AbstractAn unusual cobalt mediated [2 + 2 + 2] cycloaddition of yne‐ene‐yne diester substrates produces pentacyclic bis‐lactones.

Highly strained pentacyclic bis-lactones can be obtained by an unusual Co(I) catalyzed [2+2+2] cycloaddition of an yne–ene–yne diester substrate. These bis-lactones can be further transformed into tetraaryl N-hydroxyphthalimides which are potential aerobic oxidation organocatalysts.

Original and readily available 3,3′-diiodo-BINOL-fused maleimides were designed as hypervalent iodine(III) organocatalysts. They were used in intermolecular oxidation reactions at the α-position of ketones. The expected products were obtained with yields and enantiomeric excesses that were comparable to the best reported values achieved using structurally different organocatalysts.

The first synthesis of BINOL-fused maleimides has been developed. This new chiral scaffold is easily accessible from various BINOL analogues and 2,3-dihalomaleimide deriva-tives under basic conditions. It can be easily functionalized on the BINOL moiety and is an entry towards promising new classes of chiral organocatalysts and ligands.

The emission properties of a series of substituted 1,3-diarylisobenzofurans have been studied. Most compounds exhibit very intense emission in the nanosecond timescale at room temperature as well as at 77 K. The room temperature emission is attributed to the deactivation of a twisted intramolecular charge transfer excited state, based on its energy, shape and solvent dependence. The experimental results are strongly supported by a theoretical study on one representative compound. The DFT/TD-DFT calculations demonstrate that the initial excited state relaxes toward a twisted structure.

The one pot, in situ ortho-metalation/silylation of unprotected o-phthalic acids using lithium tetramethylpiperidide (LiTMP) and chlorotrimethylsilane is described. This method gives a straightforward access to silylated phthalic anhydrides. These can be easily converted into the corresponding silylated N-hydroxyphthalimide (NHPI) analogs, which are promising new aerobic oxidation catalysts.

AbstractThe reaction allows a general access to functionalized phthalimide structures and thus opens the way to new organocatalysts in areobic oxidation.

Functionalized tetraarylphthalimides or diarylphthalimides fused with an acenaphthene moiety have been prepared in one step from 2-bromomaleimide and tetraarylcyclopentadienones (tetracyclones) or 7,9-diaryl-8H-cyclopentacenaphthylene-8-ones (acecyclones). The reaction, involving a cycloaddition-decarbonylation-dehydrobromination sequence, gives high isolated yields and is compatible with the presence of various functional groups.

Various functionalized aryl boronic esters derived from hexylene glycol and pinacol were prepared in excellent yields according to a simple, safe procedure. The metal−halogen exchange reaction between iPrMgCl·LiCl and aryl iodides is performed at 0 °C in the presence of a cyclic borate ester (MPBOiPr or PinBOiPr); the organomagnesium intermediate is immediately trapped in situ so that no accumulation of hazardous reactive species can occur. The reaction is very selective, and particularly clean crude products are obtained. The scope of the procedure and the tuning of reaction parameters are investigated.

AbstractIn most cases, the reaction under microwave‐assisted conditions provides much higher yields of the products.

A chemoselective reduction of N-hydroxyphthalimides to phthalimides under mild conditions has been discovered. It involves reaction of an N-hydroxyimide with bis(pinacolato)diboron in the presence of a base. Other easily reducible functional groups, such as iodo, nitro, or azido groups are unaffected. Alternatively, such functional groups may be selectively reduced without affecting the N-hydroxyimide moiety using a set of classical conditions.

The ecotoxicological impact of nitrate‐induced photodegradation products of diuron and chlorotoluron was studied through monospecific biotests conducted in conjunction with experiments in outdoor aquatic mesocosms. Organisms representing three trophic levels were used: two heterotrophic microorganisms, the luminescent bacterium Vibrio fischeri and the ciliated protozoa Tetrahymena pyriformis , and one metazoa, the gastropod Lymnaea stagnalis . Among the variety of the phenylurea photoproducts, the N ‐formylated ones appeared clearly more toxic than the parent compounds towards the microorganisms, whereas the nitroderivatives showed a similar toxicity. Using photodegraded solutions of diuron, toxicity was maintained or even increased during disappearance of the initial herbicide, demonstrating that some of the photoproducts may have an impact additively or in synergy. Enzymatic biomarker assays performed on Lymnaea stagnalis exposed under monospecific conditions showed significant effects, due to the combination of nitrate with the pesticide and its photoproducts. A positive impact on snail fecundity was observed with chlorotoluron both under monospecific laboratory and integrated mesocosm conditions. Oviposition stimulation took place when first‐ and second‐generation photoproducts were predominant. Environ. Toxicol. Chem. 2010;29:2644–2652. © 2010 SETAC

Time-of-flight secondary ion mass spectrometry imaging has been used to map flavonoids in fresh seed sections of peas (Pisum sativum) and Arabidopsis thaliana. While for peas a very simple preparation method derived from mammalian tissue imaging could be utilized, several preparation methods had to be tested for the A. thaliana seeds before obtaining tissue sections on which the diagnostic ions were not delocalized. For such small and stiff biological material, none of the methods currently used in histology or scanning electron microscopy could be transferred to mass spectrometry imaging. Only the embedding of the fresh seeds in a polyester resin, followed by the analysis of the block after having obtained a flat surface section with a diamond blade, gave sensitive and reproducible results. Several flavonoid ions have been detected in the sections, showing increased concentrations of flavonoids in the seed coats. The method was finally applied to confirm the variations in the flavonoid content of seeds from different A. thaliana mutants.

Variously substituted 1,3-diarylisobenzofurans have been regiospecifically prepared via palladium-and rhodium-catalysed reaction of functionalised boronic acids onto o-acylbenzaldehydes. Rhodium catalysis has furthermore been improved using microwave activation. Thus, isobenzofurans containing aryl groups substituted by halogens, unprotected amine, alcohol and even aldehyde groups, have been obtained directly in good to satisfactory yields. Divergent results have been observed when palladium-, rhodium- and MW-activated rhodium-catalysis was applied to the reaction of phenylboronic acid with an iodinated o-acylbenzaldehyde, leading principally to Suzuki coupling product and/or to iodinated isobenzofuran.

Reported is the synthesis of isobenzofurans, involving the catalytic addition of an arylboronic acid to an ortho-keto aldehyde, followed by ring closure and elimination of water. Several different catalytic systems were implemented, with varying degrees of success. The use of microwave heating was extremely useful in certain cases, most notably for boronic acids containing reactive or sterically hindered functional groups. In one particular case (R = I, Ar = Ph) the use of microwave heating changed the path of the reaction and the isobenzofuran product was obtained in 70% yield, in place of the Suzuki product, which was formed under standard heating conditions in 74% yield. This change of reaction with microwave heating is suggested to be due to the formation of a different catalytic system from that of the conventional heating conditions.

The nitrate-induced photodegradation of chlorotoluron was demonstrated to occur efficiently in natural water through two series of experiments in outdoor aquatic mesocosms. During the first campaign, it was shown that the pesticide degradation kinetics was clearly dependent on nitrate concentration. This parameter also influenced the accumulation of the first- and second-generation byproducts, including predominantly N-terminus oxidation products and nitro-derivatives of the phenyl ring. The latter compounds, specific to the NO3- -induced photoprocess, appeared particularly abundant as compared to laboratory-simulated sunlight irradiation conditions. During the second campaign, a dual day-night sampling was achieved, which demonstrated the almost exclusive role of photodegradation versus biodegradation.

BACKGROUND The metabolism of cymoxanil [1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea] and fungicidal cyanooxime analogues was monitored on three phenotypes of Botrytis cinerea Pers. ex Fr. differing in their sensitivity towards cymoxanil. For this purpose, labelled [2-(14)C]cymoxanil was added either to the culture medium of these strains or to its cell-free extract. RESULTS In the culture medium of the most sensitive strain, four main metabolites were detected. Three were isolated and identified. Cymoxanil was quickly metabolised by at least three concurrent enzymatic pathways: (i) cyclisation leading, after hydrolysis, to ethylparabanic acid, (ii) reduction giving demethoxylated cymoxanil, (iii) hydrolysis followed by reduction and then acetylation leading to N-acetylcyanoglycine. In the cell-free extract of the same strain, only the first and the second of these enzymatic reactions occurred. By comparing the metabolic profile of the most sensitive strain with that of the less sensitive ones, it was shown that the decrease in sensitivity to cymoxanil correlates with a reduced acetylcyanoglycine formation. Among all metabolites, only N-acetylcyanoglycine is active against the most sensitive strain. Moreover, in a culture of this strain, two other fungicidal cyanooximes were also metabolised into this metabolite. CONCLUSION The formation of N-acetylcyanoglycine may play an important role in the fungitoxicity of cymoxanil and cyanooxime derivatives.

Described is the convenient, efficient regiospecific synthesis of functionalized 1,3-diarylisobenzofurans by chemoselective addition of arylmagnesium reagents to ortho-aroylbenz­aldehydes, which are obtained by an interesting lead tetraacetate oxidation-rearrangement of N-aroylhydrazones of substituted salicylaldehydes (A. Kotali, P. G. Tsoungas Tetrahedron Lett. 1987, 28, 4321).