Structure-activity relationship study of alkynyl ether insecticide synergists and the development of MB-599 (verbutin)

Structure-activity relationships of aryl alkynyl synergists of the general formula of Ar-Q-R, where Q represents a bridging structure, were studied using a standardised testing system and Relative Potency values. Ethers, esters, oxime ethers, amides and amines were prepared and evaluated. The length of the R-alkynyl chain, the role of the bridge and the substitution of the aromatic ring were examined systematically. The most potent compounds possessed an aromatic ring connected via a bridge of three atoms to an alkynyl chain, forming together a linear side-chain of six atoms. Several highly potent compounds were synthesised of which one (MB-599; proposed common name verbutin) was selected for development as a selective insecticide synergist in crop protection. Its high potential at practical insecticide:synergist ratios makes possible the reduction of the total amount of insect-control chemicals applied, and its use as an additive to produce new formulations of existing insecticides makes it highly advantageous in resistance management, giving a new tool to sustain the effectiveness of a wide range of insecticides. A product containing a (1+1) mixture of verbutin and beta-cypermethrin was launched in Hungary in 2002.

Regio- and enantioselective iridium-catalyzed intermolecular allylic etherification of achiral allylic carbonates with phenoxides

An enantioselective and regioselective iridium-catalyzed allylic etherification is described. The reaction of sodium and lithium aryloxides with achiral (E)-cinnamyl and terminal aliphatic allylic electrophiles in the presence of 2 mol % of an iridium-phosphoramidite complex provides chiral allylic aryl ethers in high yields and excellent levels of regio- and enantioselectivity. Lithium aryloxides containing a single substituent at an ortho, meta, or para position as well as sterically hindered phenoxides were tolerated. Reactions in THF displayed the most suitable balance of rate, regio-, and enantioselectivity. High ee's were also observed for the products from the reaction of alkyl (E)-allylic carbonates.

Synthesis and cytotoxicity of dihydroartemisinin ethers containing cyanoarylmethyl group

A new type of ether of dihydroartemisinin containing cyano and aryl groups was prepared and tested for cytotoxicity to A549, P388, L1210 and HT29 cells using the MTT assay. 12k and 12l were the most cytotoxic compounds. 13 lacking the peroxy group showed a 1000-fold less potency than 12l. Similarly, the inactive compound 14 indicated that the position of cyano groups was also important. Flow cytometry data showed that the compounds caused an accumulation of P388 cells in the G(1)-phase of the cell cycle.

Synthesis of vanillin ethers from 4-(bromomethyl) coumarins as anti-inflammatory agents

4-(Bromomethyl) coumarins 1 have been reacted with vanillins, 2 and 2A to obtain the corresponding ethers 3 and 5. Ethers 3 have been reacted with ethyl cyanoacetate to obtain the unsaturated esters 4. Ethers 5 have been converted to the corresponding 4-(2'-benzo[b] furanyl) coumarins 6 by an intramolecular aldol condensation. Eight compounds have been screened for their anti-inflammatory activity. Out of these the 5,6-benzo-4-2'-benzo[b]furanyl) coumarin (6c) and the aryloxymethyl coumarin (4) with p-formyl group were found to be most active.

Synthesis of 1,2-diheteroatom-substituted alkenes via rhodium-catalyzed intramolecular hydrogen transfer

While 1,2-diheteroatom-substituted alkenes represent useful synthetic building blocks, there are no simple, general procedures available for preparation of such compounds. We describe here a simple catalytic procedure based on rhodium C-H bond activation for the synthesis of diheteroatom alkenes of the type R(3)SiOCH=CHG (G = -OR, -NRR').

New series of N-substituted phenyl ketone oxime ethers: synthesis and bovine beta3-adrenergic agonistic activities

A series of ten novel phenyl ketone oxime ethers substituted on the terminal nitrogen by either 1,3 benzodioxole, alkyl, aralkyl or aryl moiety were synthesized and tested for their activity at bovine beta3-adrenoceptors. The best compound, which was the benzodioxole dicarboxylate derivative, showed potent beta3-adrenergic agonistic activities in Chinese hamster ovary cells expressing the bovine beta3-adrenoceptors with Kact and Ki values better than compound CL 316,243 used as reference (14 +/- 6 nM and 203 +/- 71 nM, respectively). In this series three compounds showed an antagonistic activity. Structure-activity relationships in these ketone oxime ethers are discussed.

Synthesis, antifungal activity, and molecular modeling studies of new inverted oxime ethers of oxiconazole

Some new oxime ethers of types 7 and 8, in which the methyleneaminoxy group, C=N-O, of oxiconazole 6 is in an inverted atomic sequence, were synthesized and tested for their antifungal activities. Among them, the type 7 compounds, such as the N-ethoxy-morpholino-substituted derivatives 7l-o (Table 1), showed good antifungal properties against the Candida strains tested, with minimum inhibitory concentration (MIC) values similar to those of the reference drug 6. A remarkable result was obtained with these types of azoles, which had shown a cidal character against Candida albicans, while the reference drug oxiconazole was only fungistatic in the same tests. This fact may be seen from a comparison of the MIC values with those of the minimum fungicidal concentration (MFC) values for most of the type 7 compounds assayed that have shown differences between the MIC and the MFC, which are lower than three double diluitions. A simple molecular modeling of the P450 14-alpha-sterol demethylase from C. albicans (Candida P450DM) was built in order to understand how the structural differences between type 7 compounds and oxiconazole 6 can induce different antifungal profiles. The results of this work seem to confirm that it is possible to reverse the atomic sequence of the methyleneaminoxy group, C=N-O, of 6, obtaining new imidazoles possessing good antifungal properties.

Spirocyclic NK(1) antagonists II: [4.5]-spiroethers

A series of novel spiroether-based neurokinin-1 (NK(1)) antagonists is described. The effect of modifications to the spiroether ring and aromatic substituents are discussed, leading to the identification of compounds with high affinity and excellent CNS penetration.

Electron transfer initiated heterogenerative cascade cyclizations: polyether synthesis under nonacidic conditions

[reaction: see text] Single-electron oxidation has been employed to initiate heterogenerative cascade cyclization reactions that form polyether compounds under essentially neutral conditions. The reactions proceed through mesolytic benzylic carbon-carbon bond cleavages of homobenzylic ether-derived radical cations followed by intramolecular epoxonium ion formation, leading to further cyclizations. Both oligotetrahydrofuran and tetrahydropyran structures can be prepared by altering substrate topography.

Regio- and enantiospecific rhodium-catalyzed allylic etherification reactions using copper(I) alkoxides: influence of the copper halide salt on selectivity

The transition metal-catalyzed allylic etherification represents a fundamentally important cross-coupling reaction for the construction of allylic ethers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic etherification of acyclic unsymmetrical allylic alcohol derivatives using copper(I) alkoxides derived from primary, secondary and tertiary alcohols. This study demonstrates that the choice of copper(I) halide salt is crucial for obtaining excellent regio- and enantiospecificity, providing another example of the effect of halide ions in asymmetric transition metal-catalyzed reactions. Finally, the ability to alter the reactivity of the alkali metal alkoxides in this manner may provide a useful method for related metal-catalyzed cross-coupling reactions involving heteroatoms.

Asymmetric total synthesis of highly symmetric squalene-derived cytotoxic polyethers

The efficient total synthesis of the cytotoxic meso polyether teurilene (1), rarely occurring in nature, was achieved through the effective combination of the concept of two-directional synthesis and rhenium(VII) chemistry. In the key rhenium(VII)-promoted syn oxidative cyclization reaction of the two-directional substrate 16, trans-syn diastereoselectivity (steric control) has been observed in contrast to our early observation of cis-syn diastereoselectivities (chelation control) for bishomoallylic tertiary alcohols 24-27 possessing the neighboring tetrahydrofuran (THF) ring. This synthesis in only 10 steps from commercially available methyl tiglate is significantly shorter than the previous one requiring 25 steps. The total syntheses of four possible C(s) symmetric (3 and 47-49) and one C2 symmetric (4) compounds for biogenetically squalene-derived pentaTHF polyether, glabrescol, was also achieved in relatively few steps by taking advantage of its intrinsic symmetry and one- and two-directional modes of double THF ring formations with vanadium catalyst, tert-butyl hydroperoxide (TBHP), and trifluoroacetic acid (TFA). Thus, the meso structure 3 originally proposed by Jacobs et al. has been revised to the optically pure C2 symmetric structure 4 through its enantioselective total synthesis.

Rearrangement of a mesylate tropane intermediate in nucleophilic substitution reactions. Synthesis of aza-bicyclo[3.2.1]octane and aza-bicyclo[3.2.2]nonane ethers, imides, and amines

Nucleophilic substitution of 2beta-mesyloxymethyl-N-methyl-3beta-p-tolyl-tropane intermediate with alkoxides, metal imides, or amines was found to lead not only to the expected bicyclo[3.2.1]octane (tropane) ether, imide, and amine derivatives but also to unexpected bicyclo[3.2.2]nonane derivatives. When alkoxides were used as nucleophile, only the rearranged bicyclo[3.2.2]nonane structure was obtained, whereas the use of amines or imides as nucleophile afforded a mixture of the two structures. The bicyclo[3.2.2]nonane structure was assigned by NMR analysis.

Application of ruthenium-induced macrocyclization for the construction of macrocyclic depsipeptides

The synthesis of a biaryl ether containing macrocyclic depsipeptide 1 was achieved in 6% overall yield. The desired macrocycle was constructed by cyclization of a phenol into eta(6)-ruthenium complex. The ruthenium metal was subsequently photolytically deprotected to obtain the macrocycle 1.

Ullmann diaryl ether synthesis: rate acceleration by 2,2,6,6-tetramethylheptane-3,5-dione

[reaction: see text]. In the copper salt catalyzed ether formation from aryl bromides or iodides and phenols, 2,2,6,6-tetramethylheptane-3,5-dione (TMHD) was found to greatly accelerate the ordinarily difficult reaction, making it occur under more moderate temperatures and reaction times. A series of aryl halides and phenols were shown to form ethers in NMP as the solvent, cesium carbonate as the base, and CuCl and TMHD as the catalysts. The reaction was shown to tolerate electron-rich aryl bromides and electron-neutral phenols.

Radical scavenging activity and cytotoxicity of phenethyl ether and cinnamic amide derivatives

Novel phenethyl ether derivatives (PhE) and cinnamic amide derivatives (CA), which have two mono- or polyphenol rings connected either by an ether (PhE) or amide bond (CA), were synthesized. We investigated their ability to scavenge the O2- and DPPH radicals in vitro, using ESR spectroscopy, in relation to their cytotoxic activity against a human oral squamous cell carcinoma (HSC-2) cell line. The radical scavenging activity was considerably influenced by the position of the hydroxyl groups in the benzene rings. Based on their radical scavenging activity and cytotoxicity, these compounds were classified into two groups: active compounds (such as catechol and hydroquinone) and inactive compounds (such as resorcin and phenol). These results suggest a close relationship between the cytotoxic activity and radical scavenging activity derived from ortho-para preference in dihydroxybenzene. PhE and CA might show potential activity in free radical mediated diseases.

Asymmetric catalysis of hetero-ene reactions with tridentate Schiff base chromium(III) complexes

Tridentate Schiff base chromium(III) complex 1 catalyzes the asymmetric hetero-ene reaction between aryl aldehydes and either 2-methoxypropene or 2-trimethylsilyloxypropene to provide a series of beta-hydroxyenol ether products in high yields and enantioselectivities. X-ray crystallographic analysis of a closely related chromium complex reveals a bridged, dimeric structure bearing aquo-bound six-coordinate Cr(III) centers. A mechanism is proposed wherein water dissociation is effected by means of a chemical desiccant (BaO or silyl enol ether), thereby revealing the site for aldehyde complexation.

Chemical synthesis and calcium release activity of N(1)-ether strand substituted cADPR mimic

8-Chloro cyclic inosine 5'-diphosphate ethoxymethyl ether 3 was synthesized by means of chemical method from protected inosine via phenylthio-type biphosphate substrate. The detection of Ca(2+) release activity shows that 3 is a potent agonist of cADPR and has activity in intact Hela cells.

Stereoselective additions of chiral (E)-crotylsilanes to thionium ions: asymmetric synthesis of homoallylic thioethers

Stereochemically well-defined homoallylic thioethers 3 are synthesized via Lewis acid promoted condensation reaction between chiral organosilane reagents 2 and in situ generated thionium ions. The stereochemical course of the reaction is consistent with earlier reports concerning crotylsilations of oxonium ions.

An improved synthesis of a trifurcated newkome-type monomer and orthogonally protected two-generation dendrons

The one-step synthesis of amino-polyether tri-tert-butyl ester monomer 2, by condensation of TRIS with tert-butyl acrylate, is reported. The nitrogen of the monomer can be protected with a Cbz group; subsequent removal of the tert-butyl esters with formic acid affords a triacid that is coupled to three monomers to afford an orthogonally protected two-generation, trifurcated polyether-polyamide dendron. The Cbz protecting group may be removed from the second-generation dendron without disturbing the tert-butyl esters of the periphery.

4-[18F]fluoroarylalkylethers via an improved synthesis of n.c.a. 4-[18F]fluorophenol

This paper describes the improved synthesis of n.c.a. 4- 18F]fluorophenol for the preparation of 18F-labeled alkylarylethers. Nucleophilic fluorination of substituted benzophenone derivatives yielded n.c.a. 4- 18F]fluoro-4'-substituted benzophenones with 80- 90% RCY, which were converted to benzoic acid phenylesters by treatment with peracetic acid. Strong electron-withdrawing substituents like nitro, cyano and trifluoromethyl favor a fluorophenyl-to-oxygen migration resulting in the formation of corresponding benzoic acid fluorophenylesters. N.c.a. 18F]fluorophenol is almost quantitatively formed after hydrolysis and can easily be converted with alkylhalides into n.c.a. 18F]fluoroarylalkylethers.

Regioselective functionalization of starch: synthesis and 1H NMR characterization of 6-O-silyl ethers

A high regioselective 6-O silylation of starch by using thexyldimethylchlorosilane (TDSCl, chlorodimethyl-(2,3-dimethylbut-2-yl)silane) as bulky silylating agent in the reaction system N-methylpyrrolidone (NMP)/ammonia was carried out and investigated. The control of the degree of substitution (DSSi), the control of the regioselectivity, and the control of the reaction pathway are described in detail. After peracetylation of the silyl ethers of starch, the distribution of the silyl and acetyl substituents was characterized not only in the anhydroglucose repeating units (AGU) but also in the nonreducing end groups (NEG) by means of multidimensional 1H NMR techniques. In both cases, the silyl substituents were detected exclusively in the 6-O position, and the acetyl groups in the 2-O and 3-O positions of the AGU and in the 2-O, 3-O, and 4-O positions of the NEG, respectively. The described 6-O-thexyldimethylsilyl (TDS) units are potentially protecting groups of the primary OH position of starches.

A rapid access to biaryl ether containing macrocycles by pairwise use of Ugi 4CR and intramolecular S(N)Ar-based cycloetherification

[reaction: see text] From readily accessible starting materials, macrocycles with an endo aryl-aryl ether bond are synthesized in only two operations by combination of the Ugi four-component reaction and an intramolecular S(N)Ar reaction. The nitro group serves as an activator for the macrocyclization and provides a handle for the introduction of functional group diversity. A Ugi reaction promoted by ammonium chloride in aprotic solvent is documented for the first time.

Palladium-catalyzed intramolecular C-O bond formation

A number of oxygen heterocycles were synthesized using the palladium-catalyzed intramolecular etherification of aryl halides by employing di-tert-butylphosphinobiaryl ligands. The reaction proceeds under mild conditions using weak bases such as Cs(2)CO(3) or K(3)PO(4). A variety of functional groups are tolerated in the reaction, and enantioenriched alcohols can be coupled without erosion of optical purity. The mildness of the reaction conditions allows for the use of polyfunctionalized substrates. This method was used as the key step in the synthesis of MKC-242, an antidepressant currently in clinical trials. The synthesis of MKC-242 was achieved in 40% overall yield from commercially available sesamol and acrylonitrile.

A review of the development of a synthetic corneal onlay for refractive correction

A synthetic corneal onlay, or implantable contact lens, could obviate the need for spectacles or conventional contact lenses in patients who seek convenient, reversible correction of refractive error. Several research groups have attempted to develop such a product in the past but much of the data from these studies remains unpublished due to commercial interests. This article reviews relevant papers and patents in the corneal implant field and discusses our efforts to develop a synthetic corneal onlay using a perfluoropolyether-based polymer.

[125/123I] 5-Iodo-3-pyridyl ethers. syntheses and binding to neuronal nicotinic acetylcholine receptors

Three 3-pyridyl ether nicotinic ligands-(S)-5-Iodo-3-[(2-pyrrolidinyl)-methoxy]pyridine (5-iodo-A-85865), (S)-5-Iodo-3-[1-(methyl)-2-pyrrolidinyl-methoxy]pyridine (5-Iodo-A-84543), and (S)-5-iodo-3-[1-methyl-(2-azetidinyl)-methoxy]pyridine (5-iodo-N-Me-A-85380) were labeled with I-125/I-123, and their ability to label high-affinity brain nicotinic acetylcholine receptors (nAChRs) was evaluated. The most promising ligand, [123/125I] 5-iodo-A-85865, showed approximately 65% inhibition of radioactivity uptake in thalamus in mice pretreated with cytisine. Preliminary SPECT imaging studies with [123I] 5-iodo-A-85865 revealed a distribution profile consistent with nAChRs (thalamus > frontal cortex > cerebellum) and a more rapid pharmacokinetic profile relative to azetidinyl 3-pyridyl ether based ligands.

Synthesis and in-vitro/in-vivo evaluation of orally administered entacapone prodrugs

Entacapone is a new inhibitor of catechol-O-methyltransferase (COMT) that is used as an adjunct to L-dopa therapy in the treatment of Parkinson's disease. The bioavailability of orally administered entacapone is, however, relatively low (29-46%). In this study we have prepared more lipophilic acyl and acyloxyacyl esters, an acyloxy alkyl ether and an alkyloxycarbonyl ester of entacapone, and we have evaluated them as potential prodrugs to enhance the oral bioavailability of entacapone. All the derivatives fulfilled prodrug criteria and released entacapone in human serum in-vitro. The oral bioavailability of monopivaloyl (1a) and dipivaloyl (1b) esters of entacapone were investigated further in rats. The lipophilicity of 1b was high (log Papp 4.0 at pH 7.4) but its oral bioavailability was low (F = 0.6%), most probably due to its low aqueous solubility. The monopivaloyl ester of entacapone (1a) had a higher lipophilicity (log Papp 0.80) than entacapone (log Papp 0.18) at pH 7.4 while maintaining an aqueous solubility equal to entacapone. However, oral bioavailability was not increased when compared with the parent drug entacapone (F = 7.0% and 10.4%, respectively).

Synthesis of LJP 993, a multivalent conjugate of the N-terminal domain of beta2GPI and suppression of an anti-beta2GPI immune response

LJP 993, a tetravalent conjugate of the amino-terminal domain (domain 1) of beta2GPI, was synthesized, and studies were carried out to explore the ability of LJP 993 to bind anti-beta2GPI antibodies and to function as a B cell toleragen. Domain 1 was expressed in Pichia pastoris, and the N-terminus was site-specifically modified by a transamination reaction converting the N-terminal glycine to a glyoxyl group. A tetravalent platform was synthesized with linkers that terminate in aminooxy groups. This was accomplished by preparing an ethylene glycol-based heterobifunctional linker that contains both a Boc-protected aminooxy group and a free primary amine. The linker was used to modify a tetravalent platform molecule by reacting the amino groups on the linker with 4-nitrophenyl carbonate esters on the platform to provide a linker-modified platform, and the Boc protecting groups were removed to provide a tetravalent aminooxy platform. Glyoxylated domain 1 was attached to the platform to provide LJP 993 by formation of oxime bonds. The protein domains of LJP 993 retain activity as evidenced by the ability of LJP 993 to bind to anti-beta2GPI antibodies. Dissociation constants (Kd) for domain 1 and LJP 993 bound to immobilized affinity-purified anti-beta2GPI antibodies from autoimmune thrombosis patients were determined using surface plasmon resonance. An immunized mouse model was developed to test the ability of LJP 993 to act as a toleragen. A thiol containing domain 1 analogue was expressed in insect cells using the baculovirus expression system, and it was used to prepare an immunogenic conjugate of domain 1 and maleimide-derivatized keyhole limpet hemocyanin (KLH). Mice were immunized with the KLH conjugate, and spleen cells were harvested from the immunized mice. The cells were incubated with various concentrations of LJP 993 and transferred to mice whose immune systems had been compromised by irradiation. The hosts were then boosted with the KLH-domain 1 conjugate, and after 7 days their antibody levels were measured. Host mice receiving cells that were treated with LJP 993 produced significantly lower amounts of anti-domain 1 antibodies than controls which received untreated cells, indicative of B cell tolerance.

Structure-based design of caspase-1 inhibitor containing a diphenyl ether sulfonamide

A series of compounds was designed and prepared as inhibitors of interleukin-1beta converting enzyme (ICE), also known as caspase-1. These inhibitors, which employ a diphenyl ether sulfonamide, were designed to improve potency by forming favorable interactions between the diphenyl ether rings and the prime side hydrophobic region. An X-ray crystal structure of a representative member of the diphenyl ether sulfonamide series bound to the active site of caspase-1 was obtained.

One-pot synthesis of cinnamylamines with various protecting groups from cinnamyl ethers

The reaction of various alkyl cinnamyl ethers with CSI afforded the corresponding cinnamylamines with various protecting groups, such as -NHMoc, -NHiPoc, -NHCbz, -NHPnz, -NHTroc and -NHAloc. In the case of cinnamyl t-butyl ether and cinnamyl p-methoxybenzyl ether, the corresponding cinnamyl carbamates were formed via a different reaction pathway from the above.

Regiospecific analysis of neutral ether lipids by liquid chromatography/electrospray ionization/single quadrupole mass spectrometry: validation with synthetic compounds

A reversed-phase high-performance liquid chromatography (HPLC) method with on-line electrospray ionization/collision-induced dissociation/mass spectrometry (ESI/CID/MS) is presented for the regiospecific analysis of synthetic reference compounds of neutral ether lipids. The reference compounds were characterized by chromatographic retention times, full mass spectra, and fragmentation patterns as an aid to clarify the regiospecificity of ether lipids from natural sources. The results clearly show that single quadrupole mass spectroscopic analysis may elucidate the regiospecific structure of neutral ether lipids. Ether lipid reference compounds were characterized by five to six major ions in the positive ion mode. The 1-O-alkyl-sn-glycerols were analyzed as the diacetoyl derivative, and showed the [M - acetoyl](+) ion as an important diagnostic ion. The diagnostic ions of directly analyzed 1-O-alkyl-2-acyl-sn-glycerols and 1-O-alkyl-3-acyl-sn-glycerols were the [M - alkyl](+), [M + H - H(2)O](+) and [M + H](+) ions. Regiospecific characterization of the fatty acid position was evident from the relative ion intensities, as the sn-2 species had relatively high [M + H](+) ion intensities compared with [M + H - H(2)O](+), whereas the reverse situation characterized the sn-3 species. Furthermore, corresponding sn-2 and sn-3 species were separated by the chromatographic system. However, loss of water was promoted as fatty acid unsaturation was raised, which may complicate interpretation of the mass spectra. The diagnostic ions of directly analyzed 1-O-alkyl-2,3-diacyl-sn-glycerols were the [M - alkyl](+), [M - sn-2-acyl](+) and [M - sn-3-acyl](+) ions. Regiospecific characterization of the fatty acid identity and position was evident from the relative ion intensities, as fragmentation of the sn-2 fatty acids was preferred to the sn-3 fatty acids; however, loss of fatty acids was also promoted by higher degrees of unsaturation. Therefore, both structural and positional effects of the fatty acids affect the spectra of the neutral ether lipids. Fragmentation patterns and optimal capillary exit voltages are suggested for each neutral ether lipid class. The present study demonstrates that reversed-phase HPLC and positive ion ESI/CID/MS provide direct and unambiguous information about the configuration and identity of molecular species in neutral 1-O-alkyl-sn-glycerol classes.

Optically active BINOL core-based phenyleneethynylene dendrimers for the enantioselective fluorescent recognition of amino alcohols

A dramatic enhancement in fluorescence intensity from 1,1'-bi-2-naphthol (BINOL) to dendritic phenyleneethynylenes containing the BINOL core was observed. The strong fluorescence of the dendrimers allows a very small amount of the chiral materials to be used for sensing. The light harvesting antennas of the dendrimer funnel energy to the center BINOL unit, whose hydroxyl groups upon interaction with a quencher molecule lead to fluorescence quenching. This mechanism makes the dendrimers have much more sensitive fluorescence responses than corresponding small molecule sensors. The fluorescence of these dendrimers can be enantioselectively quenched by chiral amino alcohols. It is observed that the fluorescence lifetime of the generation two dendrimer does not change in the presence of various concentrations of 2-amino-3-phenyl-1-propanol. This demonstrates that the fluorescence quenching is entirely due to static quenching. Thus, formation of nonfluorescent ground-state hydrogen-bond complexes between the dendrimers and amino alcohols is proposed to account for the fluorescent quenching. A linear relationship has been established between the Stern-Völmer constant of the generation two dendrimer and the enantiomeric composition of 2-amino-3-phenyl-1-propanol. Such enantioselective fluorescent sensors may allow a rapid determination of the enantiomeric composition of chiral molecules and are potentially useful in the combinatorial search of asymmetric catalysts and reagents.

Synthesis and liquid membrane transport properties of photolabile molecular clips based on dithiane-spiro-crown ethers

[reaction: see text]. Synthesis of novel dithiane-spiro-crown ethers starting from 5,5-di(hydroxymethyl)-1,3-dithiane is developed. These compounds can be used as building blocks to assemble photolabile bis-crown ethers via addition to dicarbonyl-containing tethers, e.g., isophthalic aldehyde. It is found that unlike their mono-crown precursors such bidentate bis-crowns are capable of efficient liquid membrane transport of, for example, methyl viologen. The transport can be interrupted photochemically, providing a basis for developing smart light-responsive membranes.

[Synthesis and pharmacologic action of chiral fomocaine ((4-[2-methyl-3-(morpholin-4-yl)propyl)benzyl)-phenyl-ether and (4-(1-methyl-3-(morpholin-4-yl)propyl]benzyl)-phenyl-ether). 13. Synthesis of new compounds with local anesthetic action]

The syntheses of two chiral fomocaines namely rac ((4-[2-methyl-3-(morpholin-4-yl)propyl]-benzyl)-phenyl-ether (O/G 3) and rac (4-[1-methyl-3-(morpholin-4-yl)propyl]benzyl)-phenyl-ether) (O/G 5) are reported. These compounds are part of a new research program concerning the relation between chirality and local anaesthetic activity in the group of fomocaines. The yield over five steps is in the range of 9% (O/G 3) up to 19.2% (O/G 5). The racemates were resoluted via the diastereomeric salts formed with (+)- or (-)-camphersulfonic acid. The chromatographic resolution in analytical scale is successful using a Daicel OD-column. The enantiomers are stable. The surface anaesthesia of the racemates as well as of the enantiomeres is weaker in comparison with fomocaine. The rate of tissue irritation is higher. The LD50 (mouse i.v.) is in the range between 290-390 mg/kg, while fomocaine shows a LD50 value of 175 mg/kg.

Synthesis of lipid A type pyran carboxylic acids with ether chains and their biological activities

Synthesis of lipid A type pyran carboxylic acids having ether chains at both the C-3' and C-4 positions and their bioactivities toward human U937 cells are described.

Ergosteroids IV: synthesis and biological activity of steroid glucuronosides, ethers, and alkylcarbonates

The 7-oxo derivative of dehydroepiandrosterone is more active than the parent steroid and is devoid of adverse side effects in rats, monkeys and humans. In anticipation of possible therapeutic use we have sought more active, longer lasting forms of 7-oxo- and 7beta-hydroxydehydroepiandrosterones. The 7-oxo- and 7-hydroxy steroids have been converted to glucuronides, ethers and carbonate esters. The syntheses of these compounds are described and their ability to induce the formation of liver thermogenic enzymes when fed to rats is reported. Some of the new derivatives were found to be somewhat more effective than the equimolar amounts of 7-oxo-DHEA with which they were compared in each experiment.

Synthesis of some 1-(2-naphthyl)-2-(imidazole-1-yl)ethanone oxime and oxime ether derivatives and their anticonvulsant and antimicrobial activities

In this study, oxime and oxime ether derivatives of anticonvulsant nafimidone [1-(2-naphthyl)-2-(imidozole-1-yl)ethanone] were prepared as potential anticonvulsant compounds. Nafimidone oxime was synthesized by the reaction of nafimidone and hydroxylamine hydrochloride. O-Alkylation of the oxime by various alkyl halides gave the oxime ether derivatives. Anticonvulsant activity of the compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) tests in mice and rats according to procedures of the Antiepileptic Drug Development (ADD) program of the National Institutes of Health (NIH). In addition to anticonvulsant evaluation, compounds were also screened for possible antibacterial and antifungal activities because of the structural resemblance to the azole antifungals, especially to oxiconazole. All compounds were evaluated against three human pathogenic fungi and four bacteria using the microdilution method. Most of the compounds exhibited both anticonvulsant and antimicrobial activities; the O-alkyl substituted compounds (2, 3, 4 and 5) were found to be more active than the O-arylalkyl substituted compounds in both screening paradigms.

Spectroscopic diagnostics of organic chemistry in the protostellar environment

A combination of astronomical observations, laboratory studies, and theoretical modelling is necessary to determine the organic chemistry of dense molecular clouds. We present spectroscopic evidence for the composition and evolution of organic molecules in protostellar environments. The principal reaction pathways to complex molecule formation by catalysis on dust grains and by reactions in the interstellar gas are described. Protostellar cores, where warming of dust has induced evaporation of icy grain mantles, are excellent sites in which to study the interaction between gas phase and grain-surface chemistries. We investigate the link between organics that are observed as direct products of grain surface reactions and those which are formed by secondary gas phase reactions of evaporated surface products. Theory predicts observable correlations between specific interstellar molecules, and also which new organics are viable for detection. We discuss recent infrared observations obtained with the Infrared Space Observatory, laboratory studies of organic molecules, theories of molecule formation, and summarise recent radioastronomical searches for various complex molecules such as ethers, azaheterocyclic compounds, and amino acids.

Antimitotic and cell growth inhibitory properties of combretastatin A-4-like ethers

A series of diarylamines, diaryl and arylbenzyl ethers based on combretastatin A-4 was prepared and evaluated for anticancer activity. 2-Methoxy-5-(3',4',5'-trimethoxyphenoxymethyl)phenol was the most active (IC50, K562 20 nM) and caused significant G2/M cell cycle arrest.

Semifluorinated symmetrical diethers for intraocular use: synthesis, characterization, and in vitro biocompatibility

Semifluorinated symmetrical diethers were synthesized using the William ether synthesis. These diethers should have similar properties to perfluorocarbons as are chemical inertness and high oxygen solubility, but in contrast a considerably lower density. With their lower density the damaging of the choroidal tissue of the eye observed with perfluorocarbons should be avoided. The synthesized diethers are inert compounds being stable against nucleophiles, oxidiziers and strong bases. Their density is in the range of 1.1-1.2 g/cm3. Besides the physical and chemical tests we conducted several in vitro biocompatibility tests. The tests comprised induction of hemolysis, the generation of C3a complement, the influence on the production of interleukin1beta, the influence on cell proliferation of a Raji and a Hela cell line (3H-Thymidine uptake) and finally the direct cytotoxic effect on these cell lines. All tested symmetrical diethers were positive in one or more tests and can be expected to be incompatible in vivo. Especially the "short" semifluorinated diethers [(CF3CH2O)2(CH2)3-6] showed a nearly total inhibition of cell proliferation or interleukin1beta release. Further variation of the compounds will be necessary to generate better biocompatible derivates.

A novel synthetic methods for alpha-amino acids from allyl ethers via N-allylcarbamates

Protected alpha-Phenyl glycine 17 and phenylalanine 18 and 19 have been synthesized through an efficient three-step sequence from the corresponding allyl ethers 5, 7, and 10. The key intermediate in this synthesis is the corresponding allylic amines prepared by reaction of allyl ethers with chlorosulfonyl isocyanate.

A new thioether-ligated iron porphyrin as a model of a protonated form of P450 active site

Thioether-ligated iron porphyrin (complex 1) was synthesized as a model of the protonated form of P450 to explore the possible involvement of the protonated form in the catalytic cycle, and ether-ligated iron porphyrin (complex 2) was also synthesized for comparison. The thioether and ether ligands enhanced heterolytic O-O bond cleavage of peroxy acid-iron porphyrin complex even in highly hydrophobic media without the assistance of acid or base, using mCPPAA as an oxidant. Competitive oxidation of cyclooctane/cyclooctene catalyzed by iron porphyrins showed that complexes 1 and 2 are less effective than heme thiolate (P450 and a synthetic heme thiolate (SR complex)) in oxidizing alkane. The possibility that thiol-ligated heme, which is a protonated form of heme thiolate, is not involved in the active intermediate structure of P450 is indicated by this result. This is the first report concerning the oxidizing ability of a thioether-ligated iron porphyrin.

Rhodium-catalyzed formylation of organomercurials: application to efficient polyol synthesis

The rhodium-catalyzed formylation of organomercurials-a new transformation of organomercurials-is reported. The addition of 0.50 equiv of 1,4-diazabicyclo[2.2.2]octane (DABCO) was found to promote the reaction, and it is postulated that the DABCO acts as a ligand for mercury. Several examples are presented to document the scope of the reaction. This reaction was developed in the context of a larger program focused on the development of efficient strategies for the synthesis of polyol-derived natural products, and an efficient (8 steps) synthesis of Tolypothrix pentaether that employs this methodology is reported.

A synthetic transmembrane polyether model active in lipid bilayers

A model polyether-based ion channel-like compound was rationally designed and synthesized. Macromolecules 1c-f were incorporated into phospholipid vesicles and shown to facilitate the transmembrane sodium transport.

Preparation of polyetherol-appended sulfur porphyrazines and investigations of peripheral metal ion binding in polar solvents

We describe the complete synthesis and characterization of a new family of peripherally functionalized porphyrazines (pz's) with four, three, or two (in a trans conformation) bis[thioethoxy(ethoxy)ethanol] moieties appended at the pyrroles. These "polyetherol" groups serve as weak exocyclic binding sites for a number of metal ions and also provide solubility of the pz's in low molecular-weight alcohols and water. Electronic spectra of the modified porphyrazines exhibit distinct changes in the visible region (both absorbance and fluorescence) in response to treatment with Ag+, Pb2+, Cd2+, Cs+, and Ni2+ in solution. Such properties make these compounds intriguing candidates for incorporation into the transducer layers in optically based chemical sensors.

First synthesis of a alpha-trifluoromethyl allenol ether via the Julia-Lythgoe process

Alpha-trifluoromethyl allenol ethers 9a-e were prepared in moderate to good yields by the Julia-Lythgoe process using beta-ethoxy-beta-trifluoromethyl vinylic sulfone 3. Several reactions of 9c were examined to give alpha,beta-unsaturated trifluoromethyl ketone derivatives 11 and 12.