Reduction Of Cycloalkanones Research Articles

A thermodynamic study of ketoreductase-catalyzed reactions 2. Reduction of cycloalkanones in non-aqueous solvents

The equilibrium constants for the ketoreductase-catalyzed reactions (cycloalkanone + 2-propanol = cycloalkanol + acetone) have been measured in n-hexane, n-pentane, and supercritical carbon dioxide SCCO 2 (pressure = (8.0 to 12.0) MPa). The cycloalkanones included in this study were: cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone. The equilibrium constants for the reactions involving cyclobutanone and cyclohexanone were measured in n-hexane over the range T = (288.35 to 308.05) K. The thermodynamic quantities at T = 298.15 K are: K = (0.763 ± 0.001); Δ r G m ∘ = ( 0 . 670 ± 0 . 002 ) kJ · mol - 1 ; Δ r H m ∘ = - ( 1 . 09 ± 0 . 11 ) kJ · mol - 1 , and Δ r S m ∘ = - ( 5 . 9 ± 0 . 4 ) J · K - 1 · mol - 1 for the reaction involving cyclobutanone; and K = (15.7 ± 0.2); Δ r G m ∘ = - ( 6 . 82 ± 0 . 02 ) kJ · mol - 1 ; Δ r H m ∘ = - ( 4 . 6 ± 1 . 0 ) kJ · mol - 1 , and Δ r S m ∘ = ( 7 . 4 ± 3 . 3 ) J · K - 1 · mol - 1 for the reaction involving cyclohexanone, respectively. An inspection of the equilibrium constants for these reactions in n-hexane, n-pentane, and SCCO 2 shows that solvent dependence is not significant. The equilibrium constants of cycloalkanones decrease with increasing value of the number of carbons, N C with the exception of cyclohexanone. The cyclohexanol, which adopts a nearly strainless, idealized tetrahedral conformation around each carbon, is thermodynamically favored and more stable compared to other cycloalkanol rings, and this is reflected in the significantly higher value of the equilibrium constant obtained for this reaction. Comparisons with results obtained by using two independent thermochemical routes are also made.

Gongronella butleri, Schizosaccharomyces octosporus and Diplogelasinospora grovesii: novel microorganisms useful for the stereoselective reduction of ketones

A microbial library composed of 416 strains was selected from public collections. The selection was based on the criteria of the highest biodiversity achievable, being finally composed of 71 bacteria strains, 45 actinomycetes, 59 yeasts, 148 filamentous fungi, 33 marine fungi and 60 basidiomycetes. This set of microorganisms was used for a screening campaign searching for microbial biocatalysts for the stereoselective reduction of carbonylic compounds. All the microorganisms mentioned are mesophilic considering their optimal growth requirements. Gongronella butleri, Diplogelasinospora grovesii and Schizosaccharomyces octosporus were selected as the most interesting strains according to their productivity, their tolerance to high concentrations of ketones and the absence of secondary products in the reduction of cycloalkanones. The reduction of (4 R)- or (4 S)-carvones showed that the stereochemistry of the ketones determine the reduction pathway. Indeed, while (4 S)-carvone yields the (2 R)-alcohol, the (4 R)-carvone carries to dihydrocarveol. D. grovesii and S. octosporus were the strains that displayed better selectivity. The use of resting cells conditions or the lyophilised whole cells reduce the catalytic activity. We describe for the first time a strain, D. grovesii IMI 171018, that is able to produce (2 R,4 S)-carveol from (4 S)-carvone with good yields and enantiomeric excess (ee).

Oxidoreduction between Cycloalkanols and the Corresponding Cycloalkanones in the Cultured Cells of Nicotiana tabacum. Simulation of the Time Courses in the Oxidoreduction

Abstract A method for the simulation of the time courses in the oxidation of cycloalkanols and the reduction of cycloalkanones in the cultured cells of Nicotiana tabacum was developed on the basis of the permeability of these compounds into the cultured cells and the 13C NMR chemical shift of the carbonyl carbon of the cycloalkanones. Further, the method has been applied to the simulation of the time courses in the oxidation of (+)-borneol and (+)-isopinocampheol and the reduction of (−)-carvomenthone in the cultured cells of N. tabacum.

Enzymatic “in vitro” reduction of ketones. III (1) Ring‐size effects in the HLAD‐catalyzed reduction of cycloalkanones.

Enzymatic “in vitro” reduction of ketones. III (1) Ring‐size effects in the HLAD‐catalyzed reduction of cycloalkanones.

Reduction of cycloalkanones by Aspergillus niger

AbstractThe mould Aspergillus niger was grown in a carefully established culture medium containing one of the following test substrates: cyclopentanone, ‐hexanone, ‐heptanone, and their 2‐substituted methyl derivatives. Growth curves, glucose consumption curves and curves showing the course of the oxido‐reduction reaction are given.

Reduction of cycloalkanones by several microorganisms

Investigations were carried out on the reductive capacity of several microorganisms growing in the presence of decalones and monocyclic ketones. Some microorganisms (2 mould strains and 11 bacterial strains) were isolated from the soil, while others (8 mould strains) were obtained from type culture collections. The reductive capacities of these strains towards several cyclic ketones, such as cyclopentanone, -hexanone, and -heptanone and the respective 2-substituted derivatives were studied. In view of further investigations on the mechanism of these reductions, standard procedures (inoculation, incubation, etc.) have been elaborated in order to allow quantitative comparison of the results.

Reduction of cycloalkanones by Aspergillus niger.

The mould Aspergillus niger was grown in a carefully established culture medium containing one of the following test substrates: cyclopentanone, -hexanone, -heptanone, and their 2-substituted methyl derivatives. Growth curves, glucose consumption curves and curves showing the course of the oxido-reduction reaction are given.

Reduction of cycloalkanones by several microorganisms

AbstractInvestigations were carried out on the reductive capacity of several microorganisms growing in the presence of decalones and monocyclic ketones. Some microorganisms (2 mould strains and 11 bacterial strains) were isolated from the soil, while others (8 mould strains) were obtained from type culture collections.The reductive capacities of these strains towards several cyclic ketones, such as cyclopentanone, ‐hexanone, and ‐heptanone and the respective 2‐substituted derivatives were studied. In view of further investigations on the mechanism of these reductions, standard procedures (inoculation, incubation, etc.) have been elaborated in order to allow quantitative comparison of the results.