Efficient Synthesis of Pharmaceutically Relevant Prochiral Heterocyclic Aminoketones

In this work, we report a practical method for alkylation of saturated heterocycles with chloroacetone yielding prochiral heterocyclic ketones, including previously not described molecules. The desired building blocks were obtained with high yields in hydrochloric salt forms, without the need for chromatographic purification

Microfluidic Multiple Chamber Chip Reactor Filled with Enzyme-Coated Magnetic Nanoparticles

In this chapter, a novel microfluidic device (MagneChip) is described which comprises microliter volume reaction chambers filled with magnetically fixed enzyme-coated magnetic nanoparticles (ecMNPs) and with an in-line UV detector. In the experiments, MNPs with phenylalanine ammonia-lyase (PAL)—an enzyme which catalyzes the deamination of l-phenylalanine (Phe) to (E)-cinnamate in many organisms—immobilized on the surface were applied as biocatalyst to study the characteristics of the MagneChip device. In the reaction chambers of this microfluidic device, the accurate in situ quantization of the entrapped MNPs was possible using a resonant coil magnetometer integrated below the chambers. Computational fluid dynamics (CFD) calculations were used to simulate the flow field in the chambers. The enzyme-catalyzed biotransformations could be performed in the chip with excellent reproducibility and of repeatability. The platform enabled fully automatic multiparameter measurements with a single biocatalyst loading of about 1 mg PAL-ecMNP in the chip. A study on the effect of particle size and arrangement on the catalytic activity revealed that the mass of ecMNPs fixed in the chamber is independent of the particle diameter. Decreasing the particle size resulted in increasing catalytic activity due to the increased area to volume ratio. A binary mixture of particles with two different particle sizes could increase the entrapped particle mass and further the catalytic activity compared to the best uniform packing. The platform enabled a study of biotransformation of l-phenylalanine and five unnatural substrates by consecutive reactions using same PAL-ecMNP loading. With the aid of the platform, we first demonstrated that PAL can catalyze the ammonia elimination from the noncyclic propargylglycine as substrate

From Synthetic Chemistry and Stereoselective Biotransformations to Enzyme Biochemistry – The Bioorganic Chemistry Group at the Budapest University of Technology and Economics

The activity of Bioorganic Chemistry Group (BCG) within Department of Organic Chemistry and Technology at Budapest University of Technology and Economics is related to various areas of synthetic chemistry, biotechnology and enzymology. This review gives an overview on the research activity of the group covering development of synthetic organic chemistry methods; stereoselective biotransformations with lipases, ammonia-lyases and further biocatalysts in batch and continuous-flow reactions; novel enzyme immobilization methods; and enzyme structural and mechanistic studies by experimental and computational techniques

Copper(II) Fluoride a New Efficient Promoter of Chan-Lam-Evans Coupling

The Chan-Lam-Evans coupling is the copper(II) acetate promoted reaction of phenols and boronic acids producing diaryl ethers. In this paper a modification of the original reaction is reported using copper(II) fluoride reagent which gives higher yields than copper(II) acetate. The most significant increase in yield was observed in formation of sterically hindered phenols. We hypothesize that fluoride ions help to cleave the boron-carbon bond. The novel method is suitable for selective, efficient and economical synthesis of diaryl ether compounds under mild conditions

Characterization of Yeast Strains with Ketoreductase Activity for Bioreduction of Ketones

This study describes six yeast strains for stereoselective ketone reductions. The reaction conditions for the yeast strains (Pichia carsonii, Lodderomyces elongisporus, Candida norvegica, Candida guillermondi, Debaromyces fabryi and Candida parapsilosis) were optimized in a design of experiments for three ketones of different properties. The pH tolerance, temperature stability and productivity of the bioreductions with lyophilized cells of the yeast strains were characterized. In several cases, the optimized bioreductions resulted in enantiopure alcohols (ee > 99 %) with conversions ranging from moderate to excellent

Lipase-catalyzed kinetic resolution of 1-(2-hydroxycyclohexyl)indoles in batch and continuous-flow systems

The lipase catalyzed kinetic resolution of three trans-1-(2-hydroxycyclohexyl)-indoles in both batch and continuous flow systems is reported. Ring opening of cyclohexene oxide by the corresponding indole followed by enzymatic acylation with vinyl acetate resulted in novel, highly enantioenriched indole-substituted cyclohexanols and cyclohexyl acetates. The effect of the temperature on enantiomeric ratio (E) and productivity (specific reaction rate, rflow) in the continuous-flow mode acylation was studied at analytical scale in the 0–70 °C range. Preparative scale kinetic resolution of the three indole derivatives was performed in mixed continuous- and recirculation-flow mode resulting in almost complete conversion and good to excellent enantiomeric purity of the products

Diisopropyl Malonate as Acylating Agent in Kinetic Resolution of Chiral Amines with Lipase B from Candida antarctica

Activity of diisopropyl malonate (2) as a novel acylating agent was investigated in kinetic resolution (KR) of various racemic amines [(±)-1a-d] catalyzed by lipase B from Candida antarctica. Diisopropyl malonate (2) proved to be effective acylating agent with four racemic amines [(±)-2-aminoheptane, (±)-1-methoxy-2-propylamine, (±)-1-phenylethylamine and (±)-4-phenylbutan-2-amine; (±)-1a-d, respectively] selected for this study. The lipase-catalyzed acylation of the amines (±)-1a-d with 2 proceeded with good conversions (44.9–52.1%) and provided the expected (R)-amides [(R)-3a-d] in moderate to excellent yields (51–98%) with high enantiomeric excess (ee(R)-3a-d 92.0–99.9%) after 4 h reaction time under mild reaction conditions in batch mode. The best conversion (50%) combined with high enantiomeric purity (ee(R)-2d > 99%ee) was achieved in the KR from racemic 2-aminoheptane (±)-1a. The four novel (R)-amides [(R)-3a-d] were isolated and properly characterized

A NOVEL PHENYLALANINE AMMONIA-LYASE FROM KANGIELLA KOREENSIS

This study describes cloning of the gene encoding a novel phenylalanine ammonia-lyase from Kangiella koreensis (KkPAL) into pET19b expression vector. Optimization of protein expression and purification conditions yielded 15 mg pure soluble protein from one liter of E.coli culture. Enzymatic activity measurements of the ammonia elimination reaction from different natural aromatic amino acids proved the protein to be a phenylalanine ammonia-lyase. The isolated protein showed remarkably high, 81.7 °C melting temperature, making it especially suitable for biocatalytic applications