Highly Functionalized Organomagnesium Reagents Prepared through Halogen–Metal Exchange

Knöchel, Paul; Döhle, Wolfgang; Gommermann, Nina; Kneisel, Florian F.; Kopp, Felix; Korn, Tobias J.; Sapountzis, Ioannis; Vu, Viet Anh

doi:10.1002/anie.200300579

Cited by 764 publications

(332 citation statements)

References 215 publications

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“…The synthesis of 4-carboxy-Pennsylvania Green (6) was accomplished in 10-steps from commercially available 1,2,4-trifluoro-5-nitrobenzene (7). As shown in Scheme 1, 1-amino-2,4-dimethoxy-5-fluorobenzene (9) was prepared via 8 by a previously reported route.…”

Section: Nih Public Accessmentioning

confidence: 99%

The Pennsylvania Green Fluorophore: A Hybrid of Oregon Green and Tokyo Green for the Construction of Hydrophobic and pH-Insensitive Molecular Probes

et al. 2006

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Fluorescent small molecules are powerful tools for exploring cellular biology. As a more hydrophobic, photostable, and less pH sensitive alternative to fluorescein, we synthesized Pennsylvania Green, a bright, monoanionic fluorophore related to Oregon Green and Tokyo Green.Comparison of membrane probes comprising N-alkyl-3 -cholesterylamine linked to 4-carboxyTokyo Green (pKa ~ 6.2) and 4-carboxy-Pennsylvania Green (pKa ~ 4.8)revealed that only Pennsylvania Green was highly fluorescent in acidic early and recycling endosomes within living mammalian cells.Molecular probes derived from fluorescein (1, Figure 1) are widely used as tools for studies of cellular biology. This green fluorophore is particularly suited for cellular analysis by confocal laser scanning microscopy and flow cytometry due to its excitation maximum at 490 nm, closely matching the 488 nm spectral line of the argon-ion laser. In addition, fluorescein has a high molar absorptivity and excellent quantum yield (0.92 at pH 9). Under physiological conditions (pH 7.4), fluorescein is predominantly a highly hydrophilic dianion. However, the monoanionic form of fluorescein exhibits the relatively high pKa of 6.5, rendering this dye much less fluorescent in acidic solutions. 1 Fluorescein is also relatively susceptible to photobleaching, which is thought to involve reactions with molecular oxygen and proximityinduced reactions of the dye. 2 Oregon Green, a more acidic 2', 7'-difluoro derivative of fluorescein (2, Figure 1), was developed as a less pH-sensitive fluorophore. 3 The appended fluorine atoms reduce the pKa of this dye to 4.8, substantially improving fluorescence at low pH. This compound is also significantly more photostable than fluorescein. However, the high cost and high polarity of Oregon Green limits its utility as a building block for hydrophobic molecular probes.As a more hydrophobic alternative to fluorescein, recent pioneering work by Urano, Nagano, and coworkers replaced the carboxylate of fluorescein with a methyl group. 4 This structural modification yielded a highly fluorescent monoanionic fluorophore termed Tokyo Green (3, Figure 1). This analogue of fluorescein provides a new platform for the design of fluorescent probes.We report here the synthesis of a novel fluorophore termed Pennsylvania Green (4). This fluorophore melds the pH-insensitivity and photostability of Oregon Green with the hydrophobicity of Tokyo Green. To demonstrate the utility of the Pennsylvania Green fluorophore, we compared cellular membrane probes derived from 4-carboxy-Tokyo Green brpeters@chem.psu.edu. (5) and 4-carboxy-Pennsylvania green (6). The lower pKa of the Pennysylvania Green-derived probe enables visualization of early / recycling endosomes within living mammalian cells, and this fluorophore provides a usful tool for analysis of these and related acidic intracellular compartments. NIH Public AccessThe synthesis of 4-carboxy-Pennsylvania Green (6) was accomplished in 10-steps from commercially available 1,2,4-trifluoro-5-nitrobenzene (7)...

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Section: Nih Public Accessmentioning

confidence: 99%

The Pennsylvania Green Fluorophore: A Hybrid of Oregon Green and Tokyo Green for the Construction of Hydrophobic and pH-Insensitive Molecular Probes

et al. 2006

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“…However, it was found that yields of this series of copolymer were relatively low. Hence, it is suggested that for the synthesis of this series of copolymers, other Grignard regents such as isopropylmagnesium chloride (i-PrMgCl) or isopropylmagnesium bromide (i-PrMgBr) together with lithium chloride (LiCl) may be used to afford the copolymers in good yields [29,30]. Since the copolymer synthesized by Wei's group comprising of equal molar ratio of M1!…”

Section: Instrumentationmentioning

confidence: 99%

The effect of intramolecular donor–acceptor moieties with donor–π-bridge–acceptor structure on the solar photovoltaic performance

Wang

Huang²,

Yang³

et al. 2015

Express Polym. Lett.

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Abstract.A series of intramolecular donor-acceptor polymers containing different contents of (E)-1-(2-ethylhexyl)-6,9-dioctyl-2-(2-(thiophen-3-yl)vinyl)-1H-phenanthro[9,10-d]imidazole (thiophene-DOPI) moiety and 4,4-diethylhexylcyclopenta[2,1-b:3,4-b!]dithiophene (CPDT) unit was synthesized via Grignard metathesis (GRIM) polymerization. The synthesized random copolymers and homopolymer of thiophene-DOPI contain the donor-"-bridge-acceptor conjugated structure to tune the absorption spectra and energy levels of the resultant polymers. UV-vis spectra of the three polymer films exhibit panchromatic absorptions ranging from 300 to 1100 nm and low band gaps from 1.38 to 1.51 eV. It is found that more thiophene-DOPI moieties result in the decrease of band gap and lower the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) values of polymers. Photovoltaic performance results indicate that if the content of the intramolecular donor-acceptor moiety is high enough, the copolymer structure may be better than homopolymer due to more light-harvesting afforded by both monomer units.

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“…If Grignard reagents are to be used as nucleophiles in coupling reactions with aryl bromides or chlorides it has been shown that lithium halide adducts of the Grignard reagents show an enhanced reactivity. [54][55][56][57][58] The aim of this research therefore was to gain an understanding of the mutual effects of various transition metals, different spectator ligands, lithium halide additives and the substitution pattern of the respective bromobenzene derivative on the efficiency of the cross-coupling reaction. Moreover, we were highly interested to find a synthetic protocol that allows for the use of iron catalysts with yields that should be comparable to the very well working palladium catalysts.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive study of the effects of spectator ligands, transition metals and lithium halide additives on the efficiency of iron, nickel and palladium-catalyzed cross-coupling reactions of cyclohexyl magnesium bromide with fluorinated bromobenzenes

Dahadha¹,

Imhof²

2013

Arkivoc

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Thirteen mono-, bis-and trifluorinated bromobenzene derivatives have been coupled with cyclohexyl magnesium bromide or the corresponding lithiumchloride or lithiumbromide adducts. Iron, nickel and palladium complexes of the general formula [MCl2(dppx)] (x = (CH2)n, n = 1, 2, 3) have been used as the precatalysts. Palladium based catalysts give high yields of the coupling product with the Grignard reagent itself whereas lithium halides are needed as additives to achieve comparable efficiencies if nickel and iron catalysts are used. Yields also depend on the chain length of the bridging units and on the fact whether fluorine substituents are present in ortho position with respect to bromine.

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Highly Functionalized Organomagnesium Reagents Prepared through Halogen–Metal Exchange

Cited by 764 publications

References 215 publications

The Pennsylvania Green Fluorophore: A Hybrid of Oregon Green and Tokyo Green for the Construction of Hydrophobic and pH-Insensitive Molecular Probes

The Pennsylvania Green Fluorophore: A Hybrid of Oregon Green and Tokyo Green for the Construction of Hydrophobic and pH-Insensitive Molecular Probes

The effect of intramolecular donor–acceptor moieties with donor–π-bridge–acceptor structure on the solar photovoltaic performance

A comprehensive study of the effects of spectator ligands, transition metals and lithium halide additives on the efficiency of iron, nickel and palladium-catalyzed cross-coupling reactions of cyclohexyl magnesium bromide with fluorinated bromobenzenes

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