Cationic Cyclizations and Rearrangements Promoted by a Heterogeneous Gold Catalyst
نویسندگان
چکیده
A heterogeneous gold catalyst with remarkable activity for promoting the electrophilic reactions of aryl vinyl ketones and aryl dienyl ketones is described. The catalyst is easy to prepare, is robust, and can be recycled. Low loadings are effective for different types of cationic reactions, including Nazarov cyclizations, lactonizations, and [1,2] shifts.
منابع مشابه
Synthetic Application of Magnetic Nanocomposite Fe3O4@PEG-Au as a Heterogeneous and Reusable Nanocatalyst in The Suzuki Coupling Reactions
In the present study, we carried out chemical synthesis and characterization of Fe3O4@PEG-Au as a magnetic nanocomposite in aqueous solution by chemical co-precipitation of Fe3+ and Fe2+ ions and encapsulated by poly (ethylene glycol) (PEG) in order to enhancing hydrophilicity, biocompatibility and immobilizing gold ions in the presence of NaBH4 as a reducing agent. Nanostructures were characte...
متن کاملEfficient construction of a 3C-xanthone-linked 3C-chromone scaffold by novel double Michael additions and cyclizations.
A novel base-promoted cascade reaction of 2-methyl-3-(1-alkynyl)chromones to produce a 3C-xanthone-linked 3C-chromone scaffold has been developed. This tandem process involves multiple reactions such as Michael additions/cyclizations under mild conditions without a transition metal catalyst and inert atmosphere.
متن کاملCationic Gold Catalyst Poisoning and Reactivation
High gold affinity impurities (halides, bases) in solvents, starting materials, filtration, or drying agents could affect the reactivity of gold catalyst adversely, which may significantly reduce the TON of cationic gold-catalyzed reactions. Use of a suitable acid activator (e.g., HOTf, In(OTf)3) reactivates the gold catalyst and makes the reaction proceed smoothly at low gold catalyst loading.
متن کاملSilica-Supported Cationic Gold(I) Complexes as Heterogeneous Catalysts for Regio- and Enantioselective Lactonization Reactions.
An efficient method for the synthesis of heterogeneous gold catalysts has been developed. These catalysts were easily assembled from readily available silica materials and gold complexes. The heterogeneous catalysts exhibited superior reactivity in various reactions where protodeauration is the rate-limiting step. Dramatic enhancement in regio- and enantioselectivity was observed when compared ...
متن کاملSynthesis of novel functional polycyclic chromones through Michael addition and double cyclizations.
A base-promoted, microwave-assisted one-pot tandem reaction from simple 3-(1-alkynyl)chromones with 2-halobenzylic nitriles (esters or amides) for the synthesis of novel functional polycyclic chromenones has been developed. This tandem process involves multiple reactions, such as Michael addition and double cyclizations without a transition metal catalyst.
متن کامل