Marek Koprowski

Germination induction of dormant Avena fatua caryopses by KAR1 and GA3 involving the control of reactive oxygen species (H2O2 and O2−) and enzymatic antioxidants (superoxide dismutase and catalase) both in the embryo and the aleurone layers

Avena fatua L. caryopses did not germinate at 20 °C in darkness because they were dormant. However, they were able to germinate in the presence of karrikinolide (KAR1), a key bioactive compound present in smoke, and also in the presence of gibberellin A3 (GA3), a commonly known stimulator of seed germination. The aim of this study was to collect information on a possible relationship between the above regulators and abscisic acid (ABA), reactive oxygen species (ROS) and ROS scavenging antioxidants in the regulation of dormant caryopses germination. KAR1 and GA3 caused complete germination of dormant A. fatua caryopses. Hydrogen peroxide (H2O2), compounds generating the superoxide (O2(·-)), i.e. menadione (MN), methylviologen (MV) and an inhibitor of catalase activity, aminotriazole (AT), induced germination of dormant caryopses. KAR1, GA3, H2O2 and AT decreased ABA content in embryos. Furthermore, KAR1, GA3, H2O2, MN, MV and AT increased α-amylase activity in caryopses. The effect of KAR1 and GA3 on ROS (H2O2, O2(·-)) and activities of the superoxide dismutase (SOD) and catalase (CAT) were determined in caryopses, embryos and aleurone layers. SOD was represented by four isoforms and catalase by one. In situ localization of ROS showed that the effect of KAR1 and GA3 was associated with the localization of hydrogen peroxide mainly on the coleorhiza. However, the superoxide was mainly localized on the surface of the scutellum. Superoxide was also detected in the protruding radicle. Germination induction of dormant caryopses by KAR1 and GA3 was related to an increasing content of H2O2, O2(·-)and activities of SOD and CAT in embryos, thus ROS homeostasis was probably required for the germination of dormant caryopses. The above regulators increased the content of ROS in aleurone layers and decreased the activities of SOD and CAT, probably leading to the programmed cell death. The presented data provide new insights into the germination induction of A. fatua dormant caryopses by KAR1 and also by GA3. In A. fatua, KAR1 or GA3 is included in the induction germination of dormant caryopses through regulation level of ABA in embryos and ROS-antioxidant status both in embryos and aleurone layers.

New enantiopure cyclic β-iminophosphine ligands: applications in Pd-catalyzed asymmetric allylic substitution

New enantiopure cyclic β-iminophosphines were applied as ligands in Pd-catalyzed asymmetric allylic substitution reactions.

A novel displacement route to P-chiral phosphine oxides of high enantiomeric purity

Reaction of (R)-(1-chlorovinyl)methylphenylphosphine oxide with aryl and alkenyl Grignard reagents result in highly stereoselective displacement of the halovinyl group and afford virtually enantiomerically pure arylmethylphenyl and alkenylmethylphenylphosphine oxides of inverted configuration at phosphorus.

Synthesis of enantiomerically pure styryl and dienyl phosphine oxides via Pd-catalyzed Heck coupling reaction

Abstract (S)-Methylphenylvinylphosphine oxide ( 1 ) undergoes facile Pd-catalyzed coupling with functionalized aryl and vinyl halides to provide new enantiomerically pure styryl and dienyl phosphine oxides including also the corresponding symmetrical and nonsymmetrical bisphosphine derivatives.

Stereospecific [2,3] sigmatropic rearrangement of allylic sulfoxides and selenoxides. Synthesis of novel polycyclic allylic alcohols and α-hydroxy ketones

Abstract A stereospecific [2,3] sigmatropic rearrangement of functionalized bi- or tricyclic allylic sulfoxides and selenoxides as a route to new allylic alcohols and their transformation into the corresponding α-hydroxy ketones having a defined stereochemistry is described. It has been demonstrated that cycloadducts, derived from [4+2] cycloaddition of (Z)-1-alkylthio-2-diethoxyphosphoryloxy-1,3-dienes to a various dienophiles, are versatile synthons carrying much structural and stereochemical information.

Enantioselective desymmetrization of a phospholene meso-epoxide

Cinchona alkaloids serve as effective chiral bases in the enantioselective rearrangement of 3-phospholene epoxide. The reaction results in the formation of a P,C-chirogenic 3-hydroxy-2-phospholene derivative with up to 52% e.e. A stereochemical course for the epoxide rearrangement involving anti-β-proton abstraction is implied.

The Diels-Alder Reactions of (Z)-1,2-Diheterosubstituted-1,3-Dienes. Sulfur as a Regiochemical Control

Abstract Thermal and Lewis acid catalysed cycloadditions of dienes 1 to dienophiles proceed with complete regio-and stereo-selectivity and provide a route to the cyclic enones.

Synthesis of (z)-1,2-diheterosubstituted-1,3-dienes. novel annelating agents

Abstract Readily available thiophosphates containing an α,β-unsaturated moiety have been efficiently converted into the novel (Z)-1,2-diheterosubstituted-1,3-dienes by treatment with sodium hydride followed by the corresponding electrophile

Direct chromatographic resolution of P-chiral phosphinoylethenes on a chiral stationary phase containing N,N′-(3,5-dinitrobenzoyl)-trans-1,2-diaminocyclohexane as selector

Abstract A π-acidic, totally synthetic HPLC chiral stationary phase is used to separate the enantiomers of a wide range of unsaturated P-chiral phosphine oxides. It allows for fast, sensitive and accurate e.e. determinations and secures easy access to optically pure enantiomers by chromatography on preparative columns.

Synthesis of 1-indanones with a broad range of biological activity

This comprehensive review describes methods for the preparation of 1-indanones published in original and patent literature from 1926 to 2017. More than 100 synthetic methods utilizing carboxylic acids, esters, diesters, acid chlorides, ketones, alkynes, alcohols etc. as starting materials, have been performed. This review also covers the most important studies on the biological activity of 1-indanones and their derivatives which are potent antiviral, anti-inflammatory, analgesic, antimalarial, antibacterial and anticancer compounds. Moreover, they can be used in the treatment of neurodegenerative diseases and as effective insecticides, fungicides and herbicides.