Chemo-enzymatic Baeyer–Villiger oxidation of 4-methylcyclohexanone via kinetic resolution of racemic carboxylic acids: direct access to enantioenriched lactone

Abstract

A new method for the asymmetric chemo-enzymatic Baeyer-Villiger oxidation of prochiral 4-methylcyclohexanone to (R)-4-methylcaprolactone in the presence of (±)-4-methyloctanoic acid, Candida Antarctica lipase B and 30% aq. H2O2 has been developed. A mechanism for the asymmetric induction based on kinetic resolution of racemic carboxylic acids is proposed.

Optimization of chemoenzymatic Baeyer–Villiger oxidation of cyclohexanone to ε‐caprolactone using response surface methodology

“…In the present work, in order to improve the stability of lipase, T. laibacchii lipase was immobilized on diatomite supports using glutaraldehyde as a crosslinker. In this study, the initial concentration of cyclohexanone was 1.22 M and the concentration of the target product ε‐CL reached about 1.2 M according to the yield of 98.06%, being much higher than that (0.225–0.37 M) with a conversion of 80–90% in the previous other studies . Among them, the highest concentration of 0.37 M was achieved when an ionic liquid was used as solvent, and the yield of caprolactone reached 98.06% because the T. laibacchii lipase used in this study was immobilized by cross‐linking technology, glutaraldehyde was used as a crosslinking agent for T. laibacchii lipase and diatomite support to improve the stability of lipase.…”

“…The conversion of cyclohexanone to ε‐CL based on BV oxidation by the chemoenzymatic method usually involves hydrogen peroxide or urea hydrogen peroxide (UHP) as an oxidant, immobilized Candida antarctica lipase B ( CaL B) as a catalyst, ethyl acetate (EtOAc) as an acyl donor, and a solvent . The concentration range of ε‐CL formed based on the above chemoenzymatic process was about 0.225–0.37 M with conversion of 80–90% in their studies, and this concentration is relatively low and should be greatly increased in order to improve the economy of the process.…”

Organocatalysis and Biocatalysis Hand in Hand: Combining Catalysts in One‐Pot Procedures

“…More complex photochemical approaches can be envisioned that permit redox reactions to take place either on a catalyst or on a substrate/intermediate with a great deal of success. Finally, a general and reliable asymmetric version of the lipase/carboxylic acid/peroxide system is still elusive and a careful design of the carboxylic acid organocatalyst will be required …”

A one-pot and two-stage Baeyer–Villiger reaction using 2,2′-diperoxyphenic acid under biomolecule-compatible conditions

“…Since first reported by Adolf von Baeyer and Victor Villiger in 1899, 3 the Baeyer–Villiger oxidation has stimulated great interest in the chemical community with a wide scope of possible applications spanning multitudinous areas such as the synthesis of natural products, 4 pharmaceutical intermediates 5 and polymer monomers. 6 In general, oxygen, 7 hydrogen peroxide 8 and peracids 9 are the three types of oxidants most commonly used in BV oxidation. A common process of the BV oxidation using O 2 as the oxidant, taking the flavin-dependent monooxygenase for instance, involves the reduction of flavin with nicotinamide adenine dinucleotide phosphate (NADPH) to give an intermediate which then reacts with O 2 to form a flavin-peroxide species which further undergoes a nucleophilic attack on the carbonyl group of the ketone substrate to yield a Criegee intermediate followed by a rearrangement to afford the final product (Scheme 1A).…”