Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins

Maity, Nabin Ch.; Rao, Ganga V.S.; Prathap, K. Jeya; Abdi, Sayed H. R.; Kureshy, Rukhsana I.; Khan, Noor‐ul H.; Bajaj, Hari C.

doi:10.1016/j.molcata.2012.10.021

Cited by 18 publications

(16 citation statements)

References 36 publications

(41 reference statements)

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“…For the sake of comparison, we used our previously developed catalysts for the epoxidation reaction [17][18][19]24] (Scheme 2). For the sake of comparison, we used our previously developed catalysts for the epoxidation reaction [17][18][19]24] (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

“…[17] After characterization, these complexes (3 e-3 g) were evaluated for the asymmetric epoxidation of cyano-chromene as a model substrate (Table 1) Table 1, entries 5-7) exhibited significantly better performance than catalysts 3 a-3 d ( Table 1, entries 1-4). Although the overall yield of the homopiperazine macrocycle is the highest among all linkers used in these studied, its Mn III complex has a tendency to become damaged during the catalytic process owing to breakage of the bond between the benzylic carbon atom of the salicylidine moiety and the nitrogen atom of homopiperazine.…”

Section: Resultsmentioning

confidence: 99%

“…Smaller olefins, such as indene, reacted faster than bulkier olefins, such as nitrochromene (Table 3, entries 1 and 6). [17] Furthermore, the rate of formation of indene oxide with time ( Figure 1) indicates that the enantioselectivity of the epoxide remains unaltered throughout the course of the reaction. In the case of epoxidation of cis-bmethylstyrene, the cis/trans ratio in the product epoxide was 84:16, with 92 % ee for the cis epoxide (Table 3, entry 8); this suggested a mostly concerted mechanism involving Mn=O species at the oxygen transfer stage.…”

Section: Resultsmentioning

confidence: 99%

“…All chromenes [28,29] and 3-tert-butyl-5-(chloromethyl)-2-hydroxybenzaldehyde [30] were synthesized according to reported procedures. [17][18][19]24] The absolute configurations of chiral 1-phenylethanol were determined by comparing the sign of optical rotation (obtained from PDR-ALP) with the standard. [31] 1 H and 13 C NMR spectra were recorded on Bruker 200 or 500 MHz spectrometers at ambient temperature.…”

Section: Methodsmentioning

confidence: 99%

“…These studies mainly addressed the issues of improving yield and catalyst recyclability to make the process more acceptable for industry. [17][18][19] The linkers used to build the macrocycle were diethyl tartrate (DET), homopiperazine, 1,1'-binaphthol (BINOL), and 1,3-benzenedimethanol, which were placed across the 5,5'-positions of the salen moiety. Di-and polymeric Mn III -salen complexes have been reported as recyclable enantioselective epoxidation catalysts by linking through the 5,5'- [13][14][15] and 3,3'-positions [16] of salen units by using various types of chiral and nonchiral linkers.…”

Section: Introductionmentioning

confidence: 99%

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Diethyl Tartrate Linked Chiral Macrocyclic Manganese(III)–Salen Complex for Enantioselective Epoxidation of Olefins and Oxidative Kinetic Resolution of Racemic Secondary Alcohols

et al. 2014

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A diethyl tartrate linked chiral macrocyclic manganese(III)–salen (salen=N,N′‐ethylenebis(salicylimine)) complex has been used for the enantioselective epoxidation of nonfunctionalized alkenes, namely, indene and chromenes, as well as oxidative kinetic resolution of racemic alcohols. For the epoxidation reaction, a 2.5 mol % catalyst loading in the presence of pyridine N‐oxide as an axial ligand and urea–H2O2 adduct as an oxidant gave respective epoxides in high yield (>97 %) and enantiomeric excess (ee, up to 92 %). The same catalyst at a loading of 1.5 mol % has provided enantioenriched (ee up to 97 %) secondary alcohols through oxidative kinetic resolution of racemic alcohols. The catalyst can be recovered and reused up to four times with no loss in performance.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diethyl Tartrate Linked Chiral Macrocyclic Manganese(III)–Salen Complex for Enantioselective Epoxidation of Olefins and Oxidative Kinetic Resolution of Racemic Secondary Alcohols

et al. 2014

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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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Pd–Tetrahydrosalan‐Type Complexes as Catalysts for Sonogashira Couplings in Water: Efficient Greening of the Procedure

et al. 2014

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New sulfonated tetrahydrosalen-type ligands and their water-soluble palladium(II) complexes have been synthesized. The palladium(II) complexes catalyze the Sonogashira coupling (23 examples) of various aryl halides (including chloroarenes) with terminal alkynes, with good to excellent conversions under mild conditions (80°C, air, no Cu(I) cocatalyst) in aqueous-organic mixtures and turnover frequencies of up to 2790 h(-1) . Under optimized reaction conditions to minimize environmental contamination, diphenylacetylenes can be isolated in 76-98% yield. The aqueous catalyst solution can be recycled four times with decreasing activity; however, yields between 93 and 98% can still be achieved with extended reaction times. Several water-insoluble products can be isolated in excellent yield by simple filtration and purification by washing with water; this method is used, for the first time, for this type of C-C coupling procedure.

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Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins

Cited by 18 publications

References 36 publications

Diethyl Tartrate Linked Chiral Macrocyclic Manganese(III)–Salen Complex for Enantioselective Epoxidation of Olefins and Oxidative Kinetic Resolution of Racemic Secondary Alcohols

Diethyl Tartrate Linked Chiral Macrocyclic Manganese(III)–Salen Complex for Enantioselective Epoxidation of Olefins and Oxidative Kinetic Resolution of Racemic Secondary Alcohols

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

Pd–Tetrahydrosalan‐Type Complexes as Catalysts for Sonogashira Couplings in Water: Efficient Greening of the Procedure

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