael B.,Dougherty, Dennis A.
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p. 4978 - 4984
(2007/10/02)
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