- Permethylated NHC-Capped α- and β-Cyclodextrins (ICyDMe) Regioselective and Enantioselective Gold-Catalysis in Pure Water
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A series of water-soluble encapsulated copper(I), silver(I) or gold(I) complexes based on NHC-capped permethylated cyclodextrins (ICyDMe) were developed and used as catalysts in pure water for hydration, lactonization, hydroarylation and cycloisomerization reactions. ICyDMe ligands gave cavity-based high regioselectivity in hydroarylations, and high enantioselectivities in gold-catalyzed cycloisomerizations reactions giving up to 98 % ee in water. These ICyDMe are therefore useful ligands for selective catalysis in pure water.
- Zhu, Xiaolei,Xu, Guangcan,Chamoreau, Lise-Marie,Zhang, Yongmin,Mouriès-Mansuy, Virginie,Fensterbank, Louis,Bistri-Aslanoff, Olivia,Roland, Sylvain,Sollogoub, Matthieu
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supporting information
p. 15901 - 15909
(2020/10/12)
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- Catalytic coupling of arene C-H bonds and alkynes for the synthesis of coumarins: Substrate scope and application to the development of neuroimaging agents
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C-H bond functionalization offers strategically novel approaches to complex organic compounds. However, many C-H functionalization reactions suffer from poor compatibility with Lewis basic functional groups, especially amines, which are often essential for biological activity. This study describes a systematic examination of the substrate scope of catalytic hydroarylation in the context of complex amino coumarin synthesis. The choice of substrates was guided by the design and development of the next generation of fluorescent false neurotransmitters (FFNs), neuroimaging probes we recently introduced for optical imaging of neurotransmission in the brain. Comparison of two mild protocols using catalytic PtCl4 or Au (PPh3)Cl/AgSbF6 revealed that each method has a broad and mutually complementary substrate scope. The relatively less active platinum system out-performed the gold catalyst with indole substrates lacking substitution at the C-3 position and provided higher regioselectivity in the case of carbazole-based substrates. On the other hand, the more active gold catalyst demonstrated excellent functional group tolerance, and the ability to catalyze the formation of strained, helical products. The development of these two protocols offers enhanced substrate scope and provides versatile synthetic tools required for the structure-activity examination of FFN neuroimaging probes as well as for the synthesis of complex coumarins in general.
- Vadola, Paul A.,Sames, Dalibor
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p. 7804 - 7814,11
(2020/10/15)
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- A mild titanium-catalyzed synthesis of functionalized amino coumarins as fluorescence labels
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In contrast to Bronsted and other Lewis acids ClTi(OiPr)3 is especially suited to catalyze the formation of amino-substituted coumarins from aminophenols and functionalized β-oxo esters in a Pechmann condensation. This straightforward protocol allows the synthesis of fluorescence labels and false fluorescent neurotransmitters.
- Wirtz, Lisa,Kazmaier, Uli
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supporting information; experimental part
p. 7062 - 7065
(2012/01/05)
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- Microwave acceleration of the Pechmann reaction on graphite/montmorillonite K10: Application to the preparation of 4-substituted 7-aminocoumarins
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Efficient synthesis of 7-aminocoumarins was performed via the Pechmann reaction by microwave irradiation of the reactants on solid support (graphite/montmorillonite K10). In this convenient new methodology, the strong thermal effect due to graphite/microwaves interaction is associated with the acidic catalyst role of the clay.
- Frère, Stéphane,Thiéry, Valérie,Besson, Thierry
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p. 2791 - 2794
(2007/10/03)
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- Pyrylium dyes having a fused rigidized nitrogen-containing ring
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A class of pyrylium dyes, having at least one rigidized, nitrogen-containing heterocyclic ring fused thereto is described. The rigidized dyes are useful lasing components in lasing media.
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