Ülo Lille

New antiproliferative 9,11-secosterol from soft coral gersemia fruticosa

A new highly antiproliferative 9,11-secosterol 1 was isolated from the White Sea soft coral Gersemia fruticosta. The structure was established

The tetrahydropyranyl-protected mandelic acid: a novel versatile chiral derivatising agent

Abstract A simple synthesis of (2R)-2-phenyl-2-[(2S)-tetrahydro-2-pyranyloxy]ethanoic acid, a versatile chiral derivatising agent (CDA), is proposed. The derivatisation of secondary alcohols aimed at the absolute configurational assignment, determination of enantiomeric purity as well as semipreparative resolution is described.

Lipase action on some non-triglyceride substrates

Approaches for improving methodologies of kinetic resolution of enantiomers as well as of regioselective protection of functional groups of complex chiral molecules involving lipase-catalytic reactions are highlighted. Decyclization of hemiacetals by lipase as well as exclusive pathways of lipase-catalyzed derivatization of prostanoids are brought out. Lipase-triggered cascade-reactions are noticed.

Short Synthesis of Novel 9,11-Secosterols

Abstract Starting from ergosterol two novel 9,11-secosterols with modified side chains (1a) and (1c) were synthesized via eight main transformations.

Lipase-catalysed enantioselective hydrolysis of bicyclo[3.2.0]heptanol esters in supercritical carbon dioxide

Abstract The esters derived from 2-exo-bromo-3-endo-hydroxybicyclo[3.2.0]heptan-6-one were treated with Lipolase under hydrolytic conditions in supercritical carbon dioxide (SCCO2). All the esters tested gave access to optically active material (e.e. 50–90%). The esters with an additional keto or hydroxy group were hydrolysed to 35–40% conversion while nonpolar lipophilic substrates gave poor conversions (3–5%) under the same conditions.

Lipase-catalysed enantioselective hydrolysis: Interpretation of the kinetic results in terms of frontier orbital localisation

Abstract The initial velocities of the enantioselective hydrolysis of the esters derived from mono- and bicyclic alcohols and hemiacetals catalysed by Lipolase™ in water have been determined. The differences in hydrolysis rates within groups of sterically similar substrates have been interpreted in terms of frontier orbital localisation.

A Mesoscale Simulation of the Morphology of the PEDT/PSS Complex in the Water Dispersion and Thin Film: the Use of the MesoDyn Simulation Code

intrinsically conducting polymer. Its complex with polystyrene sulfonic acid (PSS) attracts general interest ([1] and citations therein). The dispersion of the PEDT/PSS complex is usually prepared by an oxidative oligomerization of ethylenedioxythiophene (EDT) in the water solution in the presence of the soluble charge balancing and stabilizing polyanion of PSS. The oxidation (doping) process controls the number of the supposed ionic groups but the positions of the latter are random and not controlled (Fig. 1). The electrophoretic and viscosity characteristics of the swollen particles present in the dispersion are similar to those of nonstoichiometric polyelectrolyte complexes [2].

Thermomyces lanuginosus Lipase with Closed Lid Catalyzes Elimination of Acetic Acid from 11‐Acetyl‐Prostaglandin E2

A lipase may catalyze either one or more of the three reactions of 11‐acetyl‐prostaglandin E2 in methanol‐containing reaction medium: esterification, deacetylation, and/or elimination. The catalytic performance depends on the lipase and on the methanol content. An increase in the methanol concentration in benzene from 5 % to 95 % leads to the exclusive switch of reactions from esterification to elimination catalyzed by Thermomyces lanuginosus lipase (TLL). To explain the switch, molecular dynamics simulations of solvation of TLL in benzene and in methanol were performed. Solvation in methanol leads to the closing of the lid. The repositioning of the oxyanion hole towards the catalytic triad blocks the catalysis of ester synthesis whereas enabling TLL to act as an acetyl‐β‐ketol eliminase. In benzene the lid is open, allowing esterification to occur. Docking analysis of 11‐acetyl‐prostaglandin E2 into the active site of the solvated TLL structures suggested the occurrence of reactions in accordance with the experiment.

An Assessment of Alternative Low Level Calculation Methods for the Initial Selection of Conformers of Diastereomeric Esters

Critical assessment of performance of alternative molecular modeling methods depending on a specific object and goal of the investigation is a question of continuous interest. This prompted us to demonstrate the origin of the guidelines we have used for a rational choice and use of a proper low level calculation method (LLM) for an initial geometry optimization of generated conformers, with the aim of selecting a set for further optimization. What was performed herein was a comparison of LLMs: MM3, MM

Correlation of the morphology and electrical conductivity in thin films of PEDT/PSS complex: an integrated meso-scale simulation study

Using an integrated meso-scale simulation methodology, the morphology and electrical conductivity relationship of the poly(ethylene-dioxy)thiophene/poly-styrenesulphonate (PEDT/PSS) complex in the range of PSS/PEDT mass ratios 1.4–20 has been established. The morphology presented as a density field has been generated by dynamic density field theory-based MesoDyn simulation code for all systems taking into account the substrate surface effect. Generated anisotropic morphologies have been characterised by the modified anisotropy parameter Q i and Q Di values indicating the anisotropy along the system diagonals and coordinates, respectively. Based on the hopping mechanism of the conductivity, the values of the percolation-related critical parameter are identified and correlated with the macroscopic in-plane (∥) and out-of-plane ( ⊥ ) electrical conductivities, relative to the substrate surface. These macroscopic conductivities are also calculated accurately by applying the Kirchoff laws to the respective random resistor networks. The results are in a reasonable agreement with the available experimental data.