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.
Chiral Bis(oxazolidine)pyridine-copper-catalyzed enantioselective friedel-crafts alkylation of indoles with nitroalkenes
Sato, Toru,Arai, Takayoshi
, p. 349 - 354 (2014/03/21)
Catalytic asymmetric Friedel-Crafts reaction of indoles with nitroalkenes was catalyzed by the stereochemically tunable bis(oxazolidine)pyridine (PyBodine)-Cu(OTf)2 complex. Using the PyBodine(Val)-Cu(OTf) 2 catalyst gave the Friedel-Crafts ?adducts with highly enantioselective manner. For the 1,4-bis[(E)-2-nitrovinyl]benzene, the reaction proceeded in a meso-trick manner to give the chiral double Friedel-Crafts adduct with 97% enantiomeric excess. Georg Thieme Verlag Stuttgart New York.
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
Large-scale synthesis of Singh's catalyst in a one-pot procedure starting from proline
Berkessel, Albrecht,Harnying, Wacharee,Duangdee, Nongnaphat,Neudoerfl, Joerg-M.,Groeger, Harald
experimental part, p. 123 - 128 (2012/05/20)
A practical one-pot procedure for the preparation of Singh's catalyst from either l-/d-proline or Boc-proline is described. The coupling partner, a chiral amino alcohol, can be prepared and used directly without purification from the corresponding amino acid ester. Moreover, a procedure for tert-butoxycarbonyl (Boc) group removal using concentrated HCl in MeOH-DCM was developed and utilized for the multigram-scale synthesis of Singh's catalyst.
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.
Direct asymmetric N-specific reaction of nitrosobenzene with aldehydes catalyzed by a chiral primary amine-based organocatalyst
Qin, Long,Li, Lei,Yi, Lei,Da, Chao-Shan,Zhou, Yi-Feng
experimental part, p. 527 - 533 (2012/01/11)
Nitroso compounds have two reactive nitrogen and oxygen atoms. It is interesting and important to perform a nitrogen or oxygen selective reaction with interesting substrates. These atom specific reactions are crucial to specifically synthesis of specific compounds. An enantioselective N-specific reaction of nitrosobenzene with unmodified aldehydes was successfully achieved catalyzed first by a variety of primary amine-based organocatalysts with higher yield and enantioselectivity. The bulkier substituted groups of the organocatalyst and two hydrogen bonds from the organocatalyst and the oxygen atom of nitrosobenzene make the reaction preferentially N-specific and predominantly afford R products.
2,4-Dinitrophenol as an effective cocatalyst: Greatly improving the activities and enantioselectivities of primary amine organocatalysts for asymmetric aldol reactions
Da, Chao-Shan,Che, Li-Ping,Guo, Qi-Peng,Wu, Feng-Chun,Xiao, Ma.,Jia, Ya-Ning
experimental part, p. 2541 - 2546 (2009/08/07)
Seven primary amine organocatalysts 1a-g were readily prepared from natural primary amino acids via two steps and then were used to catalyze the direct asymmetric aldol reaction, but they showed very poor enantioselectivities and activities. As an effective cocatalyst, 2,4-dinitrophenol (DNP) dramatically elevated the activities and enantioselectivities of these very inefficient primary amine organocatalysts. This remedial course to the very inefficient organocatalysts by selection and employment of the optimal cocatalyst was particularly cost-effective and environment-beneficial compared with de novo development of catalysts. The highest efficient organocatalytic system that was composed of If and DNP showed high enantioselectivities and good to high diastereoselectivities with a broad spectrum of seven ketones. The linear ketones and cyclopentanone got predominant syn products whereas cyclohexanone mainly gave anti products.
Highly efficient primary amine organocatalysts for the direct asymmetric aldol reaction in brine
Ma, Xiao,Da, Chao-Shan,Yi, Lei,Jia, Ya-Ning,Guo, Qi-Peng,Che, Li-Ping,Wu, Feng-Chun,Wang, Jun-Rui,Li, Wei-Ping
experimental part, p. 1419 - 1424 (2009/12/04)
Organocatalytic systems made up of six primary amine organocatalysts, derived from natural primary amino acids, in combination with 2,4-dinitrophenol (DNP) have proven to be efficient in the presence of brine without further addition of organic solvents. The system formed by 1f and DNP was the most efficient one; it can catalyze the direct aldol reaction with a broad range of ketones and aromatic aldehydes, giving the corresponding aldol products in high yields with up to nearly perfect diastereo- and enantioselectivities (up to 99/1 syn/anti, >99% ee).
Enantioselective addition of thiophenylboronic acids to aldehydes using ZnEt2/Schiff-base catalytic system
Liu, Xiaodong,Qiu, Li,Hong, Liang,Yan, Wenjing,Wang, Rui
experimental part, p. 616 - 620 (2009/08/15)
Using Schiff-base amino alcohols as catalysts which were readily derived from natural amino acids in three steps, a series of valuable optically active thiophenyl methanols (4a-4n) were first obtained in good yields and high enantioselectivities (up to 96% ee) through the asymmetric addition of thiophenylboronic acid to aldehydes in the presence of ZnEt2 in toluene. Crown Copyright
Asymmetric reduction of prochiral ketones with N-sulfonylated amino alcohols as catalysts
Zhou, Zhongqiang,Guo, Yajing
, p. 684 - 696 (2008/09/16)
Novel N-sulfonylated amino alcohols were synthesized from L-amino acids and (+)-camphor, and their application to asymmetric reduction of prochiral ketones with NaBH4-BF3·Et2O is described. Copyright Taylor & Francis Group, LLC.
