نتایج جستجو برای: 5 tetrasubstituted imidazoles

تعداد نتایج: 1218724  

Journal: :Chemical science 2017
Jevgenijs Tjutrins Bruce A Arndtsen

We describe here a tandem catalytic route to prepare imidazoles in a single operation from aryl iodides, imines and CO. The reaction involves a catalytic carbonylation of aryl halides with imines to form 1,3-dipoles, which undergo spontaneous 1,3-dipolar cycloaddition. Overall, this offers an alternative to coupling reactions to construct the (hetero)aryl-imidazole motif, where variation of the...

2017
Jevgenijs Tjutrins Bruce A. Arndtsen

We describe here a tandem catalytic route to prepare imidazoles in a single operation from aryl iodides, imines and CO. The reaction involves a catalytic carbonylation of aryl halides with imines to form 1,3dipoles, which undergo spontaneous 1,3-dipolar cycloaddition. Overall, this offers an alternative to coupling reactions to construct the (hetero)aryl-imidazole motif, where variation of the ...

Journal: :Acta Crystallographica Section C Crystal Structure Communications 2007

Journal: :Chemical communications 2015
Pankaj Chauhan Suruchi Mahajan Gerhard Raabe Dieter Enders

An unprecedented stereoselective organocatalytic one-pot 1,4-/1,6-/1,2-addition sequence between β-dicarbonyl compounds, β-nitroalkenes and 4-nitro-5-styrylisoxazoles sequentially catalyzed by low loading of a squaramide catalyst and an achiral base has been developed. The protocol opens an efficient entry to isoxazole bearing cyclohexanes with six consecutive stereogenic centers including one ...

Journal: :Organic & biomolecular chemistry 2015
Tarun Kumar Deepti Verma Rubem F S Menna-Barreto Wagner O Valença Eufrânio N da Silva Júnior Irishi N N Namboothiri

A one-pot, two step synthesis of highly substituted imidazoles has been carried out in good to excellent yields for the first time via a cascade intermolecular aza-SN2'-intramolecular aza-Michael addition involving a variety of Morita-Baylis-Hillman acetates of nitroalkenes and amidines in the presence of DABCO at room temperature. The synthetic and biological utility of the products has been d...

Journal: :Beilstein Journal of Organic Chemistry 2009
Andreas A Grauer Burkhard König

C(alpha)-Tetrasubstituted alpha-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic C(alpha)-tetrasubstituted tetrahydrofuran alpha-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of ...

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