51703-97-0

Upstream product

• 4536-23-6 2-methylhexanoic acid 
• 542-69-8 1-iodo-butane 
• 69856-85-5 N-((1S,2R)-2-hydroxy-1-methyl-2-phenyl-ethyl)-N-methyl-propionamide 
• 112-92-5 1-octadecanol 
• 92053-21-9 (S)-1-<2-(1-Hydroxy-1-methylethyl)pyrrolidin-1-yl>propan-1-on 
• 111-87-5 octanol 
• 112-30-1 1-Decanol 
• 5978-70-1 (R)-Octan-2-ol 
• 6169-06-8 (S)-2-Octanol 
• 111555-17-0 (R)-2-methylhexanoic acid (S)-1-phenylethylamide 
• 66050-98-4 (2R)-methyl-1-hexanol 
• 134840-22-5 7-methyl undecan-5-ol-6-one 
• 102680-24-0 (R)-(-)-3-methyl-1-phenyl-1-heptene 
• 93553-73-2 (2R,4E)-2-Methyl-4-hexenoic acid 

Downstream Products

• 97424-48-1 (R)-1-bromo-2-methylhexane 
• 105977-64-8 (2R,3R,4R,5S,6R,8S,10S)-10-benzyloxy-8-benzyloxymethyl-2-ethyl-3-methyl-4-<(R)-methylhexanoyl>-1,7-dioxaspiro<5.5>undecan-5-ol 
• 106155-08-2 (R)-2-Methyl-hexanoic acid (2R,3R,4R,5S,6R,8S,10S)-10-benzyloxy-8-benzyloxymethyl-5-(tert-butyl-dimethyl-silanyloxy)-2-ethyl-3-methyl-1,7-dioxa-spiro[5.5]undec-4-yl ester 
• 13151-35-4 (R)-5-Methyldecane 
• 108645-33-6 (+)-(2R)-N-((1'R)-1-phenethyl)-2-methylhexanamide 

Relevant academic research and scientific papers

Lipase-catalyzed enantioselective resolution of (R,S)-N-2-methylalkanoyl-3- (2-pyridyl)pyrazoles in organic solvents

The lipase-catalyzed resolution of (R,S)-pyrazolides containing a 2-aryl substituent to the α-chiral center has been successfully extended to (R,S)-N-2-methylalkanoyl-3-(2-pyridyl)pyrazoles (1-4) containing different alkanoyl-chain lengths. The best reaction condition for CALB-catalyzed hydrolysis of (R,S)-N-2-methylheptanoyl-3-(2-pyridyl)pyrazole (1) in water-saturated MTBE at 35 °C is selected, leading to an excellent enantioselectivity (VR/VS > 100) with improved initial specific activities in comparison with that of (R,S)-N-2-phenylpropionyl-3-(2- pyridyl)pyrazole. The thermodynamic analysis for the hydrolysis of 1 demonstrates great influences of water content and solvent hydrophobicity on varying the ehthalpic and entropic contributions in water-saturated and anhydrous MTBE and IPE, and leads to an excellent enthalpy-entropy compensation relationship ΔΔS = 3.113ΔΔH + 33.86 (r2 = 0.999). Moreover, a thorough kinetic analysis for all substrates indicates that a critical valeroyl-chain length for obtaining the enantiomer discrimination and improved lipase activity for the fast-reacting (R)-pyrazolide is needed. Copyright

Are Highly Stable Covalent Organic Frameworks the Key to Universal Chiral Stationary Phases for Liquid and Gas Chromatographic Separations?

High-performance liquid chromatography (HPLC) and gas chromatography (GC) over chiral stationary phases (CSPs) represent the most popular and highly applicable technology in the field of chiral separation, but there are currently no CSPs that can be used for both liquid and gas chromatography simultaneously. We demonstrate here that two olefin-linked covalent organic frameworks (COFs) featuring chiral crown ether groups can be general CSPs for extensive separation not only in GC but also in normal-phase and reversed-phase HPLC. Both COFs have the same 2D layered porous structure but channels of different sizes and display high stability under different chemical environments including water, organic solvents, acids, and bases. Chiral crown ethers are periodically aligned within the COF channels, allowing for enantioselective recognition of guest molecules through intermolecular interactions. The COF-packed HPLC and GC columns show excellent complementarity and each affords high resolution, selectivity, and durability for the separation of a wide range of racemic compounds, including amino acids, esters, lactones, amides, alcohols, aldehydes, ketones, and drugs. The resolution performances are comparable to and the versatility is superior to those of the most widely used commercial chiral columns, showing promises for practical applications. This work thus advances COFs with high stability as potential universal CSPs for chromatography that are otherwise hard or impossible to produce.

Chemoenzymatic Cascade Synthesis of Optically Pure Alkanoic Acids by Using Engineered Arylmalonate Decarboxylase Variants

Arylmalonate decarboxylase (AMDase) catalyzes the cofactor-free asymmetric decarboxylation of prochiral arylmalonic acids and produces the corresponding monoacids with rigorous R selectivity. Alteration of catalytic cysteine residues and of the hydrophobic environment in the active site by protein engineering has previously resulted in the generation of variants with opposite enantioselectivity and improved catalytic performance. The substrate spectrum of AMDase allows it to catalyze the asymmetric decarboxylation of small methylvinylmalonic acid derivatives, implying the possibility to produce short-chain 2-methylalkanoic acids with high optical purity after reduction of the nonactivated C=C double bond. Use of diimide as the reductant proved to be a simple strategy to avoid racemization of the stereocenter during reduction. The developed chemoenzymatic sequential cascade with use of R- and S-selective AMDase variants produced optically pure short-chain 2-methylalkanoic acids in moderate to full conversion and gave both enantiomers in excellent enantiopurity (up to 83 % isolated yield and 98 % ee).

Application of acyclic chiral auxiliaries on alkylation reactions

The application in alkylation reactions of an acyclic chiral auxiliary is described. The synthesis is straightforward from a chiral primary amine and a double acylation. A characteristic of this auxiliary is its modular design formed by an achiral part (acyl) and a chiral component (primary amine) so it can be tuned for different reactions without difficulty. The alkylation proceeds with excellent diastereoselectivity because the conformational flexibility of the enolate is restricted by the formation of a chelate and the allylic 1,3-strain.

Palladium nanoparticle-graphene catalysts for asymmetric hydrogenation

We report for the first time the application of palladium nanoparticle-graphene (Pd/Gn) catalysts in the asymmetric hydrogenation of aliphatic α,β-unsaturated carboxylic acids using cinchonidine as chiral modifier. Pd/Gns were prepared by deposition-preci

Achiral amine additives in the enantioselective hydrogenation of aliphatic α,β-unsaturated acids over cinchonidine-modified Pd/Al 2O3 catalyst

The effect of the achiral amine additive structure was studied on the enantioselective hydrogenation of (E)-2-methyl-2-butenoic acid and (E)-2-methyl-2-hexenoic acid over Pd/Al2O3 catalyst modified by cinchonidine. It was found that

Fundamental insights into the enantioselectivity of hydrogenations on cinchona-modified platinum and palladium

The influence of the configuration at the C8 and C9 positions of cinchona alkaloids was investigated by comparing the efficiency of cinchonidine, cinchonine, and 9-epi-cinchonidine as chiral modifiers. In the hydrogenation of ketones (methyl benzoylformate, ketopantolactone, methylglyoxal dimethylacetal, 2,2,2-trifluoroacetophenone) on Pt, a change in the configuration at C9 did not affect the absolute configuration of the main products; however, the ees and rates dropped significantly. In the hydrogenation of α-functionalized olefins (E-2-methyl-2-hexenoic acid, 2-phenylcinnamic acid, and 4-methoxy-6-methyl-2H-pyran-2-one) on Pd, replacement of cinchonidine or cinchonine by epi-cinchonidine diminished the rates and almost eliminated the enantioselection, indicating that a subtle combination of C8 and C9 configurations is required on Pd. DFT calculations of the adsorption of the modifiers and the nonlinear behavior of modifier mixtures revealed that the lower reaction rates observed for 9-epi-cinchonidine-modified surfaces cannot be related to different adsorption strength of this modifier. Additionally, substrate-modifier docking interactions are presented.

Pseudoephenamine: A practical chiral auxiliary for asymmetric synthesis

Unrestricted: Pseudoephenamine is introduced as a versatile chiral auxiliary and an alternative to pseudoephedrine in asymmetric synthesis. It is free from regulatory restrictions and leads to remarkable stereocontrol in alkylation reactions, especially in those that form quaternary carbon centers. Amides derived from pseudoephenamine exhibit a high propensity to be crystalline substances, and provide sharp, well-defined signals in NMR spectra. Copyright

Stereochemical investigations reveal the mechanism of the bacterial activation of n-alkanes without oxygen

Anaerobic growth of the bacterium strain HxN1 with n-hexane gives nearly equal amounts of (2R,1 R)- and (2S,1 R)-(1-methylpentyl)succinate, which are formed by the radical addition of the hydrocarbon to fumarate (see scheme). The highly selective attack on the pro-S hydrogen atom at C2 of n-hexane is associated with inversion of the configuration at C2 during binding to fumarate and exhibits isotopic discrimination against a C-2H bond. Copyright

Evaluation of snake venom phospholipase A2: Hydrolysis of non-natural esters

Phospholipase A2 from the rattlesnake Crotalus durissus terrificus was employed for the first time to test its enantioseletivity on the hydrolysis of different non-natural esters. It was observed that the structure of this small enzyme is restrictive in the choice of its lipase action with non-natural substrates. Two forms of the enzyme were used; free and as its cross-linked enzyme aggregate (CLEA). With all substrates, the free enzyme showed activity similar to the CLEA preparation. The advantage of the CLEA phospholipase is the possibility to reuse it in several consecutive reactions without a decrease of activity and selectivity with good but higher yields and ee than with the free enzyme.