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Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation

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ABSTRACT

Bg: Catalytic use of peroxomolybdate for asymmetric transformations has attracted increasing attention due to its catalytic properties and application in catalysis. Herein, we report chiral bisguanidinium dinuclear oxodiperoxomolybdosulfate []2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− ion pair, as a catalyst for enantioselective sulfoxidation using aqueous H2O2 as the terminal oxidant. The ion pair catalyst is isolatable, stable and useful for the oxidation of a range of dialkyl sulfides. The practical utility was illustrated using a gram-scale synthesis of armodafinil, a commercial drug, with the catalyst generated in situ from 0.25 mol% of bisguanidinium and 2.5 mol% of Na2MoO4·2H2O. Structural characterization of this ion pair catalyst has been successfully achieved using single-crystal X-ray crystallography.

No MeSH data available.


Effect of achiral tetrabutylammonium cation.Evaluation of selectivity using 50 mol% of nBu4NHSO4 as achiral ion-pairing reagent with 1 mol% of chiral catalyst (R,R)-1a.
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f8: Effect of achiral tetrabutylammonium cation.Evaluation of selectivity using 50 mol% of nBu4NHSO4 as achiral ion-pairing reagent with 1 mol% of chiral catalyst (R,R)-1a.

Mentions: Reaction selectivity was evaluated using 50 mol% tetrabutylammonium hydrogen sulfate (nBu4NHSO4) as an achiral ion-pairing reagent (Fig. 8). A high level of enantiocontrol can still be achieved, which indicates ion pairing interaction between chiral bisguanidinium and dinuclear oxodiperoxomolybdosulfate anion [(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− accelerates the reaction rate significantly over tetrabutylammonium, promoting the reaction through the desired asymmetric pathway. The stereoinduction observed in the current methodology may be ascribed to ion pairing interaction and other non-covalent interactions between dicationic bisguanidinium, oxodiperoxomolybdosulfate anion, as well as the substrates in the stereoselectivity determining transition state (Supplementary Fig. 5)3354.


Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation
Effect of achiral tetrabutylammonium cation.Evaluation of selectivity using 50 mol% of nBu4NHSO4 as achiral ion-pairing reagent with 1 mol% of chiral catalyst (R,R)-1a.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121337&req=5

f8: Effect of achiral tetrabutylammonium cation.Evaluation of selectivity using 50 mol% of nBu4NHSO4 as achiral ion-pairing reagent with 1 mol% of chiral catalyst (R,R)-1a.
Mentions: Reaction selectivity was evaluated using 50 mol% tetrabutylammonium hydrogen sulfate (nBu4NHSO4) as an achiral ion-pairing reagent (Fig. 8). A high level of enantiocontrol can still be achieved, which indicates ion pairing interaction between chiral bisguanidinium and dinuclear oxodiperoxomolybdosulfate anion [(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− accelerates the reaction rate significantly over tetrabutylammonium, promoting the reaction through the desired asymmetric pathway. The stereoinduction observed in the current methodology may be ascribed to ion pairing interaction and other non-covalent interactions between dicationic bisguanidinium, oxodiperoxomolybdosulfate anion, as well as the substrates in the stereoselectivity determining transition state (Supplementary Fig. 5)3354.

View Article: PubMed Central - PubMed

ABSTRACT

Bg: Catalytic use of peroxomolybdate for asymmetric transformations has attracted increasing attention due to its catalytic properties and application in catalysis. Herein, we report chiral bisguanidinium dinuclear oxodiperoxomolybdosulfate []2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− ion pair, as a catalyst for enantioselective sulfoxidation using aqueous H2O2 as the terminal oxidant. The ion pair catalyst is isolatable, stable and useful for the oxidation of a range of dialkyl sulfides. The practical utility was illustrated using a gram-scale synthesis of armodafinil, a commercial drug, with the catalyst generated in situ from 0.25 mol% of bisguanidinium and 2.5 mol% of Na2MoO4·2H2O. Structural characterization of this ion pair catalyst has been successfully achieved using single-crystal X-ray crystallography.

No MeSH data available.