- Enantioselective Remote C(sp3)-H Cyanation via Dual Photoredox and Copper Catalysis
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The remote C(sp3)-H cyanation of carboxamides has been described by merging photoredox and copper catalysis in a site-selective and enantiocontrolled manner. The protocol is the integration of photoinduced and nitrogen-centered radical-mediated intermolecular hydrogen atom transfer with chiral copper-complex-catalyzed radical cyanation. This strategy gives enantio-enriched cyanated amides in high yields.
- Chen, Hui,Jin, Weiwei,Yu, Shouyun
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p. 5910 - 5914
(2020/08/12)
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- Deaminative Reductive Cross-Electrophile Couplings of Alkylpyridinium Salts and Aryl Bromides
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A nickel-catalyzed reductive cross-coupling of alkylpyridinium salts and aryl bromides has been developed using Mn as the reductant. Both primary and secondary alkylpyridinium salts can be used, and high functional group and heterocycle tolerance is observed, including for protic groups. Mechanistic studies indicate the formation of an alkyl radical, and controlling its fate was key to the success of this reaction.
- Liao, Jennie,Basch, Corey H.,Hoerrner, Megan E.,Talley, Michael R.,Boscoe, Brian P.,Tucker, Joseph W.,Garnsey, Michelle R.,Watson, Mary P.
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supporting information
p. 2941 - 2946
(2019/04/30)
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- Rhodium-catalyzed intramolecular hydroacylation of 1,2-disubstituted alkenes for the synthesis of 2-substituted indanones
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The intramolecular hydroacylation of 1,2-disubstituted alkenes was considered to be a challenging task due to the side reactions resulted from the lack of additional substituent at 1-position and the low activity caused by the steric hindrance of substituent at 2-position, and an asymmetric version has not been considered possible due to problems associated with the racemization of the products. We have partially solved these problems. Catalyzed by an activated diphosphine-Rh complex and reacted in a selected dihalogenated solvent, the intramolecular hydroacylation of o-(2-arylvinyl)benzaldehydes provided the corresponding 2-aryl-1-indanones in high yields, and its asymmetric variant using o-(2-alkylvinyl)benzaldehydes afforded chiral 2-alkyl-1-indanones in high yields and with moderate enantioselectivities.
- Yuan, Jing,Liu, Chong,Chen, Yan,Zhang, Zhenfeng,Yan, Deyue,Zhang, Wanbin
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p. 269 - 277
(2018/12/05)
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- Chromium-Catalyzed Cross-Coupling Reactions of Alkylmagnesium Reagents with Halo-Quinolines and Activated Aryl Chlorides
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An efficient protocol for chromium(III)-catalyzed C(sp2)-C(sp3) cross-coupling is reported. The alkylations of halo-quinoline and phenacyl derivatives proceed at room temperature within minutes using the tetrahydrofuran-soluble chrom
- Bellan, Andreas B.,Kuzmina, Olesya M.,Vetsova, Violeta A.,Knochel, Paul
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p. 188 - 194
(2016/12/24)
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- Transformation of Trifluorotoluenes Triggered by Titanium(IV) Chloride-Catalyzed Hydrodefluorination using Hydrosilanes
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The titanium tetrachloride-catalyzed hydrodefluorination reaction of trifluorotoluene derivatives was developed using triethylsilane as the reducing agent. The reaction produced various toluene derivatives with high chemoselectivities by means of readily accessible reagents. This hydrodefluorination process was extended to the intramolecular Friedel-Crafts benzylation reaction, furnishing polycyclic aromatics of various ring sizes in good yields.
- Yamada, Takayuki,Saito, Kodai,Akiyama, Takahiko
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- Expeditious construction of a carbobicyclic skeleton via sp3-C-H functionalization: Hydride shift from an aliphatic tertiary position in an internal redox process
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Described herein is the first example of an aliphatic, nonbenzylic hydride shift/cyclization sequence that contains two types of novel sp3-C-H functionalization: (1) construction of a tetraline skeleton via [1,5]-hydride shift/cyclization and (2) [1,6]-hydride shift/cyclization to form a five-membered ring (indane derivatives).
- Mori, Keiji,Sueoka, Shosaku,Akiyama, Takahiko
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p. 2424 - 2426
(2011/04/25)
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- Direct synthesis of water-tolerant alkyl indium reagents and their application in palladium-catalyzed couplings with aryl halides
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A direct result: Alkyl indium reagents are synthesized by the insertion of indium into alkyl halide mediated by CuCl. The synthetic utility of these reagents is demonstrated by their palladium-catalyzed coupling with aryl halides (see scheme). The reagents are compatible with various functional groups, and this makes the protocol generally useful in organic synthesis. DMA=N,N-dimethylacetamide, TBS=tert-butyldimethylsilyl.
- Shen, Zhi-Liang,Goh, Kelvin Kau Kiat,Yang, Yong-Sheng,Lai, Yin-Chang,Wong, Colin Hong An,Cheong, Hao-Lun,Loh, Teck-Peng
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supporting information; experimental part
p. 511 - 514
(2011/03/17)
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- Parallel synthesis of aldehydes and ketone facilitated by a new solid- phase Weinreb amide
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This paper describes a novel supported Weinreb amide resin that facilitates parallel synthesis of aldehydes and ketones on a scale useful for chemical library synthesis. This new resin makes it possible to produce custom aldehydes and ketones from a wide range of carboxylic acids, including N-BOC-amino acids. A variety of commercially unavailable aldehydes are easily synthesized in parallel and obtained in high purity via a simple filtration workup, thus facilitating parallel synthesis of lead optimization libraries that typically require custom synthesis of aldehyde intermediates for development of structure-activity relationships. To demonstrate the utility of this method, we synthesized a small library based on a supported Horner- Emmons reagent. This is the first time it has been shown that aldehydes generated via a supported Weinreb amide could be used directly as reagents in chemical library synthesis employing moisture-sensitive reactions. The analogous solution reaction is not suited for parallel synthesis because of the laborious extractive workup procedure necessary and, at times, the instability of these reactive intermediates.
- Salvino, Joseph M.,Mervic, Miljenko,Mason, Helen J.,Kiesow, Terence,Teager, David,Airey, John,Labaudiniere, Richard
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p. 1823 - 1830
(2007/10/03)
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- Substituted aryl and heteroaryl compounds as E-type prostaglandin antagonists
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This invention relates to substituted and unsubstituted ???(aryl- and heteroaryl-) alkyl-, alkyloxy-, alkylthio-, oxo-, thio-, and alkylamino!- heteroaryl and aryl!- alkylamino-, aminoalkyl-, alkyloxy-, and alkylthio!- aryl and heteroaryl compounds of the formula STR1 and pharmaceutically acceptable salts thereof, which are useful as antagonists of the pain enhancing effects of E-type prostaglandins, to processes for the preparation of such compounds, to pharmaceutical compositions comprising such compounds, and to methods for treating pain comprising the administration of such compounds.
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- Influence of Conformation and Proton-Transfer Dynamics in the Dibenzyl σ-Complex on Regioselectivity in Gattermann-Koch Formylation via Intracomplex Reaction
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The Gattermann-Koch formylations of diphenyl, diphenylmethane, dibenzyl, and 1,3-diphenyl- propane were studied in HF-SbF5, -TaF5, -BF3, -NbF5, and CF3SO3H-SbF5. While usual high para regioselectivity was obtained for diphenyl, diphenylmethane, and 1,3-diphenylpropane, unprecedented ortho regioselectivity was observed for dibenzyl which increased with decreasing the SbF5/dibenzyl molar ratio and with strength of Lewis acids used in HF. A sandwich-like complex for monoprotonated dibenzyl resulting in ortho regioselectivity via the intracomplex reaction was suggested; therefore, the conformations of protonated diphenylmethane, dibenzyl, and 1,3- diphenylpropane and their proton-transfer dynamics were probed by semiempirical calculation (PM3). The calculation predicted that ortho monoprotonation was slightly preferable for dibenzyl, and remarkable preference of dibenzyl over other aromatic compounds was observed in ortho- ortho intramolecular inter-ring proton transfer via a fan-shaped complex rather than a sandwich- like complex. The experimental and theoretical data for dibenzyl are compatible with the intracomplex reaction, whereby CO is protonated by the ortho σ-complex undergoing rapid inter- ring proton transfer to generate formyl cation in the vicinity of the ortho position leading to ortho regioselectivity.
- Tanaka, Mutsuo,Fujiwara, Masahiro,Xu, Qiang,Ando, Hisanori,Raeker, Todd J.
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p. 4408 - 4412
(2007/10/03)
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- Reactivity of functionalized arylcarbenes. 2-Phenylethyl side chains and hetero analogues
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Phenylcarbenes with -X-CH2Ph and -CH2-X-Ph (X = CH2, O, SiMe2) groups in the ortho position were generated thermally and photolytically from diazo or tosylhydrazone precursors. Stereorandom insertion reactions with β-C-H bonds were observed, pointing to a triplet abstraction-recombination mechanism. Large kinetic and stereochemical deuterium isotope effects support this notion. The ample formation of benzocyclobutenes from 2-CH2-X-Ph substrates is due to insertion of the carbenes into ArCH2-X bonds. Addition to the terminal phenyl groups competes with C-H and C-X insertion. The results of benzophenone sensitization and of trapping with methanol suggest that the intramolecular reactions of functionalized arylcarbenes proceed, at best, competitively with spin inversion.
- Kirmse, Wolfgang,Konrad, Wolfgang,Oezkir, Ismail S.
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p. 9935 - 9964
(2007/10/03)
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- Photophysics and photochemistry of intramolecular stilbene-amine exciplexes
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The photophysical and photochemical behavior of a series of trans- (aminoalkyl)stilbenes in which a primary, secondary, or tertiary amine is appended to the stilbene ortho position with a methyl, ethyl, or propyl linker has been investigated. The tertiary
- Lewis, Frederick D.,Bassani, Dario M.,Burch, Eric L.,Cohen, Bliss E.,Engleman, Jeffrey A.,Reddy, G. Dasharatha,Schneider, Siegfried,Jaeger, Wighard,Gedeck, Peter,Gahr, Michael
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p. 660 - 669
(2007/10/02)
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- Intramolecular Generation of Oxonium Ylides from Functionalized Arylcarbenes
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Arylcarbenes carrying alkoxyalkyl groups in the ortho position have been generated by flash pyrolysis and photolysis of appropriate tosylhydrazone sodium salts.In the gas phase and in a aprotic solvents, interaction of the carbenes with the lone electron pairs of oxygen competes efficiently with insertion into C-H bonds.Both five- and six-membered cyclic oxonium ylides have been generated.The ylides 23, 37, 61b, and 74 undergo 1,2 shifts of benzyl groups with ease, even if ring contraction to highly strained benzocyclobutenes is involved (23, 74).The oxonium ylides37 and 61b strongly prefer the nonconcerted Stevens rearrangement to the sigmatropic Sommelet rearrangement, in contrast to analogous ammonium ylides.Alkyl shifts occur to a very minor extent, if at all.Evidence is presented that alcohols intercept both the carbenes and the oxonium ylides.Protonation of the ylides leads to cyclic oxonium ions, which undergo nucleophilic cleavage of the C-O bonds.Acid catalyzed decomposition of the appropriate diazo compounds gives rise to six-membered, but not to five-membered, cyclic oxonium ions, thus confirming the different intramolecular reactivities of arylcarbenes and benzyl cations.The efficiency of carbene interception increases with increasing acidity of the medium, suggesting nucleophilic behavior (protonation) of the arylcarbenes.
- Kirmse, Wolfgang,Kund, Klaus
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p. 1465 - 1473
(2007/10/02)
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