نتایج جستجو برای: disubstituted urea
تعداد نتایج: 40692 فیلتر نتایج به سال:
A novel Pd-catalyzed decarboxylative cross-coupling of oxamic acids with potassium phenyltrifluoroborates has been realized under mild reaction conditions. This method provides an efficient access to N-mono- or N,N-disubstituted benzamides and benzoates.
2,2-Disubstituted cyclic 1,3-diketones containing a tethered electron-deficient alkene undergo chiral phosphoric acid-catalyzed desymmetrizing Michael cyclizations to give bridged bicyclic products in high enantioselectivities. Both bicyclo[3.2.1]octanes and bicyclo[3.3.1]nonanes are accessible using this methodology.
a number of 3-amino-1, 2, 4-triazin-5 (2h)- ones(1) were synthesized and condensed with a-haloketones to give 2,6-disubstituted imidazo [1, 2-b] [1, 2, 4]-triazin-3 (4h)-ones (2). these compounds were reacted further with a - haloketones to yield n-alkylated products (3).
2,7-Disubstituted pyrazolo[1,5-a]pyridines were synthesized in good chemical yields by the reaction of enediynones with hydrazine, followed by addition of copper chloride. This reaction can tolerate many functional groups.
We report the highly selective assembly of unprecedented eta5-1-methylene-1,2-dihydronaphthalenide ligands from the stoichiometric coupling of a phenyl group and two equivalents of disubstituted propargylic alcohols; in this reaction, tetraphenylborate acts as a phenylating agent.
The investigation of the electronic and steric properties of 4,5-disubstituted imidazolylidenes is reported, as well as their successful application as organocatalysts in the formation of gamma-butyrolactones by conjugate Umpolung.
A systematically varied series of conformationally restricted ketones, readily prepared from N-acetyl-D-glucosamine, were tested against representative olefins as asymmetric epoxidation catalysts showing useful selectivities against terminal olefins and, in particular, typically difficult 2,2-disubstituted terminal olefins.
Regio- and stereoselective hydrostannation of allenes by using di-n-butyliodotin hydride (Bu2SnIH) was accomplished to give alpha,beta-disubstituted vinyltins, which induced the synthesis of multi-substituted alkenes in a one-pot procedure.
A synthetic route to enantiopure cis-2,4-disubstituted and 2,4-bridged piperidines is reported, the key step being a stereoselective conjugate addition of an organocuprate to a phenylglycinol-derived unsaturated lactam bearing a substituent at the 8a-position.
A novel carbolithiation of gem-aryl disubstituted methylenecyclopropanes was disclosed by the treatment with BuLi in THF at -78 degree C. The corresponding addition products can be obtained in good to high yields by quenching with various electrophiles.
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