78603-97-1Relevant articles and documents
Aluminum Complexes Based on Tridentate Amidoalkoxide NNO-Ligands: Synthesis, Structure, and Properties
Zaitsev, Kirill V.,Cherepakhin, Valeriy S.,Zherebker, Alexander,Kononikhin, Alexey,Nikolaev, Eugene,Churakov, Andrei V.
, p. 11 - 23 (2018)
A series of novel NNO-type ligands 12a-17a, LH2, R1N(CH2CH2NHTs)CHR2CR3R4OH (R1 = Bn, R3 = R4 = H; R2 = H (12a), R2= (S)-Ph (13a), R2= (S)-Bn (14a), R2= (S)-i-Bu (15a); R1 = R2= (R)-Me, R3 = H, R4= (S)-Ph (16a); R1 = Bn, R2= (S)-i-Bu, R3 = R4 = Ph (17a)) was obtained; the ligands LH2 feature various degree of substitution, steric bulkiness, and chirality. Treatment of 11a (R1 = Me, R2 = R3 = R4 = H), 12a-17a, and 18a (R1 = Me, R2 = H, R3 = R4 = Ph) with AlMe3 afforded the complexes 11b-18b, [LAlMe]n (n = 1, 2). It was demonstrated that the structure of the ligand determines the monomeric (16b-18b, R3, R4 = Ph) or dimeric (11b-15b, R3 = R4 = H) structure of the complexes. The discussion of the stereochemical consequences caused by dimerization and chirality of the ligands is performed. The molecular structures of dimeric 11b, 12b, 15b, and monomeric 17b were studied by single-crystal X-ray diffraction. Complexes 11b, 12b, 14b, and 17b are active initiators in ring-opening polymerization of l-lactide in the absence of alcohol. Furthermore, 11b-13b, 17b, and 18b demonstrate an outstanding catalytic activity and selectivity in alcoholysis of l-lactide to give (S,S)-methyl lactyllactate.
Efficient asymmetric addition of diethylzinc to aldehydes using C 2-novel chiral pyridine β-amino alcohols as chiral ligands
Zhang, Weijie,Tang, Ruiren,Yu, Huirong,Gao, Shu
, p. 545 - 551 (2014/07/07)
A series of novel C2-symmetric chiral pyridine β-amino alcohol ligands have been synthesized from 2,6-pyridine dicarboxaldehyde, m-phthalaldehyde and chiral β-amino alcohols through a two-step reaction. All their structures were characterized by 1H NMR, 13C NMR and IR. Their enantioselective induction behaviors were examined under different conditions such as the structure of the ligands, reaction temperature, solvent, reaction time and catalytic amount. The results show that the corresponding chiral secondary alcohols can be obtained with high yields and moderate to good enantiomeric excess. The best result, up to 89% ee, was obtained when the ligand 3c (2S,2R)-2,2-((pyridine-2,6-diylbis(methylene)) bisazanediyl))bis(4-methyl-1,1-diphenylpentan-1-ol) was used in toluene at room temperature. The ligand 3g (2S,2R)-2,2-((1,3-phenylenebis(methylene)) bis(azanediyl))bis(4-methyl-1,1-diphenylpentan-1-ol) was prepared in which the pyridine ring was replaced by the benzene ring compared to 3c in order to illustrate the unique role of the N atom in the pyridine ring in the inductive reaction. The results indicate that the coordination of the N atom of the pyridine ring is essential in the asymmetric induction reaction. Copyright
Design, synthesis, and applications of potential substitutes of t-Bu-phosphinooxazoline in Pd-catalyzed asymmetric transformations and their use for the improvement of the enantioselectivity in the Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates
Belanger, Etienne,Pouliot, Marie-France,Courtemanche, Marc-Andre,Paquin, Jean-Francois
, p. 317 - 331 (2012/02/15)
The design, synthesis, and applications of potential substitutes of t-Bu-PHOX in asymmetric catalysis is reported. The design relies on the incorporation of geminal substituents at C5 in combination with a substituent at C4 other than t-butyl (i-Pr, i-Bu, or s-Bu). Most of these new members of the PHOX ligand family behave similarly in terms of stereoinduction to t-Bu-PHOX in three palladium-catalyzed asymmetric transformations. Electronically modified ligands were also prepared and used to improve the enantioselectivity in the Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates.
