Asymmetric Baeyer—Villiger oxidation: control of stereoelectronic demand

Katsuki, Tsutomu

doi:10.1007/s11172-005-0044-7

Cited by 7 publications

(2 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The catalyst has a significant effect at loadings of 2 mol% (Table 3, entries 8 and 9). For the oxidation of bicyclo[3.2.0]heptenone (entry 9), a good regioselectivity with an excess of the “normal” lactone15 was achieved.…”

Section: Methodsmentioning

confidence: 99%

Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide

et al. 2011

View full text Add to dashboard Cite

A series of 3-substituted pyrazinium tetrafluoroborates was prepared as simple analogues of flavinium salts which are efficient organocatalysts for oxidations with hydrogen peroxide. It was shown that pyrazinium derivatives with an electronwithdrawing substituent catalyze mild oxidations of sulfides to sulfoxides and Baeyer-Villiger oxidations in a similar way to flavinium catalysts. The most reactive catalyst, 3-cyanopyrazinium tetrafluoroborate, was efficiently employed in preparative sulfoxidations of aromatic and aliphatic sulfides as well as in Baeyer-Villiger oxidations of cyclobutanones. A proposed mechanism for the catalysis is based on the formation of pyrazine hydroperoxide which is the agent oxidizing the substrate.

show abstract

Section: Methodsmentioning

confidence: 99%

Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide

et al. 2011

View full text Add to dashboard Cite

show abstract

“…One major challenge in the field has been the development of robust catalytic cycles that allow for efficient and rapid catalyst turnover. Moreover, highly enantioselective variants of the BV reaction are almost exclusively performed by enzymatic systems, which by their nature exhibit substrate specificity. Nonenzymatic catalysts for this goal have been demonstrated with organometallic reagents as well as with potential mimics of biological “Baeyer−Villiger-ases”, including systems based on flavin and organophosphoric acid moieties .…”

mentioning

confidence: 99%

A Nonenzymatic Acid/Peracid Catalytic Cycle for the Baeyer−Villiger Oxidation

Peris

Miller

2008

Org. Lett.

View full text Add to dashboard Cite

The combined action of carbodiimide and hydrogen peroxide upon exposure to carboxylic acid catalysts serves to generate transient peracids that can be engaged in the Baeyer-Villiger rearrangement of ketones to lactones. Up to 35 turnovers of the catalytic cycle may be achieved. The conditions are especially useful in the context of reactive cyclohexanones, and allow the use of H 2 O 2 as the terminal oxidant. A singular example of a chiral catalyst demonstrates, in principle, that enantioselective catalysis will be possible with this strategy for catalyst turnover.In spite of the fact that the oxidative conversion of ketones/aldehydes to esters via the Baeyer-Villiger reaction (BV) has been known for more than one hundred years, 1 there remain innumerable optimizations of this venerable reaction yet to be developed. One major challenge in the field has been the development of robust catalytic cycles that allow for efficient and rapid catalyst turnover. Moreover, highly enantioselective variants of the BV reaction are almost exclusively performed by enzymatic systems, 2 which by their nature, exhibit substrate specificity. Nonenzymatic catalysts for this goal have been demonstrated with organometallic reagents 3 as well as with potential mimics of biological "Baeyer- 6 We now wish to establish that the same catalysis concept is portable to the oxidation of ketones (e.g., 2, Scheme 2). This strategy may represent a fundamentally new catalytic cycle for the BV reaction. We targeted carboxyl activation through the combined action of diisopropyl carbodiimide (DIC), and 4-dimethylamino pyridine (DMAP). Capture of intermediate 3 with H 2 O 2 as the terminal oxidant leads to the formation of aspartate peracid (4, Scheme 2). The classical BV reaction then leads to product esters, and regeneration of 2 for re-entry into the catalytic cycle.Initially, exposure of 4-t-butyl-cyclohexanone (eq 1, 7) to 10 mol% of 2 activated by DIC/H 2 O 2 /DMAP resulted in a low yield of lactone 8 (13%; eq 1). We attributed the low yield to reaction of the aspartic peracid with excess DIC to give inactive diacyl peroxide 6 (k 1 ; Scheme 2). 7 This process was already observed in our epoxidation study, and the introduction of a nucleophilic co-catalyst (DMAP or N-methylimidazole; NMI) enabled perhydrolysis of the diacyl peroxide and regeneration of the active peracid (i.e., 6 to 4 in Scheme 2). In the context of the BV, a nucleophilic additive likewise facilitates diacyl peroxide perhydrolysis. 8 Furthermore, the low yield of lactone suggested that the rate of the reaction of peracid with ketone (k 2 , Scheme 2) was slow in comparison to the rate of peracid reaction with DIC (k 1 , Scheme 2). Thus, to compensate, we sought to maintain a low concentration of DIC during the reaction through slow addition of DIC. Indeed, addition of DIC at a rate of 0.13 equiv/hr, in the presence of 0.1 equiv of 2, delivers 8 in 76% yield (eq 1).(1) Having adapted 2 for catalytic BV oxidation, we wondered next if use of more acidic carboxylic acids woul...

show abstract

Baeyer–Villiger Monooxygenases in Organic Synthesis

Kirschner

Bornscheuer

2010

Handbook of Green Chemistry

View full text Add to dashboard Cite

The sections in this article are Introduction General Aspects of the Baeyer–Villiger Oxidation Mechanistic Aspects Chemical Versus Enzymatic Baeyer–Villiger Oxidation Biochemistry of Baeyer–Villiger Monooxygenases Catalytic Mechanism Structural Features Application of Baeyer–Villiger Monooxygenases in Organic Chemistry Isolated Enzymes Versus Whole Cells Baeyer–Villiger Monooxygenases Relevant for Synthetic Applications Representative Synthetic Applications Kinetic Resolutions of Racemic Ketones Desymmetrization of Prochiral Ketones Regiodivergent Transformations Large‐Scale Application Heteroatom Oxidation Protein Engineering Conclusions and Perspectives Acknowledgments

show abstract

Asymmetric Baeyer—Villiger oxidation: control of stereoelectronic demand

Cited by 7 publications

References 23 publications

Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide

Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide

A Nonenzymatic Acid/Peracid Catalytic Cycle for the Baeyer−Villiger Oxidation

Baeyer–Villiger Monooxygenases in Organic Synthesis

Contact Info

Product

Resources

About