Modular Synthesis of Chiral N-Protected β-Seleno Amines and Amides via Cleavage of 2-Oxazolidinones and Application in Palladium-Catalyzed Asymmetric Allylic Alkylation
A set of chiral β-seleno amines have been efficiently synthesized via the ring-opening reaction of chiral N-acyl oxazolidin-ones by selenium nucleophiles. These compounds could be transformed into β-seleno amides by reaction with acid chlorides. The present method is applicable to the synthesis of β-chalcogeno amides containing selenium, sulfur and tellurium atoms in good yields. Additionally, these
硒亲核试剂通过手性N-酰基恶唑烷酮的开环反应有效合成了一组手性β-硒胺。这些化合物可以通过与酰氯反应转化为β-硒代酰胺。本方法适用于以良好收率合成含硒、硫和碲原子的β-硫族酰胺。此外,这些新化合物在钯催化的不对称烯丙基烷基化反应中作为配体进行了评估,得到了高达 98% ee 的相应烷基化产物。
Straightforward Synthesis of Non-Natural Selenium Containing Amino Acid Derivatives and Peptides
作者:Antonio L. Braga、Diogo S. Lüdtke、Márcio W. Paixão、Eduardo E. Alberto、Hélio A. Stefani、Luiz Juliano
Synthesis of new fluorous modular chiral ligand derivatives from amino alcohols and application in enantioselective carbon–carbon bond-forming alkylation reactions
作者:Jasquer A. Sehnem、Priscila Milani、Vanessa Nascimento、Leandro H. Andrade、Luciano Dorneles、Antonio L. Braga
DOI:10.1016/j.tetasy.2010.05.015
日期:2010.4
N-Trifluoracyl β-chalcogeno amides and N-perfluoracyl β-thio amide ligands were prepared by a simple and efficient reaction sequence. These new ligands were evaluated in palladium-catalyzed alkylation of rac-(E)-1,3-diphenyl-2-propenyl acetate in the presence of dimethyl malonate and an enantioselectivity of up to 99% was obtained. After catalysis, the fluorous ligand can be easily recovered by liquid–liquid
the respective homochiral α-amino alcohols. The absolute configuration at the created stereogenic centre was assigned by CD spectra and by X-rayanalysis. Conformational analysis of the title compounds was carried out using quantum chemical energy-geometry optimization. Thus established conformational behavior explained the strongly configuration dependent NMR spectral patterns observed for the u and
Chiral lithium amido sulfide ligands for asymmetric addition reactions of alkyllithium reagents to aldehydes
作者:Johan Granander、Richard Sott、Göran Hilmersson
DOI:10.1016/s0957-4166(02)00864-9
日期:2003.2
Six chiral amino sulfides have been synthesised from the amino acids phenylalanine. phenylglycine and valine. These amino sulfides were used as chiral ligands in the asymmetric addition of n-butyllithium and metyllithium to various aldehydes at low temperatures. The highest stereoselectivities were obtained with berizaldehyde. resulting in 1-phenyl-1-pentanol and 1-phenyl-1-ethanol in enantiomeric excesses of > 98.5 and 95% respectively. These stereoselectivities were significantly, higher than those induced by the ether analogues. (C) 2003 Elsevier Science Ltd. All rights reserved.