Zinc-mediated reactions on salicylaldehyde for Botrytis cinerea control

Botrytis cinerea is a necrotrophic fungusth at a ffects various plant species.Chemical control is an ecessity and as much as possible,eco-friendly conditions and bioresources to obtain these chemicals should be used.In this context,a series of products w as obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea.     

A direct route to polythiophenes displaying lateral substituents: Easy one‐step synthesis and polymerization of thiophene monomers substituted by a dimethylenecarboxylate (CH2CH2COOR) appendage on the 3‐position

Thiophene monomers displaying a dimethylenecarboxylate (CH₂CH₂COOR) substituent on the 3‐position of the aromatic ring can be easily obtained and in one step from the electrochemically induced reaction of 3‐bromothiophene with the corresponding acrylate (CH₂?CHCOOR). The synthesis of the ethyl ester monomer, of related 2,5‐dihalogenothiophenes, and their polymerization are reported. Despite the surprisingly low solubilities displayed by the polymers, a full spectroscopic characterization could be performed and the data fully analyzed. Oxidative polymerizations (FeCl₃ or electropolymerization) yield a regioirregular polythiophene, with 60–70% of head‐to‐tail diads. Both experimental and theoretical results suggest that the nonconjugated ester plays a very minor role—if any—in the polymerizations under oxidative conditions, but has a significant influence on the polymer properties. Preliminary attempts to polymerize the dihalogenothiophenes under reductive conditions were hampered by the even lower solubilities exhibited by the regioregular oligomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Two new triterpenoid saponins from Pittosporum senacia Putterlick (Pittosporaceae)

From the branches of Pittosporum senacia Putterlick (Pittosporaceae), two new triterpenoid saponins, senaciapittosides A and B (1, 2), were isolated. Their structures were elucidated by extensive analysis of one‐ and two‐dimensional nuclear magnetic resonance spectroscopy, high‐resolution electrospray ionization mass spectrometry (HR‐ESIMS) and chemical evidence as 3‐O‐[β‐d ‐glucopyranosyl‐(1 → 2)]‐[α‐l ‐arabinopyranosyl‐(1 → 3)]‐[α‐l ‐arabinofuranosyl‐(1 → 4)]‐β‐d ‐glucuronopyranosyl oleanolic acid 28‐O‐β‐d ‐glucopyranosyl ester (1) and 3‐O‐[β‐d ‐glucopyranosyl‐(1 → 2)]‐[α‐l ‐arabinopyranosyl‐(1 → 3)]‐[α‐l ‐arabinofuranosyl‐(1 → 4)]‐β‐d ‐glucuronopyranosyl‐22‐O‐α‐l ‐arabinopyranosyl‐21‐acetoxy R1‐barrigenol (2). Compound 2 presents an unusual glycosylation at C‐22 of its aglycone. Copyright © 2012 John Wiley & Sons, Ltd.     

Back to BAC: Insights into Boronate Affinity Chromatography Interaction Mechanisms

Boronate affinity chromatography (BAC) is commonly used in sample preparation techniques for its specific selectivity for cis-diol-containing compounds. Various chromatographic materials based on phenyl-boronic acid (PBA) functionalization have been designed. This review aims to present the versatility of the underlying BAC mechanisms. The PBA moiety presents secondary/complementary/interfering interactions, i.e., hydrophobic, electrostatic and/or hydrogen-bonding interactions. The comprehensive understandings of these mechanisms are very helpful to manipulate separation selectivity, which is a key feature in biomolecular sample treatment. Each BAC interaction is reviewed and illustrated by specific examples. Special attention is given to the underlying role of PBA supports for sugars, glycans and glycoconjugates recognition.     

Revisiting Keteniminium Salts: More than the Nitrogen Analogs of Ketenes

Keteniminium salts are powerful electrophilic heterocumulene reagents well‐known for their selectivity and stereocontrol in [2+2] cycloadditions to olefins and carbonyl derivatives. Furthermore, they are readily accessible from stable and simple precursors under a variety of different conditions. Herein, we present the chemistry of keteniminium salts with the hindsight of time, describe preparation methods, recent [2+2] chemistry, mechanistic studies, and assorted applications that significantly extend the scope of utility of these unique electrophilic heterocumulenes.