We studied the effect of Silicon (Si) on Casparian band (CB) development, chemical composition of the exodermal CB and Si deposition across the root in the Si accumulators rice and maize and the Si non-accumulator onion. Plants were cultivated in nutrient solution with and without Si supply. The CB development was determined in stained root cross-sections. The outer part of the roots containing...

A green and efficient one-pot three component reaction of 4-hydroxycoumarin or 1,3-dimethylbarbutyric acid, aryl glyoxals and amides (thioacetamide) has been developed in the presence of BF3- SiO2 nanoparticles in water. This method has several advantages such as high to excellent product yields in short reaction time, atom economy, environment friendly, reusable catalyst and no need for chroma...

Methods were developed and optimized for the preparation of the 2,3-cis- and the 10,11-cis-isomers of silybin by the Lewis acid catalyzed (BF3∙OEt2) isomerization of silybins A (1a) and B (1b) (trans-isomers). The absolute configuration of all optically pure compounds was determined by using NMR and comparing their electronic circular dichroism data with model compounds of known absolute config...

Aldehydes undergo a smooth coupling with (E/Z)-non-3-en-8-yn-1-ol in the presence of 10 mol% of CuX and BF3·OEt2 under mild conditions to produce a novel class of octahydrocyclohepta[c]pyran-6(1H)-one derivatives in good yields with excellent diastereoselectivity through a sequential Prins/alkynylation/hydration. This is the first report on the termination of Prins cyclization with a tethered a...

Hydrocarbon deposits, often found in oil or polymer industries, are very difficult to detect by the usual inspection techniques of gamma radiography or x-ray radiography methods. The density and atomic number of pipe walls are much higher than that of the scale, therefore, most of the attenuation of gamma rays or x-rays, takes place in the iron, and only a negligible fraction in the scale. This...

A novel synthetic strategy leading to 3-acetamido-3-deoxy-D-psicofuranose 9 is presented. The latter compound, after some manipulations, was transformed into fully protected 3-acetamido-3-deoxy-D-psicofuranose 11 as a potential substrate for the synthesis of N-acetylglucosaminyltransferase inhibitors designed by computational methods. After the attempted thioglycosylation of 11 with EtSH in the...

Derivatives of the fully twisted bicyclic amide 7-hypoquinuclidone are synthesized using a Schmidt-Aubé reaction. Their structures were unambiguously confirmed by X-ray diffraction analysis and extensive spectroscopic characterization. Furthermore, the stability and chemical reactivity of these anti-Bredt amides are investigated. 7-Hypoquinuclidonium tetrafluoroborate is shown to decompose to a...