36302-45-1

Upstream product

• 108-94-1 cyclohexanone 
• 107-08-4 1-iodo-propane 
• 227464-42-8 2-bromo-2-(n-propyl)cyclohexanone 
• 94-65-5 2-(n-propyl)cyclohexanone 
• 92207-92-6 C₁₇H₂₇NO₂S 
• 1313885-17-4 C₁₁H₁₇ClO₂ 
• 41302-34-5 2-(methoxycarbonyl)cyclohexanone 
• 57295-92-8 2-(methoxycarbonyl)-2-propylcyclohexanone 
• 6651-36-1 1-(Trimethylsilyloxy)cyclohexene 
• 87296-06-8 1-acetoxy-2-propylcyclohexene 
• 60386-54-1 2-propylidenecyclohexanone 
• 130409-53-9 1-(propionyloxy)-2-propylcyclohexene 
• 72170-97-9 ((S)-2-Methoxymethyl-pyrrolidin-1-yl)-[(R)-2-propyl-cyclohex-(Z)-ylidene]-amine 

Relevant academic research and scientific papers

Mild, racemization free cleavage of ketone SAMP-hydrazones with oxalic acid - Recycling of the chiral auxiliary

Cleavage of ketone SAMP-hydrazones 1a-f with a saturated aqueous oxalic acid solution gives the corresponding ketones 2a-f in excellent yields and with high enantiomeric purity (ee = 90 - 99%). The chiral auxiliary SAMP is recovered from the aqueous phase in good yield (85%) and with unchanged enantiomeric purity. This racemisation free cleavage procedure is compatible with functionalities sensitive to oxidative cleavage conditions, such as ozonolysis, or to strong acids.

Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts

Bifunctional phosphonium/thioureas derived from tert-leucine behaved as highly selective catalysts for enantioselective protonation of enol esters, providing α-chiral ketones in yields of up to 99% with high enantioselectivities (up to 98.5:1.5 er). Control experiments clarified that a bulky tert-butyl group and phosphonium and thiourea moieties were necessary to achieve such high stereoselectivity. In addition, mechanistic investigations indicated the catalyst was converted to the corresponding betaine species, which served as a monomolecular catalyst.

Catalytic asymmetric hydrolysis: Asymmetric hydrolytic protonation of enol esters catalyzed by phase-transfer catalysts

Like an enzyme: Asymmetric hydrolysis of enol esters is accomplished by chiral phase-transfer catalysts under biphasic base hydrolysis conditions. Stoichiometric reactions support the generation of a well-organized chiral ammonium hydroxide species (Q+OH-). Copyright

Induced allostery in the directed evolution of an enantioselective Baeyer-Villiger monooxygenase

The molecular basis of allosteric effects, known to be caused by an effector docking to an enzyme at a site distal from the binding pocket, has been studied recently by applying directed evolution. Here, we utilize laboratory evolution in a different way, namely to induce allostery by introducing appropriate distal mutations that cause domain movements with concomitant reshaping of the binding pocket in the absence of an effector. To test this concept, the thermostable Baeyer-Villiger monooxygenase, phenylacetone monooxygenase (PAMO), was chosen as the enzyme to be employed in asymmetric Baeyer-Villiger reactions of substrates that are not accepted by the wild type. By using the known X-ray structure of PAMO, a decision was made regarding an appropriate site at which saturation mutagenesis is most likely to generate mutants capable of inducing allostery without any effector compound being present. After screening only 400 transformants, a double mutant was discovered that catalyzes the asymmetric oxidative kinetic resolution of a set of structurally different 2-substituted cyclohexanone derivatives as well as the desymmetrization of three different 4-substituted cyclohexanones, all with high enantioselectivity. Molecular dynamics (MD) simulations and covariance maps unveiled the origin of increased substrate scope as being due to allostery. Large domain movements occur that expose and reshape the binding pocket. This type of focused library production, aimed at inducing significant allosteric effects, is a viable alternative to traditional approaches to designed directed evolution that address the binding site directly.

A facile and practical method of preparing optically active α-monosubstituted cycloalkanones by thermodynamically controlled deracemization

Racemic 2-monosubstituted cycloalkanones were converted to R-isomers when TADDOLs (e.g., 1a, b) were used as host molecules in alkaline aqueous MeOH. The efficiency of this thermodynamically controlled deracemization was strongly influenced by the mixture ratio of the solvent, H2O/MeOH. Based on this finding, an improved method of preparing (R)-2-monosubstituted cycloalkanones with higher optical purity was developed. For example, (R)-2-(4-methylbenzyl)cyclohexanone (5) was obtained in 85% yield with 98% ee, when a 1:1 mixture of H2O/MeOH was used as the solvent in the presence of 1a.

Laboratory evolution of robust and enantioselective Baeyer-Villiger monooxygenases for asymmetric catalysis

The Baeyer-Villiger Monooxygenase, Phenylacetone Monooxygenase (PAMO), recently discovered by Fraaije, Janssen, and co-workers, is unusually thermostable, which makes it a promising candidate for catalyzing enantioselective Baeyer-Villiger reactions in organic chemistry. Unfortunately, however, its substrate scope is very limited, reasonable reaction rates being observed essentially only with phenylacetone and similar linear phenyl-substituted analogs. Previous protein engineering attempts to broaden the range of substrate acceptance and to control enantioselectivity have been met with limited success, including rational design and directed evolution based on saturation mutagenesis with formation of focused mutant libraries, which may have to do with complex domain movements. In the present study, a new approach to laboratory evolution is described which has led to mutants showing unusually high activity and enantioselectivity in the oxidative kinetic resolution of a variety of 2-aryl and 2-alkylcyclohexanones which are not accepted by the wild-type (WT) PAMO and of a structurally very different bicyclic ketone. The new strategy exploits bioinformatics data derived from sequence alignment of eight different Baeyer-Villiger Monooxygenases, which in conjunction with the known X-ray structure of PAMO and induced fit docking suggests potential randomization sites, different from all previous approaches to focused library generation. Sites harboring highly conserved proline in a loop of the WT are targeted. The most active and enantioselective mutants retain the high thermostability of the parent WT PAMO. The success of the "proline" hypothesis in the present system calls for further testing in future laboratory evolution studies.

Asymmetric reduction of enones with Synechococcus sp. PCC 7942

Synechococcus sp. PCC 7942, a cyanobacterium, reduced both the endocyclic C-C double bond of s-trans enones and the exocyclic C-C double bond of s-cis enones with high enantioselectivity to afford the corresponding (S)-ketones under illumination.

Asymmetric transformation of enones with Synechococcus sp. PCC 7942

Asymmetric transformation of enones was investigated with cultured cells of Synechococcus sp. PCC 7942 (a cyanobacterium). The cells reduced both the endocyclic C-C double bond of s-trans enones and the exocyclic C-C double bond of s-cis enones with high enantioselectivity to afford optically active α-substituted (S)-ketones under illumination. In addition, the reduction of the double bond of these enones was accompanied by the formation of saturated alcohols. The cells preferentially reduced simple aliphatic ketones rather than cyclic ones to the corresponding (S)-alcohols with excellent enantioselectivity.

Assessing the Substrate Selectivities and Enantioselectivities of Eight Novel Baeyer-Villiger Monooxygenases toward Alkyl-Substituted Cyclohexanones

Genes encoding eight Baeyer-Villiger monooxygenases have recently been cloned from bacteria inhabiting a wastewater treatment plant. We have carried out a systematic investigation in which each newly cloned enzyme, as well as the cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871, was used to oxidize 15 different alkyl-substituted cyclohexanones. The panel of substrates included equal numbers of 2-, 3-, and 4-alkyl-substituted compounds to probe each enzyme's stereoselectivity toward a homologous series of synthetically important compounds. For all 4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in ≥98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer-Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds. More commonly, however, they showed only one type of selectivity. Nonetheless, enzymes with such properties might be useful as parts of a two-step bioprocess where an initial kinetic resolution is followed by a regioselective oxidation on the isolated, optically pure ketone.

A novel reductase participating in the hydrogenation of an exocyclic C-C double bond of enones from Nicotiana tabacum

A novel 74 kDa enone reductase which catalyzes the reduction of the exocyclic C-C double bond of enones was isolated from cultured cells of Nicotiana tabacum. The reductase was found to catalyze the enantiofacially selective reduction of the C-C double bond of 2-alkylidenecyclohexanone to give optically active (S)-2-alkylcyclohexanone.