10.1002/anie.201900442
The study presents an enantioselective rhodium-catalyzed allylic alkylation of β,γ-unsaturated α-amino nitriles, offering a novel approach to construct β-stereogenic carbonyl derivatives. This method leverages the catalytic asymmetric alkylation of a homoenolate equivalent, addressing the challenge of manipulating three modes of selectivity: regio- and enantioselectivity, as well as geometrical control. The g-stereogenic cyanoenamine products, resulting from the reaction, can be readily hydrolyzed to yield β-substituted carboxylic acids, providing a convenient pathway to various related carbonyl derivatives. The study underscores the critical role of the E-cyanoenamine products' selective formation, facilitated by the chiral rhodium-allyl intermediate, in achieving high enantiocontrol. The methodology not only provides a practical process but also highlights the utility of molecular dynamics simulation in guiding experimental research for the development of small-molecule inhibitors targeting toxic amyloidogenic protein oligomers.
10.1021/om000629a
This research investigates the mechanisms of diastereomer interconversion in chiral biphepPtX2 complexes, focusing on the role of ligand-ligand exchange and biphenyl atropisomerism. The study aims to understand how these complexes, which are important in asymmetric catalysis, interconvert between different diastereomers. The researchers synthesized and characterized various chiral biphepPtX2 complexes using ligands such as BINOL and TfNO. They found that in the presence of enantiomeric ligands, ligand-ligand exchange dominates the isomerization process, while in the absence of added ligands, higher energy processes involving biphenyl rotation and atrop-inversion are observed.
10.1016/S0022-328X(00)89067-1
The research focuses on the synthesis and molecular structures of chiral ansa-titanocene derivatives with bridged tetrahydroindenyl ligands. The purpose of this study was to develop easily accessible synthetic routes for these stereorigid, chiral organometallic compounds, which have potential applications as chiral hydride- or alkyl-transfer agents. The researchers synthesized racemic ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride and determined its molecular structure, along with that of its meso-isomer and a binaphtholate complex of the (S,S)-enantiomer. They found that the meso-isomer could be converted to the racemic form through exposure to light, a process likely involving a reversible homolytic metal-ring separation. The chiral ansa-titanocene framework was found to be resistant to racemization during ligand exchange. Key chemicals used in the process included 1,2-bis(3-indenyl)ethane, titanium tetrachloride, (S)-(-)-binaphthol, and various solvents and reagents for purification and chromatographic separation.
10.1021/jo9903398
The research aimed to develop diastereo- and enantioselective synthetic methods for α-amino cyclic ethers. These compounds are significant due to their presence in marine natural polycyclic ethers. The study focused on the intramolecular reaction of γ-alkoxyallylstannanes with imines, using various Lewis acids and chiral catalysts. The researchers successfully achieved high diastereoselectivity in the synthesis of trans α-amino cyclic ethers using nonchiral and chiral auxiliary approaches. They also developed the first asymmetric synthesis of α-amino cyclic ethers using a chiral titanium-BINOL complex, achieving high enantioselectivity. Key chemicals used in the process included γ-alkoxyallylstannanes, imines, Lewis acids such as TiCl2(OiPr)2 and ZrCl4, and chiral catalysts like the titanium-BINOL complex.
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