72607-35-3Relevant articles and documents
Stereoselective protonation of 2-methyl-1-tetralone lithium enolate catalyzed by salan-type diamines
?owicki, Daniel,Watral, Justyna,Jelecki, Maciej,Bohusz, Wiktor,Kwit, Marcin
supporting information, (2021/04/02)
Asymmetric protonation of ketone enolates is a convenient alternative to asymmetric alkylation of enolates that allows to convert racemic ketones into their optically active form. Here, we have reported an efficient enantioselective protonation of 2-methyl-1-tetralone lithium enolate catalyzed by salan-type diamines. A broad series of salan-type catalysts were synthesized, including several previously unknown, and subsequently tested in the title reaction. For the first time, a chiral amine used as organocatalyst has shown better results than as stoichiometric protonating agent. Application of only 10 mol% of salan allows to obtain the title ketone with high yield and enantiomeric excess up to 75%. The DFT calculations of the structure of the catalyst and its complex with lithium enolate were conducted, which makes it possible to propose a likely reaction mechanism.
Vanadium-Catalyzed Oxidative Intramolecular Coupling of Tethered Phenols: Formation of Phenol-Dienone Products
Gilmartin, Philip H.,Kozlowski, Marisa C.
supporting information, p. 2914 - 2919 (2020/04/10)
A mild and efficient method for the vanadium-catalyzed intramolecular coupling of tethered free phenols is described. The corresponding phenol-dienone products are prepared directly in good yields with low catalyst loadings. Electronically diverse tethered phenol precursors are well tolerated, and the catalytic method was effectively applied as the key step in syntheses of three natural products and a synthetically useful morphinan alkaloid precursor.
Mononuclear Salen-Sodium Ion Pairs as Catalysts for Isoselective Polymerization of rac-Lactide
Cui, Yaqin,Jiang, Jinxing,Mao, Xiaoyang,Wu, Jincai
supporting information, p. 218 - 227 (2019/01/04)
A series of mononuclear salen-sodium anions, as the first examples, were synthesized with tetra-alkyl ammonium as a counterpart cation. These complexes are efficient catalysts for the isoselective ring-opening polymerization of rac-lactide; the molecular weights of polymers are under control and molecular weight distributions are narrow when five equivalents of BnOH is used as an initiator. The best isoselectivity value of Pm = 0.82 was achieved at -70 °C. The experimental results together with a density functional theory calculation show that a ligand-assisted activated monomer mechanism is more reasonable than an activated monomer mechanism for this system.
Enantioselective Vanadium-Catalyzed Oxidative Coupling: Development and Mechanistic Insights
Kang, Houng,Herling, Madison R.,Niederer, Kyle A.,Lee, Young Eun,Vasu Govardhana Reddy, Peddiahgari,Dey, Sangeeta,Allen, Scott E.,Sung, Paul,Hewitt, Kirsten,Torruellas, Carilyn,Kim, Gina J.,Kozlowski, Marisa C.
, p. 14362 - 14384 (2018/11/23)
The evolution of a more reactive chiral vanadium catalyst for enantioselective oxidative coupling of phenols is reported, ultimately resulting in a simple monomeric vanadium species combined with a Br?nsted or Lewis acid additive. The resultant vanadium complex is found to effect the asymmetric oxidative ortho-ortho coupling of simple phenols and 2-hydroxycarbazoles with good to excellent levels of enantioselectivity. Experimental and quantum mechanical studies of the mechanism indicate that the additives aggregate the vanadium monomers. In addition, a singlet to triplet crossover is implicated prior to carbon-carbon bond formation. The two lowest energy diastereomeric transition states leading to the enantiomeric products differ substantially with the path to the minor enantiomer involving greater torsional strain between the two phenol moieties.
Preparation, Characterization and Reactivity of a Bis-hypochlorite Adduct of a Chiral Manganese(IV) Salen Complex
Araki, Ikuko,Fukui, Kaoru,Fujii, Hiroshi
supporting information, p. 1685 - 1688 (2018/02/27)
A bis-hypochlorite adduct of a manganese(IV) salen complex having a chiral (R,R)-cyclohexane-1,2-diamine linkage (2-tBu) is successfully prepared and characterized by various spectroscopic methods. The reactions of 2-tBu with various organic substrates show that 2-tBu is capable of sulfoxidation, epoxidation, chlorination, and hydrogen abstraction reactions. However, the enantioselectivity of the epoxidation reactions by 2-tBu is much lower than that reported for the catalytic reactions by Jacobsen's catalyst. The low enantioselectivity is consistent with a planar conformation of the salen ligand, which is suggested by circular dichroism spectroscopy. This study suggests that 2-tBu is not a reactive intermediate of Jacobsen's enantioselective epoxidation catalysis.
Asymmetric Oxidative Coupling of Phenols and Hydroxycarbazoles
Kang, Houng,Lee, Young Eun,Reddy, Peddiahgari Vasu Govardhana,Dey, Sangeeta,Allen, Scott E.,Niederer, Kyle A.,Sung, Paul,Hewitt, Kirsten,Torruellas, Carilyn,Herling, Madison R.,Kozlowski, Marisa C.
, p. 5505 - 5508 (2017/10/25)
The first examples of asymmetric oxidative coupling of simple phenols and 2-hydroxycarbazoles are outlined. Generation of a more vanadium catalyst by ligand design and by addition of an exogenous Br?nsted or Lewis acid was found to be key to coupling the more oxidatively resistant phenols. The resultant vanadium complex is both more Lewis acidic and more strongly oxidizing. Good to excellent levels of enantioselectivity could be obtained, and simple trituration readily provided the products with ≥95% ee.
Development of Highly Active and Regioselective Catalysts for the Copolymerization of Epoxides with Cyclic Anhydrides: An Unanticipated Effect of Electronic Variation
Diciccio, Angela M.,Longo, Julie M.,Rodríguez-Calero, Gabriel G.,Coates, Geoffrey W.
supporting information, p. 7107 - 7113 (2016/07/06)
Recent developments in polyester synthesis have established several systems based on zinc, chromium, cobalt, and aluminum catalysts for the ring-opening alternating copolymerization of epoxides with cyclic anhydrides. However, to date, regioselective proc
Robust bifunctional aluminium-salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides
Rulev, Yuri A.,Gugkaeva, Zalina,Maleev, Victor I.,North, Michael,Belokon, Yuri N.
, p. 1614 - 1623 (2016/04/10)
Two new one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium-salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the catalysts induced the formation of cyclic carbonates under mild reaction conditions (25-35 °C; 1-10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction mixture and reused.
Enantioselective aerobic oxidation of α-hydroxy-ketones catalyzed by oxidovanadium(V) methoxides bearing chiral, N-salicylidene- tert -butylglycinates
Chen, Chien-Tien,Kao, Jun-Qi,Salunke, Santosh B.,Lin, Ya-Hui
supporting information; experimental part, p. 26 - 29 (2011/03/22)
Chiral oxidovanadium(V) methoxides prepared from 3,5-disubstituted-N- salicylidene-l-tert-butylglycines and vanadyl sulfate in air-saturated MeOH serve as highly enantioselective catalysts for asymmetric aerobic oxidations and kinetic resolution of alkyl, aryl, and heteroaryl α-hydroxy-ketones with differed α-substituents at ambient temperature in toluene or TBME (tert-butyl methyl ether). The best scenarios involve the use of complexes which bear the tridendate templates derived from 3,5-diphenyl- or 3-o-biphenyl-5-nitro-salicyaldehyde. The kinetic resolution selectivities of the aerobic oxidation process are in the range of 12 to >1000 based on the selectivity factors (krel).
Synthesis, structures and ethylene polymerization behavior of half-metallocene chromium(iii) catalysts bearing salicylaldiminato ligands
Sun, Mingtai,Mu, Ying,Wu, Qiaolin,Gao, Wei,Ye, Ling
, p. 2979 - 2987 (2011/02/27)
A series of half-metallocene chromium(iii) complexes bearing a salicylaldiminato ligand, Cp′[2-R1-4-R2-6-(CH = NR3)C6H2O]CrCl [Cp′ = Cp (1, 5), Cp* (2, 3, 4, 6, 7, 8); R1 = Ph (1, 2, 3, 5, 6, 8), iPr (4), tBu (7); R2 = H (1, 2, 3), Br (4), NO2 (5, 6, 7, 8); R3 = iPr (1, 2, 5, 6, 7), tBu (3, 4, 8)], were synthesized. The structures of complexes 1, 3-5, 7-8 were determined by single crystal X-ray diffraction analysis. The X-ray crystallographic analysis indicates that these complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlEt3, complexes 1-8 exhibit good to high catalytic activity for ethylene polymerization and produce ultra-high molecular weight polyethylene (PE) under mild conditions. The productivity of these complexes is relatively low when activated with AlMe 3 and AliBu3. Both the productivity of these catalyst systems and the molecular weight of the produced PE can be tuned in a broad range by changing the ligands and the AlR3 co-catalyst. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
