A novel lipase enzyme panel exhibiting superior activity and selectivity over lipase B from Candida antarctica for the kinetic resolution of secondary alcohols

A novel, commercially available lipase enzyme panel performing kinetic bioresolutions of a number of secondary alcohols is reported. The secondary alcohols that have been chosen are known from the literature to be particularly challenging substrates to resolve. Following initial screening, four co-solvents were investigated for each lead enzyme in an effort to assess their tolerance to common organic solvents. The superiority of these novel enzymes over lipase B from Candida antarctica (CALB) has been demonstrated.     

Recent Trends in Enzyme Immobilization—Concepts for Expanding the Biocatalysis Toolbox

Enzymes have been exploited by humans for thousands of years in brewing and baking, but it is only recently that biocatalysis has become a mainstream technology for synthesis. Today, enzymes are used extensively in the manufacturing of pharmaceuticals, food, fine chemicals, flavors, fragrances and other products. Enzyme immobilization technology has also developed in parallel as a means of increasing enzyme performance and reducing process costs. The aim of this review is to present and discuss some of the more recent promising technical developments in enzyme immobilization, including the supports used, methods of fabrication, and their application in synthesis. The review highlights new support technologies such as the use of well-established polysaccharides in novel ways, the use of magnetic particles, DNA, renewable materials and hybrid organic–inorganic supports. The review also addresses how immobilization is being integrated into developing biocatalytic technology, for example in flow biocatalysis, the use of 3D printing and multi-enzymatic cascade reactions.     

Potassium N‐Iodo p‐Toluenesulfonamide (TsNIK,Iodamine‐T): A New Reagent for the Oxidation of Hydrazones to Diazo Compounds

A new reagent for the oxidation of hydrazones to diazo compounds is described. N‐Iodo p‐toluenesulfonamide (TsNIK, iodamine‐T) allows the preparation of α‐diazoesters, α‐diazoamides, α‐diazoketones and α‐diazophosphonates in good yield and in high purity after a simple extractive work‐up. α‐Diazoesters were also obtained in high yield from the corresponding ketones through a one‐pot process of hydrazone formation/oxidation.     

Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene OH Insertion Reaction

Copper‐ or rhodium‐catalyzed reactions of diazocarbonyl compounds with β‐hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single‐step process starts as a carbene O? H insertion reaction, but is diverted by an intramolecular aldol reaction.     

Total Synthesis of the Posttranslationally Modified Polyazole Peptide Antibiotic Plantazolicin A

The power of rhodium–carbene methodology in chemistry is demonstrated by the synthesis of a structurally complex polyazole antibiotic. Plantazolicin A, a novel soil‐bacterium metabolite, comprises a linear array of 10 five‐membered rings in two pentacyclic regions that derive from ribosomal peptide synthesis followed by extensive posttranslational modification. The compound possesses potent antimicrobial activity, and is selectively active against the anthrax‐causing organism. A conceptually different synthesis of plantazolicin A is reported in which the key steps are the use of rhodium(II)‐catalyzed reactions of diazocarbonyl compounds to generate up to six of the seven oxazole rings of the antibiotic. NMR spectroscopic studies and molecular modeling reveal a likely dynamic hairpin conformation with a hinge region around the two isoleucine residues. The compound has modest activity against methicillin‐resistant Staphylococcus aureus (MRSA).     

Highly stereoselective biocatalytic reduction of alpha-halo ketones

The use of recombinant carbonyl reductase biocatalysts for the reduction of alpha-halo ketone intermediates to their corresponding alpha-halo alcohols has been investigated. The alpha-halo alcohol is obtained in good yield from the corresponding ketone in a stereoselective manner.     

Zur Bestimmung des Wasserstoffsuperoxyds, der Alkalipercarbonate und der Persulfate

Ohne Zusammenfassung