156358-28-0Relevant academic research and scientific papers
Origins of enantioselectivity with nitrogen-sulfur chelate ligands in palladium-catalyzed allylic substitution
Adams, Harry,Anderson, James C.,Cubbon, Rachel,James, Daniel S.,Mathias, John P.
, p. 8256 - 8262 (1999)
The reaction of 1,3-diphenyl-2-propenyl acetate (9) with dimethylmalonate to give the substitution product 10 is effectively catalyzed by Pd complexes containing chiral imine-sulfide chelate ligands derived from amino acids. The ligand of choice, (S)-N-2′-chlorobenzylidene-2-amino-3-methyl-1-thiophenylbutane (6e), prepared in only two steps from (S)-valinol, gave an ee of 94%. Because the explanation of selectivity with the majority of other nitrogen-sulfur chelate ligands in this reaction assumes the selectivity to be controlled by an electronic bias, which contradicts our results, we characterized the Pd-allyl intermediate 14 by X-ray diffraction and solution NMR. The possible mechanism of chirality transfer is discussed. The site of nucleophilic attack on the allyl ligand is not trans to the perceived better π-acceptor ligand (sulfur), which would be analogous to chiral nitrogen-phosphorus systems. This reaction occurs trans to the imine donor, and the enantioselectivity is ultimately controlled by the subtle steric environment of the chiral imine-sulfur chelate ligand, which predisposes the allyl unit of the reaction intermediate to a preferred reaction trajectory. In light of results that emphasize the power of electronic desymmetrization for chiral recognition, these results suggest that electronically dissimilar ligands may not give rise to chiral recognition through electronic dissimilarity.
Pd(II)-Catalyzed Enantioselective γ-C(sp3)-H Functionalizations of Free Cyclopropylmethylamines
Yu, Jin-Quan,Zhuang, Zhe
supporting information, p. 12015 - 12019 (2020/08/06)
Prized for their ability to reliably forge stereocenters with precise regiocontrol from simple and abundant starting materials, substrate-directable enantioselective reactions are widely used in modern organic synthesis. As such, enantioselective C(sp3)-H
Sulfur, selenium and tellurium containing amines act as effective carbonic anhydrase activators
Tanini, Damiano,Capperucci, Antonella,Supuran, Claudiu T.,Angeli, Andrea
, p. 516 - 522 (2019/03/29)
A new series of β-aminochalcogenides were designed and synthesized to identify new carbonic anhydrase activator (CAA) agents as novel tools for the management of several neurodegenerative and metabolic disorders which represent a clinical challenge withou
Mild and selective silicon-mediated access to enantioenriched 1,2-mercaptoamines and β-amino arylchalcogenides
Tanini, Damiano,Borgogni, Cosimo,Capperucci, Antonella
supporting information, p. 6388 - 6393 (2019/04/25)
Metal-free ring opening 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 the corresponding β-arylchalcogeno amines upon treatment with suitable arylchalcogenosilanes. The silicon-mediated ring opening reactions proceed with excellent regioselectivity and stereospecificity, allowing to access a wide array of synthetically and biologically valuable enantioenriched chalcogenoamines.
Synthesis of new fluorous modular chiral ligand derivatives from amino alcohols and application in enantioselective carbon-carbon bond-forming alkylation reactions
Sehnem, Jasquer A.,Milani, Priscila,Nascimento, Vanessa,Andrade, Leandro H.,Dorneles, Luciano,Braga, Antonio L.
scheme or table, p. 997 - 1003 (2010/08/22)
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 pres
Straightforward synthesis of non-natural selenium containing amino acid derivatives and peptides
Braga, Antonio L.,Luedtke, Diogo S.,Paixao, Marcio W.,Alberto, Eduardo E.,Stefani, Helio A.,Juliano, Luiz
, p. 4260 - 4264 (2007/10/03)
A series of non-natural selenium-containing amino acid derivatives and peptides have been synthesized, in a flexible and modular strategy. The peptide coupling reaction between N-protected amino acids and chiral ss-seleno amines afforded the desired products in high yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Chiral lithium amido sulfide ligands for asymmetric addition reactions of alkyllithium reagents to aldehydes
Granander, Johan,Sott, Richard,Hilmersson, Goeran
, p. 439 - 447 (2007/10/03)
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 benzaldehyde, 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.
Sulfur-imine mixed donor chelate ligands for asymmetric catalysis: Enantioselective allylic alkylation
Anderson, James C.,James, Daniel S.,Mathias, John P.
, p. 753 - 756 (2007/10/03)
A new series of sulfur-imine mixed donor chiral ligands, prepared in only two steps from commercially available (S)-valinol, have been shown to give up to 94% enantiomeric excess in a palladium-catalysed allylic substitution reaction.
