Asymmetric Aminolytic Kinetic Resolution of Racemic Epoxides Using Recyclable Chiral Polymeric Co(III)-Salen Complexes: A Protocol for Total Utilization of Racemic Epoxide in the Synthesis of (<i>R</i>)-Naftopidil and (<i>S</i>)-Propranolol

Kumar, Manish; Kureshy, Rukhsana I.; Shah, Arpan K.; Das, Anjan Kumar; Khan, Noor‐ul H.; Abdi, Sayed H. R.; Bajaj, Hari C.

doi:10.1021/jo4012656

Cited by 34 publications

(14 citation statements)

References 39 publications

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“…Preliminary results suggested that all these complexes except complex 5 (ee, 72%) were showing good activity and moderate to good enantioselectivity in asymmetric HKR of 1,2epoxyhexane. A possible explanation for less reactivity of complex 5 was provided by us in an earlier report, 22 as the distortions (random twists) in the structure of the polymeric salen ligand in case of ligand 5' prepared from racemic BINOL where both R-and S-BINOL motifs may perhaps present randomly in a single polymeric chain.…”

Section: Resultsmentioning

confidence: 92%

Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity

Roy

Barik

Kumar

et al. 2014

Catal. Sci. Technol.

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A series of chiral polymeric Co(III) salen complexes based on a number of achiral and chiral linkers were synthesized and their catalytic performances were assessed in asymmetric hydrolytic kinetic resolution of terminal epoxides. The effect of the linker were judiciously studied and it was found that in case of chiral BINOL based polymeric salen complex 1, there was certain enrichment in catalyst reactivity and enantioselectivity of the unreacted epoxide particularly in the case of shor t as well as long chain aliphatic epoxides. Good isolated yield of the unreacted epoxide (up to 46% out of 50% theoretical yield) along with high enantioselectivity (up to >99%) were obtained in most of the cases using catalyst 1. Further studies exhibited that the catalyst 1 could retain its catalytic activity for six cycles under the present reaction conditions without any significant loss in activity and enantioselectivity. To show the practical applicability of the above synthesized catalyst we have car ried out synthesis of some potent chiral -blockers using complex 1 in moderate yield and high enantioselectivity. The DFT (M06 -L/6-31+G**//ONIOM(B3LYP/6-31G*:STO-3G)) calculations revealed that the chiral BIN OL linker influences the enantioselectivity with Co(III)salen complexes. Further, the transition state calculations show that the R-BINOL linker with (S,S)-(salen)Co(III) complex is energetically preferred over the corresponding S-BINOL linker with (S,S)-(salen)Co(III) complex for HKR of 1,2-epoxyhexane. The role of non-covalent C-H… π interaction and steric effects has been discussed to control the HKR reaction of 1,2 -epoxyhexane.

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Section: Resultsmentioning

confidence: 92%

Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity

Roy

Barik

Kumar

et al. 2014

Catal. Sci. Technol.

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“…Consequently, numerous disalicylaldehydes have been prepared, possessing mostly tert ‐butyl groups in the ortho position of the phenolic group to ensure high enantioselectivities, and therefore interconnected in the para position, away from the active catalytic sites, with a large variety of spacers. The group of Kureshy prepared dialdehydes with linkers possessing additional stereogenic centers from binaphthol or diethyltartrate derivatives, or free of them but having different flexibility properties . Nucleophilic substitution was readily performed between the engaged diols or diamines with chloromethylsalicylaldehyde, and condensation occurred subsequently with enantiopure cyclohexyldiamine to deliver linear chiral polymers (Scheme ) which were characterized by classical methods and GPC analyses, revealing a high molecular weight and a narrow polymer distribution index.…”

Section: Polymerization Of Salen Derivativesmentioning

confidence: 99%

“…The group of Kureshy prepared dialdehydes with linkers possessing additional stereogenic centers from binaphthol or diethyltartrate derivatives, or free of them but having different flexibility properties. [49] Nucleophilic substitution was readily performed between the engaged diols or diamines with chloromethylsalicylaldehyde, and condensation occurred subsequently with enantiopure cyclohexyldiamine to deliver linear chiral polymers (Scheme 14) which were characterized by classical methods and GPC analyses, revealing a high molecular weight and a narrow polymer distribution index. After introduction of cobalt salts, these polymers were tested to catalyze the asymmetric kinetic aminolysis of various epoxides.…”

Section: Polymerization Of Salen Derivativesmentioning

confidence: 99%

Chiral Salen Complexes for Asymmetric Heterogeneous Catalysis: Recent Examples for Recycling and Cooperativity

2019

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Chiral salen complexes are privileged and versatile catalysts used in a wide variety of enantioselective transformations. Researches for their use in multicatalysis, including cooperative as well as tandem processes, are more recent, but many reports already highlight the important effect of the salen ligand structure on reaction rates and/or selectivities. This review article thus outlines the literature covering last five years, on the current developments of chiral polymetallic salen complexes used in asymmetric heterogeneous catalysis; their preparation, their efficiency as catalysts in various reactions and their recyclability are highlighted according to the immobilization procedures involved for their heterogenization. These methods include grafting on organic or inorganic supports insuring easy recovery by simple filtration. Polymerization processes are also part of recent research, leading to high densities of catalytic sites to favor their cooperativity. Combination of salen complexes via non covalent interactions or their introduction on MOFs and COFs networks is currently in full expansion, with examples of highly functionalized and enantioenriched products issued from tandem catalysis.

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“…Some quinazoline-type ligands or their metal complexes are used as biological models for understanding the structure of biomolecules and biological processes [12][13][14], and have high selectivity recognition [15] and catalytic activity [16,17]. Acetate ions often play an important role in coordination chemistry, adopting binding modes such as terminal monodentate or chelating to one metal center [18]. Cobalt(II) complexes have been widely investigated [19][20][21], but cleavage of two C-N bonds of Schiff base-type ligands have not been observed.…”

Section: Introductionmentioning

confidence: 99%

Two 1-D and 2-D cobalt(II) complexes: synthesis, crystal structures, spectroscopic and electrochemical properties

Chai

Huang

Zhang

et al. 2015

Journal of Coordination Chemistry

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Two new cobalt(II) complexes have been synthesized via complexation of Co(II) acetate tetrahydrate with HL 1 and HL 2 originally. HL 1 , HL 2 and their corresponding Co(II) complexes were characterized by IR, 1 H NMR spectra, as well as by elemental analysis and UV-Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C-X···π bonding interactions construct the 1-D infinite chain [Co(L 3 ) 2 ]·CH 3 OH·CH 3 COCH 3 and Co(L 4 ) 2 into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.Two new cobalt(II) complexes, [Co(L 3 ) 2 ]·CH 3 OH·CH 3 COCH 3 (1) (HL 3 = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L 4 ) 2 (2) (HL 4 = 1-(2-{[(E)-3, 5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL 1 and HL 2 . HL 1 , HL 2 , and their corresponding Co(II) complexes were characterized by IR, 1 H NMR spectra, as well as by elemental analysis and UV-Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by *Corresponding author.single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C-X···π bonding interactions construct the 1-D infinite chain [Co(L 3 ) 2 ]·CH 3 OH·CH 3 COCH 3 and Co(L 4 ) 2 into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.

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Asymmetric Aminolytic Kinetic Resolution of Racemic Epoxides Using Recyclable Chiral Polymeric Co(III)-Salen Complexes: A Protocol for Total Utilization of Racemic Epoxide in the Synthesis of (R)-Naftopidil and (S)-Propranolol

Cited by 34 publications

References 39 publications

Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity

Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity

Chiral Salen Complexes for Asymmetric Heterogeneous Catalysis: Recent Examples for Recycling and Cooperativity

Two 1-D and 2-D cobalt(II) complexes: synthesis, crystal structures, spectroscopic and electrochemical properties

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