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Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation

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.


Bisguanidinium ion pairs (R,R)-1a and (R,R)-1b.(a) Structure of bisguanidinium salts. (b) X-ray crystallographic structure of [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− (R,R)-1b (ellipsoids at 50% probability).
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f2: Bisguanidinium ion pairs (R,R)-1a and (R,R)-1b.(a) Structure of bisguanidinium salts. (b) X-ray crystallographic structure of [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− (R,R)-1b (ellipsoids at 50% probability).

Mentions: We have recently developed pentanidium27282930 and dicationic bisguanidinium (BG) as efficient phase-transfer3132 and ion pair catalysts3334353637. We have utilized bisguanidinium permanganate ion pair catalyst for the enantioselective oxidation of alkenes38. The precise stereocontrol exhibited by bisguanidinium encouraged us to explore other anionic metallic species for asymmetric transformations39. Herein, we describe our serendipitous discovery of chiral bisguanidinium dinuclear oxodiperoxomolybdosulfate [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− ion pair catalyst (Fig. 2). This ion pair catalyst is stable and isolatable or it can be generated in situ. In a continuation of our current efforts towards developing practical approaches to enantiopure sulfoxides294041, we report a simple and scalable methodology for enantioselective sulfoxidation using this ion pair catalyst42434445.


Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation
Bisguanidinium ion pairs (R,R)-1a and (R,R)-1b.(a) Structure of bisguanidinium salts. (b) X-ray crystallographic structure of [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− (R,R)-1b (ellipsoids at 50% probability).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Bisguanidinium ion pairs (R,R)-1a and (R,R)-1b.(a) Structure of bisguanidinium salts. (b) X-ray crystallographic structure of [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− (R,R)-1b (ellipsoids at 50% probability).
Mentions: We have recently developed pentanidium27282930 and dicationic bisguanidinium (BG) as efficient phase-transfer3132 and ion pair catalysts3334353637. We have utilized bisguanidinium permanganate ion pair catalyst for the enantioselective oxidation of alkenes38. The precise stereocontrol exhibited by bisguanidinium encouraged us to explore other anionic metallic species for asymmetric transformations39. Herein, we describe our serendipitous discovery of chiral bisguanidinium dinuclear oxodiperoxomolybdosulfate [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− ion pair catalyst (Fig. 2). This ion pair catalyst is stable and isolatable or it can be generated in situ. In a continuation of our current efforts towards developing practical approaches to enantiopure sulfoxides294041, we report a simple and scalable methodology for enantioselective sulfoxidation using this ion pair catalyst42434445.

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.