Kinetic resolution and asymmetric oxidation as combined routes to chiral sulfoxides

Lattanzi, Alessandra; Bonadies, F.; Senatore, Angela; Soriente, Annunziata; Scettri, Arrigo

doi:10.1016/s0957-4166(97)00268-1

“…The crystalline solid was then filtered and washed with cooled (À15 8C) hexane to (R)-4 b (7.60 g, 82 %), ee > 99.5 % (determined by HPLC on a Daicel Chiralpak AS column, with 15 % isopropanol in heptane, and a flow rate of 1.0 mL min À1 ), [a] 20 D = 151 (c = 1.0, acetone); [(Lit. [39] (R)-4 b; ee 95 %); [a] 20 D = 142 (c = 1.5, acetone)].…”

Section: Methodsmentioning

confidence: 99%

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Drago

¹

,

Caggiano

²

,

Jackson

³

2005

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Chiral sulfoxides are an important class of compounds that find increasing use as chiral auxiliaries in asymmetric synthesis. [1,2] Current interest also reflects the existence of products with biological properties containing a sulfinyl group with a defined configuration. [3] Several methods for the asymmetric oxidation of prochiral sulfides have been reported, including the use of chiral oxidants, such as chiral oxaziridines, [4] chiral hydroperoxides, [5] and enzymes. [6,7] The majority of investigations have concentrated on the use of chiral metal complexes [1,3,[8][9][10][11] following the initial reports by Kagan and co-workers [12,13] and Modena and co-workers [14] on the use of variously modified Sharpless reagents for this reaction.One of the most widely studied metal-based systems has been that discovered by Bolm and Bienewald, [15,16] who employed a combination of Schiff bases 1 derived from chiral amino alcohols and [VO(acac) 2 ] (1.0 mol %; acac = acetylacetanoate), with aqueous hydrogen peroxide as the oxidant, in a two-phase system using dichloromethane as the solvent at 20 8C (Scheme 1). The advantages of the system developed by Bolm et al. include high activity, the very simple reaction conditions, and the use of hydrogen peroxide as the oxidant. The only drawback associated with the initial ligands tested was that the levels of enantiomeric excess were good, rather than excellent. Other research groups sought to optimize the system, by variation of the aromatic aldehyde, [17][18][19] the amino alcohol, [20] and the manner of addition of hydrogen peroxide, [21] and in many cases it is striking that the best outcome was usually obtained when the reaction was conducted in dichloromethane at 0 8C. A very nice application of the system developed by Bolm et al. was the asymmetric oxidation of ditert-butyl disulfide, reported by Ellman and co-workers, [22] who have since reported the results of spectroscopic studies with a view to understanding the nature of the active catalytic species better.[23] The nature of the active species is still not completely established, but while spectroscopic studies indicate the presence of a vanadium(v)oxomonoperoxo species, [24] recent calculations suggest that the active species may be a vanadium(v)oxohydroperoxide. [25] Recently, the use of analogous salan ligands has been reported to give high levels of enantioselectivity (95 % ee) in the oxidation of methyl phenyl sulfide, but lower levels of enantioselectivity were observed with other substrates. [26] Anson and co-workers screened a variety of chiral Schiff base ligands, and found that the 3,5-diiodo ligand (S)-2, in combination with [VO(acac) 2 ] gave excellent results in the catalytic asymmetric sulfoxidation of alkyl aryl sulfides with hydrogen peroxide, again in dichloromethane at 0 8C.[27] For example, methyl phenyl sulfide was oxidized to (S)-methyl phenyl sulfoxide (81 %, 90 % ee). Recently, Bolm and coworkers reported that a combination of this ligand with iron is also very effective for the asymmetric ox...

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“…The solution was then gently warmed to give a clear solution, which was allowed to cool to room temperature and then kept at −15 °C overnight to give the product sulfoxide as needles. The crystalline solid was then filtered and washed with cooled (−15 °C) hexane to ( R )‐ 4 b (7.60 g, 82 %), ee >99.5 % (determined by HPLC on a Daicel Chiralpak AS column, with 15 % isopropanol in heptane, and a flow rate of 1.0 mL min −1 ), [ α ]${{{20\hfill \atop {\rm D}\hfill}}}$ =151 ( c =1.0, acetone); [(Lit 39. ( R )‐ 4 b ; ee 95 %); [ α ]${{{20\hfill \atop {\rm D}\hfill}}}$ =142 ( c =1.5, acetone)].…”

Section: Methodsmentioning

confidence: 99%

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Drago

¹

,

Caggiano

²

,

Jackson

³

2005

View full text Add to dashboard Cite

Chiral sulfoxides are an important class of compounds that find increasing use as chiral auxiliaries in asymmetric synthesis. [1,2] Current interest also reflects the existence of products with biological properties containing a sulfinyl group with a defined configuration. [3] Several methods for the asymmetric oxidation of prochiral sulfides have been reported, including the use of chiral oxidants, such as chiral oxaziridines, [4] chiral hydroperoxides, [5] and enzymes. [6,7] The majority of investigations have concentrated on the use of chiral metal complexes [1,3,[8][9][10][11] following the initial reports by Kagan and co-workers [12,13] and Modena and co-workers [14] on the use of variously modified Sharpless reagents for this reaction.One of the most widely studied metal-based systems has been that discovered by Bolm and Bienewald, [15,16] who employed a combination of Schiff bases 1 derived from chiral amino alcohols and [VO(acac) 2 ] (1.0 mol %; acac = acetylacetanoate), with aqueous hydrogen peroxide as the oxidant, in a two-phase system using dichloromethane as the solvent at 20 8C (Scheme 1). The advantages of the system developed by Bolm et al. include high activity, the very simple reaction conditions, and the use of hydrogen peroxide as the oxidant. The only drawback associated with the initial ligands tested was that the levels of enantiomeric excess were good, rather than excellent. Other research groups sought to optimize the system, by variation of the aromatic aldehyde, [17][18][19] the amino alcohol, [20] and the manner of addition of hydrogen peroxide, [21] and in many cases it is striking that the best outcome was usually obtained when the reaction was conducted in dichloromethane at 0 8C. A very nice application of the system developed by Bolm et al. was the asymmetric oxidation of ditert-butyl disulfide, reported by Ellman and co-workers, [22] who have since reported the results of spectroscopic studies with a view to understanding the nature of the active catalytic species better.[23] The nature of the active species is still not completely established, but while spectroscopic studies indicate the presence of a vanadium(v)oxomonoperoxo species, [24] recent calculations suggest that the active species may be a vanadium(v)oxohydroperoxide. [25] Recently, the use of analogous salan ligands has been reported to give high levels of enantioselectivity (95 % ee) in the oxidation of methyl phenyl sulfide, but lower levels of enantioselectivity were observed with other substrates. [26] Anson and co-workers screened a variety of chiral Schiff base ligands, and found that the 3,5-diiodo ligand (S)-2, in combination with [VO(acac) 2 ] gave excellent results in the catalytic asymmetric sulfoxidation of alkyl aryl sulfides with hydrogen peroxide, again in dichloromethane at 0 8C.[27] For example, methyl phenyl sulfide was oxidized to (S)-methyl phenyl sulfoxide (81 %, 90 % ee). Recently, Bolm and coworkers reported that a combination of this ligand with iron is also very effective for the asymmetric ox...

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“…In this latter process the two enantiomers of the sulfoxide are oxidized to sulfone by the chiral reagent at different rates, with decrease of the chemical yield, but increase of the ee values 333 . Interestingly, the presence of ortho-nitro groups on the binaphthol ligand lead to the reversal of enantioselectivity with formation of the (S)-configurated sulfoxide 334 .…”

Section: Sulfidesmentioning

confidence: 99%

Transition Metal Peroxides. Synthesis and Role in Oxidation ReactionsDedicated, on the occasion of his 80th birthday, to our ‘vitae ac studiorum magister in secunda et in adversa fortuna*’ Emeritus Professor Giorgio Modena, Padova University, who showed us the way toward Chemistry.

Conte¹,

Bortolini²

2009

Patai's Chemistry of Functional Groups

1

0

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Kinetic resolution and asymmetric oxidation as combined routes to chiral sulfoxides

Cited by 40 publications

References 18 publications

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Transition Metal Peroxides. Synthesis and Role in Oxidation ReactionsDedicated, on the occasion of his 80th birthday, to our ‘vitae ac studiorum magister in secunda et in adversa fortuna*’ Emeritus Professor Giorgio Modena, Padova University, who showed us the way toward Chemistry.

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Kinetic resolution and asymmetric oxidation as combined routes to chiral sulfoxides

Cited by 40 publications

References 18 publications

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Vanadium‐Catalyzed Sulfur Oxidation/Kinetic Resolution in the Synthesis of Enantiomerically Pure Alkyl Aryl Sulfoxides

Transition Metal Peroxides. Synthesis and Role in Oxidation Reactions*Dedicated, on the occasion of his 80th birthday, to our ‘vitae ac studiorum magister in secunda et in adversa fortuna’ Emeritus Professor Giorgio Modena, Padova University, who showed us the way toward Chemistry.

Contact Info

Product

Resources

About

Transition Metal Peroxides. Synthesis and Role in Oxidation ReactionsDedicated, on the occasion of his 80th birthday, to our ‘vitae ac studiorum magister in secunda et in adversa fortuna*’ Emeritus Professor Giorgio Modena, Padova University, who showed us the way toward Chemistry.