67528-26-1Relevant articles and documents
Enantioselective arene epoxidation under mild conditions by Jacobsen catalyst: The role of protic solvent and co-catalyst in the activation of hydrogen peroxide
Rocha, Mariana,Rebelo, Susana L.H.,Freire, Cristina
, p. 116 - 123 (2013)
The epoxidation of arenes was achieved in high yield and with high enantioselectivity using the system Jacobsen catalyst:hydrogen peroxide:co-catalyst, ethanol as reaction solvent at 40 C. The effect on the catalytic performance of the use of protic (etha
Diazadioxadecalin and salen podands and macrocycles within dynamic combinatorial virtual libraries: Structure, prototropy, complexation and enantioselective catalysis
Star, Alexander,Goldberg, Israel,Fuchs, Benzion
, p. 67 - 77 (2001)
The reactions of L-1,4-diaminobutanediol (3) and D-2,3-diaminobutanediol (4) with salicyl aldehyde provide the tautomeric manifolds of L-1,4-bis(salicylideneamino)-2,3-butanediol (5) and D-2,3-bis(salicylideneamino)-1,4-butanediol (6), respectively. O-alkylation of the salicyl moiety stabilizes the closed dioxadiazadecalin (DODAD) and diazadioxadecalin (DADOD) isomers (7″, 8″) and accordingly, the dialdehyde 1,2-bis(o-formylphenoxy)-ethane (9) led to the respective macrocyclic manifolds (10-10″ and 11-11″). These tautomeric manifolds are typical target-driven dynamic combinatorial virtual libraries, which can be biased by complex formation with metal ions of different ionic radius. A rare instance of simultaneous occurrence of keto-enamine and phenol-imine tautomers in the solid state of 6 was unravelled (X-ray at two temperatures) and the strength of the intramolecular hydrogen bonding (and hence, the extent of ring closure) in 6 is temperature dependent. Compounds 6, 11 and 12-14 constitute a new class of salens, which form heavy and transition metal complexes. Some such Mn(III) complexes are good chirality inducing catalysts, as found in asymmetric indene epoxidation reactions.
Mechanistic Study of the Jacobsen Asymmetric Epoxidation of Indene
Hughes, David L.,Smith, George B.,Liu, Ji,Dezeny, George C.,Senanayake, Chris H.,Larsen, Robert D.,Verhoeven, Thomas R.,Reider, Paul J.
, p. 2222 - 2229 (1997)
The asymmetric epoxidation of indene using aqueous NaOCl, catalyzed by Jacobsen's chiral manganese salen complex, provides indene oxide in 90% yield and 85-88% enantioselectivity. The axial ligand, 4-(3-phenylpropyl)pyridine N-oxide (P3NO), increases the rate of epoxidation without affecting enantioselectivity and also stabilizes the catalyst. These two effects afford a reduction in catalyst loading to 3NO, this rate-limiting oxidation occurs in the organic phase with HOCl as oxidant, as shown by the dependence of the rate on the NaOH concentration. P3NO assists the transport of HOCl to the organic layer as demonstrated by titration studies and by measuring the rates of oxidation of a redox indicator, diphenylbenzidine. On the other hand, stirring speed studies indicate that, in the absence of the ligand, oxidation occurs at the interface. Thus, the axial ligand plays at least two roles in the epoxidation of indene: it stabilizes the catalyst, presumably by ligation, and it increases the epoxidation reaction rate by drawing the active oxidant, HOCl, into the organic layer.
Asymmetric epoxidation of olefins by manganese (III) complexes stabilised on nanocrystalline magnesium oxide
Choudary,Pal, Ujjwal,Lakshmi Kantam,Ranganath,Sreedhar
, p. 1038 - 1042 (2006)
The asymmetric epoxidation of unfunctionalised olefins to epoxides is realised by using manganese(III) complexes stabilised on nanocrystalline magnesium oxide in the presence (1R,2R)-(-)-diaminocyclohexane as a chiral ligand in good yields and up to 91% enantiomeric excess.
Chiral porous poly(ionic liquid)s: Facile one-pot, one-step synthesis and efficient heterogeneous catalysts for asymmetric epoxidation of olefins
Tian, Yabing,Wang, Jixia,Zhang, Shiguo,Zhang, Yan
, (2022/01/26)
Ionic liquids are potential media/solvents for asymmetric synthesis when combined with chiral catalysts, while most reported catalysts are homogenous, making them difficult to separate from the reaction systems. Herein, chiral porous poly(ionic liquid)s (
Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
, p. 5077 - 5085 (2021/08/16)
Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
Asymmetric epoxidation of unfunctionalized olefins with C2-symmetrical diphenol-derived axially coordinated homogeneous chiral bi-Mn(III) salen complexes
Dong, Tianyi,Wu, Xiaoju,Cai, Jiali,Huang, Jing
, p. 57 - 61 (2019/01/19)
A novel type of C2-symmetrical diphenol-derived and axially coordinated homogeneous chiral bi-Mn(III) salen complexes are synthesized and their catalytic effects in asymmetric epoxidation of unfunctionalized olefins are investigated in details. The results show that excellent enantioselectivities and high activities are achieved (enantioselectivities up to >99% in 99.9%) in the absence of expensive NMO. Compared with Jacobsen's catalyst, the configuration of C2-symmetrical homogeneous chiral bi-Mn(III) salen complex contribute to the catalytic reactivity and stability. Furthermore, these new homogeneous catalysts could be easily recovered and reused for 5 cycles without significant loss of their properties.
