Synthesis of New Chiral Aliphatic Amino Diselenides and Their Application as Catalysts for the Enantioselective Addition of Diethylzinc to Aldehydes
作者:Antonio L. Braga、Marcio W. Paixão、Diogo S. Lüdtke、Claudio C. Silveira、Oscar E. D. Rodrigues
DOI:10.1021/ol034773e
日期:2003.7.1
[reaction: see text] A set of chiral aliphatic amino diselenides have been synthesized from readily available starting materials in a straightforward synthetic route via the ring-opening reaction of the parent aziridines. These ligands have been tested as catalysts for the enantioselective addition of diethylzinc to aldehydes. The influence of the alkyl group substituents on the stereoselectivity has
Metal-free ringopening reactions of activated and unactivated aziridines with different silyl chalcogenides are described. Judicious tuning of the reaction conditions enables the synthesis of chiral enantioenriched N-Ts and N-Boc 1,2-mercaptoamines in good yields from the corresponding aziridines and bis(trimethylsilyl)sulfide. N-Protected and N-H unactivated aziridines are efficiently converted into
Seleno-Imine: A New Class of Versatile, Modular N,Se Ligands for Asymmetric Palladium-Catalyzed Allylic Alkylation
作者:Antonio L. Braga、Márcio W. Paixão、Graciane Marin
DOI:10.1055/s-2005-871546
日期:——
The palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate in the presence of chiral seleno-imine ligands derived from an inexpensive and easily available chiral pool was investigated. Excellent yield and enantioselectivity (up to 97% ee) was achieved when ligand 4a was used.
Synthesis of selenium-linked neoglycoconjugates and pseudodisaccharides
作者:Ricardo F. Affeldt、Hugo C. Braga、Lucas L. Baldassari、Diogo S. Lüdtke
DOI:10.1016/j.tet.2012.08.075
日期:2012.12
The introduction of organoselenium moieties within the structure of carbohydrates has received attention recently. Herein, we report on the synthesis of selenium-containing neoglycoconjugates and pseudodisaccharides by the reaction of nucleophilic selenium species, generated from sugar diselenides, with chiral N-Boc aziridines and sugar tosylates. The reaction proceeds with moderate to good yields