1829-60-3

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The biological activity of alcohol and epoxide groups containing bicyclic skeletal structures was investigated in terms of antibiotic and toxic effects at cellular level. The present protocol, which utilizes readily available starting materials and mild reaction conditions, provides an attractive approach to a series of functionalized bicyclic alcohol and epoxide derivatives with promising biological applications. In this protocol, while some of the bicyclic compounds were synthesized as in the literature, the other bicyclic compounds were synthesized by new synthetic methods. The antibiotic and toxic properties of the synthesized bicyclic compounds were investigated, and some of their biological activities were tested in prokaryotic and eukaryotic systems. (rac)-Dimethyl 3,8-dioxatricyclo[3.2.1.02,4]oct-6-ene-6,7-dicarboxylate, one of the synthesized molecules that showed antibiotic activity, was tested in two different living systems (prokaryotic and eukaryotic) in terms of biological and toxic effects at cellular level using a peripheral lymphocyte culture assay. Mitotic index for this compound was calculated in lymphocyte cultures.

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A palladium-catalyzed ortho-silylation of aryl iodides/arylsilylation of oxanorbornadiene/retro-Diels-Alder domino reaction was developed. Such a transformation provides access to various functionalized (Z)-β-substituted vinylsilanes with exclusive selectivity using hexamethyldisilane as a bis-silylation reagent and 2,3-dicarbomethoxy-7-oxanorbornadiene (ONBD) as an ortho-C-H activator and ethylene surrogate. A variety of (Z)-β-substituted vinylgermanes and (Z)-β-substituted vinylstannanes were also obtained under mild reaction conditions. This atom-economical, stereoselective, and scalable approach is compatible with a diverse range of readily available functionalized aryl iodides.

A novel palladium-catalyzed interannular selective C-H silylation of 1,1′-biaryl-2-acetamides is described. The combination of palladium catalyst with copper oxidant enables meta- or ortho-selective C-H silylation by employing hexamethyldisilane as a trimethylsilyl source, which relies on the control of NBE derivatives as a switch, thus providing straightforward access to divergent silicon-containing 1,1′-biaryl-2-acetamides.

Combined use of oxorhenium catalysts with triphenyl phosphite as an oxygen acceptor allowed efficient deoxygenative aromatization of oxabicyclic dienes. The reaction proceeded under neutral conditions and was compatible with various functional groups. Combining this deoxygenation with regioselective bromination and trapping of the generated aryne with furan resulted in benzannulative π-extension at the periphery of the PAHs. This enabled direct use of unfunctionalized PAHs for extension of π-conjugation. Iteration of the transformations increased the number of fused-benzene rings one at a time, which has the potential to alter the properties of PAHs by fine-tuning the degree of π-conjugation, shape, and edge topology.

The present invention is directed to a method for preparing a final phenolic product from biomass comprising the steps of providing a furanic compound obtainable from biomass; reacting the furanic compound with a dienophile to obtain a phenolic compound; reacting the phenolic compound further to obtain the final phenolic product.

Like azides, diazoacetamides undergo 1,3-dipolar cycloadditions with oxanorbornadienes (OND) in a reaction that is accelerated by the relief of strain in the transition state. The cycloaddition of a diazoacetamide with unstrained ethyl 4,4,4-trifluoro-2-butynoate is, however, 35-fold faster than with the analogous OND because of favorable interactions with the fluoro groups. Its rate constant (k = 0.53 M-1 s-1 in methanol) is comparable to those of strain-promoted azide-cyclooctyne cycloadditions.

Abstract The reaction between 2,3-dimethyl-1,3-butadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate is efficiently achieved with small amounts of catalyst, i.e. phenol, AcOH, nafion, and β-cyclodextrin. Exo-diastereoselective cycloa

Intramolecular photoinduced cyclizations are investigated in photoprecursors assembled in a modular fashion via a Diels-Alder reaction of acetylenic dienophiles with subsequent Michael additions of aromatic ketones to install a chromophore capable of initiating Paternò-Büchi cycloadditions or radical cyclization cascades. The protolytic oxametathesis in these systems allows for rapid access to novel polycyclic scaffolds decorated by formyl groups and carboxylates suitable for subsequent modifications. In conformationally constrained photoprecursors, a radical rearrangement takes place resulting in intramolecular 1,3-diradical cyclopentanation of the double bond.

Hydrolysis of 1-substituted 7-oxanorborna-2,5-diene-2,3-dicarboxylates occurred regioselectively at the ester group in the 3-position to give monocarboxylic acids from which diesters containing two different alkoxy groups and amido esters were selectively

IrCl3·3H2O or FeCl3-catalyzed convenient synthesis of 3-hydroxyphthalates has been achieved by a Diels-Alder reaction of furans with dimethyl acetylenedicarboxylate, followed by ring-opening aromatization reaction of the D

A microwave-assisted tandem [3+2] cycloaddition/retro-Diels-Alder reaction of azomethine ylides derived from imines of α-amino esters to dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate derivatives is described. The procedure delivers, in a s

Thin Pd films have been deposited on the inside of capillary-sized tubes through which compounds undergoing Diels-Alder reactions have been flowed while being heated with microwave irradiation; dramatic rate accelerations are observed in the presence of the film, which has been shown to play both a heating and catalytic role. The Royal Society of Chemistry.

The present invention relates to a process for the preparation of 1,4,5- trisubstituted triazoles and 3,4,5-trisubstituted triazoles according to Formulas (Ia) and 5 (Ib), and mesomers and tautomers thereof, wherein a compound according to Formula (II) or Formula (III): is reacted with a compound according to Formula (IV). The process is very useful for the selective and site-specific addition of azide compounds to optionally activated alkynes to form 1,4,5-trisubstuted triazoles and mesomers and tautomers thereof and the application of this process to the covalent functionalisation of biomolecules.

Diels-Alder reactions of the heteroaromatic diene furan proceed with enhanced isolated yields and reversal of endolexo selectivity (2:1 endo vs exo) in the ionic liquids [bmim]BF4 and [bmim]PF6 compared to conventional methods. The p

Studies on the different congeners of the softball were undertaken to explore structural variants for enantioselective encapsulation. Two different spacer elements in the monomeric subunit render the dimeric softball chiral although the monomer itself is achiral. The dimers represent capsules with dissymmetric cavities with volumes ranging from 190 to 390 A3. The cavities are distorted spheres, and asymmetric guests, such as naturally occurring terpenes, generally prefer one enantiomer of the capsule to its mirror image. The selectivities are moderate (up to 4:1). The complexation studies show that the host capsules are flexible enough to arrange themselves comfortably around a guest but still maintain enough rigidity to be influenced by the occupancy of a chiral guest. The enantiomeric capsules can interconvert (racemize) by dissociation and recombination of their subunits.

The reaction of furan with α,β-unsaturated carbonyl dienophiles catalyzed by K10 montmorillonite in the absence of organic solvents produces the corresponding Diels-Alder adducts and, in the case of methyl vinyl ketone, Michael-type products, under much milder conditions than the conventional protocols. The results are consistent with acid catalysis on the clay surface. Acrylates gave lower yields and/or decomposition products. The reaction can be extended to alkynic substrates such as DMAD to afford cycloadducts in good yields.

Bicyclic meso diester 7 was found to undergo enantioselective hydrolysis with PLE (pig liver esterase) generating the chiral monoester 8 in excellent yield with high enantiomeric excess.The chiral monoester 8 was successfully utilized in the improved synthesis of 1R-cis-THF derivative (1), a strong agonist of PAF which we previously developed. Key Words: pig liver esterase; enantioselective hydrolysis; tetrahydrofuran; chiral synthon; platelet activating factor

13C and 1H NMR spectral assignments have been obtained for 2,3-dicarboxymethyl-7-oxabicyclohepta-2,5-diene and 19 of its derivatives.The use of a combination of one-dimensional NMR techniques allowed the unambiguous assignments of all 13C resonances of the bicyclic framework.key words: 1H NMR, 13C NMR, XHCORR, INADEQUATE, oxanorbornadiene derivatives

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Pyrolysis of the furan adducts 3 in the gas phase at low pressure (10-4 mm) formed a mixture of furan and the bicyclic enone 2a with a bridgehead double bond that could be collected in a cold trap.NMR, IR, and UV spectra of this mixture were obtained.Although the enone 2a reacted rapidly with methanol and more slowly with furan, efforts to find products from the reaction of the enone 2a with either ground-state oxygen or one of several unsaturated compounds 9,11,12, or 13 were unsuccessful.Instead, at temperatures above -40 deg C the enone 2a reacted with itself to form a mixture of the three dimers 4a, 4b, and 4c.

A computer-assisted strategy for selecting suitable Lewis acid catalysts in organic synthesis is described.The strategy is based on principal components (PC) analysis of measured Lewis acid properties.A two-component model accounts for 65percent of the variation in a set of 20 descriptors for 116 different Lewis acids.PC-eigenvector projections of the data allow for a systematic search of test candidates in screening experiments.The strategy is demonstrated by experimental studies on 3 Lewis acid-catalyzed reactions: alkylation of silyl enol ether, Diels-Alder reaction, and Friedel-Crafts acylation.

Evidence is adduced from the character of the alkenes which cycloadd to N-sulphinylanilines and from a kinetic investigation of the reactions of N-sulphinylanilines with 1,4-epoxy-1,4-dihydronaphthalene, examining the effects upon reaction rate of solvent polarity, temperature, and substitution in the N-sulphinylanilines, that the cycloadditions are pericyclic reactions of Diels-Alder type with inverse electron demand.A degree of charge separation in the transition state is indicated but this is small and confined essentially to the sulphinylaniline moiety.

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Starting from "cis-benzene triimine" (3) the N,N'-disubstituted derivatives 8b-f are synthesized in 90-40percent yield.Nitrosation to the N-nitroso compounds 10b-f, spectroscopically identified below -30 deg C, and N2O-elimination lead to the c