Biotransformations of 2-hydroxy-2-(ethoxyphenylphosphinyl)acetic acid and the determination of the absolute configuration of all isomers

Lipase-Catalyzed Kinetic Resolution of Dimethyl and Dibutyl 1-Butyryloxy-1-carboxymethylphosphonates

The main objective of this study is the enantioselective synthesis of carboxyhydroxyphosphonates by lipase-catalyzed reactions. For this purpose, racemic dimethyl and dibutyl 1-butyryloxy-1-carboxymethylphosphonates were synthesized and hydrolyzed, using a wide spectrum of commercially available lipases from different sources (e.g., fungi and bacteria). The best hydrolysis results of dimethyl 1-butyryloxy-1-carboxymethylphosphonate were obtained with the use of lipases from Candida rugosa, Candida antarctica, and Aspergillus niger, leading to optically active dimethyl 1-carboxy-1-hydroxymethylphosphonate (58%–98% enantiomeric excess) with high enantiomeric ratio (reaching up to 126). However, in the case of hydrolysis of dibutyl 1-butyryloxy-1-carboxymethylphosphonate, the best results were obtained by lipases from Burkholderia cepacia and Termomyces lanuginosus, leading to optically active dibutyl 1-carboxy-1-hydroxymethylphosphonate (66%–68% enantiomeric excess) with moderate enantiomeric ratio (reaching up to 8.6). The absolute configuration of the products after biotransformation was also determined. In most cases, lipases hydrolyzed (R) enantiomers of both compounds.

Intramolecular Hydrogen Bonds in Selected Aromatic Compounds: Recent Developments

A review of intramolecular hydrogen bonding in ortho-hydroxyaryl Schiff bases, ortho-hydroxyaryl Mannich bases, dipyrrins, ortho-hydroxyaryl ketones, ortho-hydroxyaryl amides, and 4-Bora-3a,4a-diaza-s-indacene (BODIPY) dyes with tautomeric sensors as substituents is presented in this paper. Ortho-hydroxy Schiff and Mannich base derivatives are known as model molecules for analysing the properties of intramolecular hydrogen bonding. The compounds under discussion possess physicochemical features modulated by the presence of strong intramolecular hydrogen bonds. The equilibrium between intra- and inter-molecular hydrogen bonds in BODIPY is discussed. Therefore, the summary can serve as a knowledge compendium of the influence of the hydrogen bond on the molecular properties of aromatic compounds.

Fungal synthesis of chiral phosphonic synthetic platform - Scope and limitations of the method

Chiral hydroxyphosphonates due to their wide range of biological properties are industrially important chemicals. Chemical synthesis of their optical isomers is expensive, time consuming and not friendly to the environment, so biotransformations are under consideration. Among others, these compounds act as enzymes inhibitors. This makes the bioconversions of phosphonates, especially scaling experiments, hard to perform. Biocatalysis is one of the methods that can be applied in synthesis of optically pure compounds. To increase the efficiency of the process with whole cell biocatalysts, it is essential to ensure optimal reaction conditions that minimize cellular stress and can enhance the metabolic activity of cells. The present investigation focuses on the scaling up of the kinetic resolution of racemic mixture of 2-butyryloxy-2-(ethoxy-P-phenylphosphinyl)acetic acid, applying free and immobilized form of the fungal biocatalysts and two operation systems: shake flask and recirculated fixed-bed batch reactor. Protocols of effective mycelium immobilization on polyurethane foams were set for T. purpurogenus IAFB 2512, F. oxysporum, P. commune. The best results of biotransformation were obtained with the immobilized P. commune in the column recirculated fixed-bed batch reactor. The conversion reaches 56% (maximal for the kinetic process) and the enantiomeric enrichment of the isomers mixture ranges between 82 and 93% (93% for ester of R_P,R conformation). All biocatalysts exhibit S_P-preference toward tested compound, what is essential because of importance of the phosphorus atom chirality for its biological activity.