نتایج جستجو برای: friedel
تعداد نتایج: 1232 فیلتر نتایج به سال:
Regioselective methanesulfonylation of simple aromatics using methanesulfonic anhydride can be achieved over zeolite catalysts. For example, methanesulfonylation of toluene over various cation-exchanged zeolite beta catalysts affords higher para-selectivity in the synthesis of methyl tolyl sulfone than standard Friedel-Crafts methanesulfonylation utilising aluminium chloride.
An esterification/Friedel-Crafts-cyclization approach permitted the first successful synthetic entry into the oxacyclododecindione subclass of the dihydroxyphenylacetic acid lactone-type natural products. This route allowed the preparation of two highly active anti-inflammatory fungal secondary metabolites 14-deoxyoxacyclododecindione and 14-deoxy-4-dechlorooxacyclododecindione as well as their...
The asymmetric Povarov reaction of N-arylimines with 2- and 3-vinylindoles has been developed using a chiral phosphoric acid ((S)-TRIP) as catalyst. The peculiar reactivity of vinylindoles allowed also the disclosure of a Povarov Friedel-Crafts sequence, and the trapping of the reaction intermediate with nucleophilic species, thus providing a versatile platform for the preparation of highly ena...
Friedel-Crafts reactions of isopropyl-substituted benzenes with phthalic anhydride in the presence of aluminium trichloride, followed by cyclization of the products with strong sulfuric acid give, as expected, anthraquinones. The syntheses, however, often afford more than one anthraquinone. In some cases the isopropyl groups migrate cleanly to other ring positions; in other cases they are lost.
Simple and convenient Lewis acid-catalyzed Friedel-Crafts alkylations of 2-oxindoles as electron rich aromatics with 3-hydroxy-2-oxindoles as electron deficient partners have been developed. The reaction afforded a variety of dimeric 2-oxindoles with a C-3/C-5' linkage having an all-carbon quaternary center at the pseudobenzylic position in high yields.
Cyclization of 1,6-diynes promoted by stoichiometric Ga(III) halides produces vinyl halides in good to excellent yields. Under acidic conditions, initially formed iodocyclization products undergo in situ Friedel-Crafts cyclizations, giving access to iodoindenopyridines. Application of the vinyl halides in cross-coupling reactions has been explored, and mechanistic aspects of the cyclization are...
An efficient relay catalytic process involving Au(i)/Brønsted acid to access various polysubstituted cyclopentannulated indoles from easily accessible 1-(2-aminophenyl)prop-2-ynols and readily available 1,3-dicarbonyls has been developed. In an unprecedented event, the intermediate 2-indolylmethyl cations undergo the cation-Ene reaction with various 1,3-dicarbonyls followed by an intramolecular...
A highly enantioselective dearomative cascade reaction between 2-isocyanoethylindoles and 3-alkenyl-oxindoles was realized using a chiral N,N'-dioxide-Mg(II) complex catalyst. This reaction provides a straightforward access to polycyclic 3-spirooxindoles bearing cyclopenta[b]indole units with four contiguous stereocenters in excellent yields and moderate to good stereoselectivities via a Michae...
Remarkably high and regular enantioselectivities are obtained in Friedel-Crafts alkylation reactions involving alpha'-hydroxy enone templates and Cu(II)-bis(oxazoline) complexes as catalysts. The simple elaboration of adducts provides a route to enantioenriched aldehydes, carboxylic acids, and ketones containing the pyrrole and indole frameworks.
Introduction of a polyfluoroalkyl group into aromatic compounds was achieved by Friedel-Crafts reaction using (1-chloro-1-hydroperfluoroalkyl) sulfides 1, and the subsequent desulfurizing-difluorination of the resulting product using IF5 / Et3N-nHF. Perfluoroethyl, 1,1,2,2,3,3-hexafluoropropyl, and 1,1,2,2,3,3,4,4,5,5-decafluoropentyl groups were introduced to various aromatic compounds by this...
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